1
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Siachouli P, Karadima KS, Mavrantzas VG, Pandis SN. The effect of functional groups on the glass transition temperature of atmospheric organic compounds: a molecular dynamics study. SOFT MATTER 2024; 20:4783-4794. [PMID: 38847330 DOI: 10.1039/d4sm00405a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Organic compounds constitute a substantial part of atmospheric particulate matter not only in terms of mass concentration but also in terms of distinct functional groups. The glass transition temperature provides an indirect way to investigate the phase state of the organic compounds, playing a crucial role in understanding their behavior and influence on aerosol processes. Molecular dynamics (MD) simulations were implemented here to predict the glass transition temperature (Tg) of atmospherically relevant organic compounds as well as the influence of their functional groups and length of their carbon chain. The cooling step used in the simulations was chosen to be neither too low (to supress crystallization) nor too high (to avoid Tg overprediction). According to the MD simulations, the predicted Tg is sensitive to the functional groups as follows: carboxylic acid (-COOH) > hydroxyl (-OH) and (-COOH) > carbonyls (-CO). Increasing the number of carbon atoms leads to higher Tg for the linearly structured compounds. Linear compounds with lower molecular weight were found to exhibit a lower Tg. No clear correlation between O : C and Tg was observed. The architecture of the carbon chain (linear, or branched, or ring) was also found to impact the glass transition temperature. Compounds containing a non-aromatic carbon ring are characterized by a higher Tg compared to linear and branched ones with the same number of carbon atoms.
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Affiliation(s)
- Panagiota Siachouli
- Department of Chemical Engineering, University of Patras, Patras, GR 26504, Greece.
- Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Patras, GR 26504, Greece
| | - Katerina S Karadima
- Department of Chemical Engineering, University of Patras, Patras, GR 26504, Greece.
- Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Patras, GR 26504, Greece
| | - Vlasis G Mavrantzas
- Department of Chemical Engineering, University of Patras, Patras, GR 26504, Greece.
- Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Patras, GR 26504, Greece
- Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, CH-8092 Zürich, Switzerland
| | - Spyros N Pandis
- Department of Chemical Engineering, University of Patras, Patras, GR 26504, Greece.
- Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Patras, GR 26504, Greece
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2
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Pallaka MR, Simon SL. The glass transition and enthalpy recovery of polystyrene nanorods using Flash differential scanning calorimetry. J Chem Phys 2024; 160:124904. [PMID: 38533885 DOI: 10.1063/5.0190076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Accepted: 01/31/2024] [Indexed: 03/28/2024] Open
Abstract
The glass transition (Tg) behavior and enthalpy recovery of polystyrene nanorods within an anodic aluminum oxide (AAO) template (supported nanorods) and after removal from AAO (unsupported nanorods) is studied using Flash differential scanning calorimetry. Tg is found to be depressed relative to the bulk by 20 ± 2 K for 20 nm-diameter unsupported polystyrene (PS) nanorods at the slowest cooling rate and by 9 ± 1 K for 55 nm-diameter rods. On the other hand, bulk-like behavior is observed in the case of unsupported 350 nm-diameter nanorods and for all supported rods in AAO. The size-dependent Tg behavior of the PS unsupported nanorods compares well with results for ultrathin films when scaled using the volume/surface ratio. Enthalpy recovery was also studied for the 20 and 350 nm unsupported nanorods with evolution toward equilibrium found to be linear with logarithmic time. The rate of enthalpy recovery for the 350 nm rods was similar to that for the bulk, whereas the rate of recovery was enhanced for the 20 nm rods for down-jump sizes larger than 17 K. A relaxation map summarizes the behavior of the nanorods relative to the bulk and relative to that for the 20 nm-thick ultrathin film. Interestingly, the fragility of the 20 nm-diameter nanorod and the 20 nm ultrathin film are identical within the error of measurements, and when plotted vs departure from Tg (i.e., T - Tg), the relaxation maps of the two samples are identical in spite of the fact that the Tg is depressed 8 K more in the nanorod sample.
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Affiliation(s)
- Madhusudhan R Pallaka
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409, USA
| | - Sindee L Simon
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
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3
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Cheng S, Kogut D, Zheng J, Patil S, Yang F, Lu W. Dynamics of polylactic acid under ultrafine nanoconfinement: The collective interface effect and the spatial gradient. J Chem Phys 2024; 160:114904. [PMID: 38506298 DOI: 10.1063/5.0189762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/16/2024] [Indexed: 03/21/2024] Open
Abstract
Polymers under nanoconfinement can exhibit large alterations in dynamics from their bulk values due to an interface effect. However, understanding the interface effect remains a challenge, especially in the ultrafine nanoconfinement region. In this work, we prepare new geometries with ultrafine nanoconfinement ∼10nm through controlled distributions of the crystalline phases and the amorphous phases of a model semi-crystalline polymer, i.e., the polylactic acid. The broadband dielectric spectroscopy measurements show that ultrafine nanoconfinement leads to a large elevation in the glass transition temperature and a strong increment in the polymer fragility index. Moreover, new relaxation time profile analyses demonstrate a spatial gradient that can be well described by either a single-exponential decay or a double-exponential decay functional form near the middle of the film with a collective interface effect. However, the dynamics at the 1-2 nm vicinity of the interface exhibit a power-law decay that is different from the single-exponential decay or double-exponential decay functional forms as predicted by theories. Thus, these results call for further investigations of the interface effect on polymer dynamics, especially for interfaces with perturbed chain packing.
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Affiliation(s)
- Shiwang Cheng
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA
| | - David Kogut
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA
| | - Juncheng Zheng
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA
| | - Shalin Patil
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA
| | - Fuming Yang
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan 48824, USA
| | - Weiyi Lu
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, Michigan 48824, USA
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4
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Baeckmann C, Martínez-Esaín J, Suárez del Pino JA, Meng L, Garcia-Masferrer J, Faraudo J, Sort J, Carné-Sánchez A, Maspoch D. Porous and Meltable Metal-Organic Polyhedra for the Generation and Shaping of Porous Mixed-Matrix Composites. J Am Chem Soc 2024; 146:7159-7164. [PMID: 38467030 PMCID: PMC10958503 DOI: 10.1021/jacs.4c00407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/05/2024] [Accepted: 03/06/2024] [Indexed: 03/13/2024]
Abstract
Here, we report the synthesis of BCN-93, a meltable, functionalized, and permanently porous metal-organic polyhedron (MOP) and its subsequent transformation into amorphous or crystalline, shaped, self-standing, transparent porous films via melting and subsequent cooling. The synthesis entails the outer functionalization of a MOP with meltable polymer chains: in our model case, we functionalized a Rh(II)-based cuboctahedral MOP with poly(ethylene glycol). Finally, we demonstrate that once melted, BCN-93 can serve as a porous matrix into which other materials or molecules can be dispersed to form mixed-matrix composites. To illustrate this, we combined BCN-93 with one of various additives (either two MOF crystals, a porous cage, or a linear polymer) to generate a series of mixed-matrix films, each of which exhibited greater CO2 uptake relative to the parent film.
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Affiliation(s)
- Cornelia
von Baeckmann
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and The
Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra, Spain
- Departament
de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Jordi Martínez-Esaín
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and The
Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra, Spain
| | - José A. Suárez del Pino
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and The
Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra, Spain
- Departament
de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Lingxin Meng
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and The
Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra, Spain
- Departament
de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | | | - Jordi Faraudo
- Institut
de Ciència de Materials de Barcelona (ICMAB-CSIC), 08193 Bellaterra, Spain
| | - Jordi Sort
- Departament
de Física, Universitat Autònoma
de Barcelona, 08193 Bellaterra, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Arnau Carné-Sánchez
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and The
Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra, Spain
- Departament
de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Daniel Maspoch
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and The
Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra, Spain
- Departament
de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
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5
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Mizrahi Rodriguez K, Lin S, Wu AX, Storme KR, Joo T, Grosz AF, Roy N, Syar D, Benedetti FM, Smith ZP. Penetrant-induced plasticization in microporous polymer membranes. Chem Soc Rev 2024; 53:2435-2529. [PMID: 38294167 DOI: 10.1039/d3cs00235g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Penetrant-induced plasticization has prevented the industrial deployment of many polymers for membrane-based gas separations. With the advent of microporous polymers, new structural design features and unprecedented property sets are now accessible under controlled laboratory conditions, but property sets can often deteriorate due to plasticization. Therefore, a critical understanding of the origins of plasticization in microporous polymers and the development of strategies to mitigate this effect are needed to advance this area of research. Herein, an integrative discussion is provided on seminal plasticization theory and gas transport models, and these theories and models are compared to an exhaustive database of plasticization characteristics of microporous polymers. Correlations between specific polymer properties and plasticization behavior are presented, including analyses of plasticization pressures from pure-gas permeation tests and mixed-gas permeation tests for pure polymers and composite films. Finally, an evaluation of common and current state-of-the-art strategies to mitigate plasticization is provided along with suggestions for future directions of fundamental and applied research on the topic.
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Affiliation(s)
- Katherine Mizrahi Rodriguez
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sharon Lin
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Albert X Wu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Kayla R Storme
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Taigyu Joo
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Aristotle F Grosz
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Naksha Roy
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Duha Syar
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Francesco M Benedetti
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Zachary P Smith
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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6
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Phan AD, Schweizer KS. Effect of the nature of the solid substrate on spatially heterogeneous activated dynamics in glass forming supported films. J Chem Phys 2024; 160:074902. [PMID: 38364012 DOI: 10.1063/5.0188016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 01/10/2024] [Indexed: 02/18/2024] Open
Abstract
We extend the force-level elastically collective nonlinear Langevin equation theory to treat the spatial gradients of the alpha relaxation time and glass transition temperature, and the corresponding film-averaged quantities, to the geometrically asymmetric case of finite thickness supported films with variable fluid-substrate coupling. The latter typically nonuniversally slows down motion near the solid-liquid interface as modeled via modification of the surface dynamic free energy caging constraints that are spatially transferred into the film and which compete with the accelerated relaxation gradient induced by the vapor interface. Quantitative applications to the foundational hard sphere fluid and a polymer melt are presented. The strength of the effective fluid-substrate coupling has very large consequences for the dynamical gradients and film-averaged quantities in a film thickness and thermodynamic state dependent manner. The interference of the dynamical gradients of opposite nature emanating from the vapor and solid interfaces is determined, including the conditions for the disappearance of a bulk-like region in the film center. The relative importance of surface-induced modification of local caging vs the generic truncation of the long range collective elastic component of the activation barrier is studied. The conditions for the accuracy and failure of a simple superposition approximation for dynamical gradients in thin films are also determined. The emergence of near substrate dead layers, large gradient effects on film-averaged response functions, and a weak non-monotonic evolution of dynamic gradients in thick and cold films are briefly discussed. The connection of our theoretical results to simulations and experiments is briefly discussed, as is the extension to treat more complex glass-forming systems under nanoconfinement.
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Affiliation(s)
- Anh D Phan
- Faculty of Materials Science and Engineering, Phenikaa University, Hanoi 12116, Vietnam
- Phenikaa Institute for Advanced Study, Phenikaa University, Hanoi 12116, Vietnam
| | - Kenneth S Schweizer
- Departments of Materials Science, Chemistry, Chemical and Biomolecular Engineering and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
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7
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Nobori H, Fujimoto D, Yoshioka J, Fukao K, Konishi T, Taguchi K. Phase transitions and dynamics in ionic liquid crystals confined in nanopores. J Chem Phys 2024; 160:044902. [PMID: 38258924 DOI: 10.1063/5.0185093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 01/01/2024] [Indexed: 01/24/2024] Open
Abstract
We investigate the phase-transition behavior of ionic liquid crystals, namely 1-methyl-3-alkylimidazolium tetrafluoroborate, [Cnmim]BF4, confined in cylindrical nanopores using differential scanning calorimetry, x-ray scattering, and dielectric relaxation spectroscopy. Here, n is the number of carbon atoms in the alkyl part of this ionic liquid crystal. For n = 10 and 12, the isotropic liquid phase changes to the smectic phase and then to a metastable phase for the cooling process. During the subsequent heating process, the metastable phase changes to the isotropic phase via crystalline phases. The transition temperatures for this ionic liquid crystal confined in nanopores decrease linearly with the increase in the inverse pore diameter, except for the transitions between the smectic and isotropic phases. In the metastable phase, the relaxation rate of the α-process shows the Vogel-Fulcher-Tammann type of temperature dependence for some temperature ranges. The glass transition temperature evaluated from the dynamics of the α-process decreases with the decrease in the pore diameter and increases with the increase in the carbon number n. The effect of confinement on the chain dynamics can clearly be observed for this ionic liquid crystal. For n = 10, the melting temperature of the crystalline phase is slightly higher than that of the smectic phase for the bulk, while, in the nanopores, the melting temperature of the smectic phase is higher than that of the crystalline phase. This suggests that the smectic phase can be thermodynamically stable, thanks to the confinement effect.
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Affiliation(s)
- Hiroki Nobori
- Department of Physics, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, Japan
| | - Daisuke Fujimoto
- Department of Physics, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, Japan
| | - Jun Yoshioka
- Department of Physics, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, Japan
| | - Koji Fukao
- Department of Physics, Ritsumeikan University, Noji-Higashi 1-1-1, Kusatsu 525-8577, Japan
| | - Takashi Konishi
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Ken Taguchi
- Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8521, Japan
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8
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Thoms E, Li C, Napolitano S. Tracing the slow Arrhenius process deep in the glassy state-quantitative evaluation of the dielectric relaxation of bulk samples and thin polymer films in the temperature domain. J Chem Phys 2024; 160:034901. [PMID: 38226828 DOI: 10.1063/5.0184382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 12/25/2023] [Indexed: 01/17/2024] Open
Abstract
The slow Arrhenius process (SAP) is a dielectric mode connected to thermally activated equilibration mechanisms, allowing for a fast reduction in free energy in liquids and glasses. The SAP, however, is still poorly understood, and so far, this process has mainly been investigated at temperatures above the glass transition. By employing a combination of methods to analyze dielectric measurements under both isochronal and isothermal conditions, we were able to quantitatively reproduce the dielectric response of the SAP of different polymers and to expand the experimental regime over which this process can be observed down to lower temperatures, up to 70 K below the glass transition. Employing thin films of thicknesses varying between 10 and 800 nm, we further verified that the peak shape and activation energy of the SAP of poly(4-bromostyrene) are not sensitive to temperature, nor do they vary upon confinement at the nanoscale level. These observations confirm the preliminary trends reported for other polymers. We find that one single set of parameters-meaning the activation barrier and the pre-exponential factor, respectively, linked to the enthalpic and entropic components of the process-can describe the dynamics of the SAP in both the supercooled liquid and glassy states, in bulk and thin films. These results are discussed in terms of possible molecular origins of the slow Arrhenius process in polymers.
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Affiliation(s)
- Erik Thoms
- Laboratory of Polymer and Soft Matter Dynamics, Experimental Soft Matter and Thermal Physics (EST), Université Libre de Bruxelles (ULB), Brussels 1050, Belgium
| | - Chun Li
- Laboratory of Polymer and Soft Matter Dynamics, Experimental Soft Matter and Thermal Physics (EST), Université Libre de Bruxelles (ULB), Brussels 1050, Belgium
| | - Simone Napolitano
- Laboratory of Polymer and Soft Matter Dynamics, Experimental Soft Matter and Thermal Physics (EST), Université Libre de Bruxelles (ULB), Brussels 1050, Belgium
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9
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Luo J, Wang X, Tong B, Li Z, Rocchi LA, Di Lisio V, Cangialosi D, Zuo B. Length Scale of Molecular Motions Governing Glass Equilibration in Hyperquenched and Slow-Cooled Polystyrene. J Phys Chem Lett 2024; 15:357-363. [PMID: 38175163 DOI: 10.1021/acs.jpclett.3c03263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Polymer glasses attain thermodynamic equilibrium owing to structural relaxation at various length scales. Herein, calorimetry experiments were conducted to trace the macroscopic relaxation of slow-cooled (SC) and hyperquenched (HQ) polystyrene (PS) glasses and based on detailed comparisons with molecular dynamics probed by dye reorientation, we discussed the possible molecular process governing the equilibration of PS glasses near the glass transition temperatures (Tg). Both SC and HQ glasses equilibrate owing to the cooperative segment motion above a characteristic temperature (Tc) slightly lower than the Tg. In contrast, below the Tc, the localized backbone motion with an apparent activation energy of 290 ± 20 kJ/mol, involving approximately six repeating units, assists equilibrium recovery of PS glasses on the experimentally accessible time scales. The results possibly indicate the presence of an alternative mechanism other than the α-cooperative process controlling physical aging of materials in their deep glassy states.
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Affiliation(s)
- Jintian Luo
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Xiang Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Ben Tong
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Zhiqiang Li
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Lorenzo Augusto Rocchi
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, 00185 Rome, Italy
| | - Valerio Di Lisio
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastian, Spain
| | - Daniele Cangialosi
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastian, Spain
- Centro de Física de Materiales, Paseo Manuel de Lardizabal 5, 20018 San Sebastian, Spain
| | - Biao Zuo
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
- Zhejiang Provincial Innovation Center of Advanced Textile Technology, Shaoxing 312000, China
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10
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Cammarata MDM, Contin MD, Negri RM, Factorovich MH. Diffusion Coefficients of Variable-Size Amphiphilic Additives in a Glass-Forming Polyethylene Matrix. J Phys Chem B 2024; 128:312-328. [PMID: 38146058 DOI: 10.1021/acs.jpcb.3c04904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Diffusion of additives in polymers is an important issue in the plastics industry since migratory-type molecules are widely used to tune the properties of polymeric composites. Predicting the diffusional behavior of new additives can minimize the need for repetitive experiments. This work presents molecular dynamics simulations at the microsecond time scale and uses the MARTINI force field to estimate self-diffusion coefficients, D, of six monounsaturated amides and their analogs carboxylic acids in polyethylene matrices (PE, MW = 5600 Da). The results are strongly influenced by the glass-forming properties of the PE matrix, which we characterize by three distinct temperatures. The metastability region (T < 325 K), the glass transition temperature (Tg = 256-260 K), and the end of the transition (T ≅ 200 K). Self-diffusion mechanisms are inferred from the results of the dependence of D on the molecular mass of the additive, observing a Rouse-like behavior at high temperatures and deviations from it within the metastability region of the matrix. Interestingly, D values are nonsensitive to the nature of the considered polar head for additives of similar size. The temperature-dependent behavior of D follows, at fixed additive size, a linear Arrhenius pattern at high temperatures and a super Arrhenius trend at lower temperatures, which is well represented with a power law equation as predicted by the Mode Coupling Theory (MCT). We offer a conceptual explanation for the observed super-Arrhenius behavior. This explanation draws on Truhlar and Kohen's interpretation of the available energies at both the initial and the transition states along the diffusion pathway. The matrix's mobility significantly affects solute self-diffusion, yielding equal activation enthalpies for the Arrhenius region or the same power law parameters for the super-Arrhenius regime. Finally, we establish a one-to-one time-equivalence of the self-diffusion processes between CG and all-atom systems for the largest additives and the PE matrix in the high-temperature regime.
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Affiliation(s)
- María Del Mar Cammarata
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina
| | - Mario D Contin
- Departamento de Ciencias Química, Catedra de Química Analítica. Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 954, Buenos Aires C1113AAD, Argentina
| | - R Martín Negri
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina
| | - Matias H Factorovich
- Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina
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11
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Caporaletti F, Napolitano S. The slow Arrhenius process in small organic molecules. Phys Chem Chem Phys 2024; 26:745-748. [PMID: 38053485 DOI: 10.1039/d3cp05044k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Equilibration, the complex set of molecular rearrangements leading to more stable states, is usually dominated by density fluctuations, occurring through the structural (α-)relaxation, whose timescale quickly increases upon cooling. Growing evidence shows, however, that equilibration can be reached also through an alternative pathway provided by the Slow Arrhenius process (SAP), a molecular mode slower than the structural processes in the liquid state and faster in glass. The SAP, widely observed in polymers, has not yet been reported in small molecules, probably because of the larger experimental difficulties in handling these systems. Here, we report the presence of the SAP in three different molecular glassformers, by investigating these systems in the thin film geometry via dielectric spectroscopy. These results reinforce the idea that the SAP is a universal feature of liquid and glassy dynamics.
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Affiliation(s)
- Federico Caporaletti
- Laboratory of Polymer and Soft Matter Dynamics, Experimental Soft Matter and Thermal Physics (EST), Université libre de Bruxelles (ULB), Brussels 1050, Belgium.
| | - Simone Napolitano
- Laboratory of Polymer and Soft Matter Dynamics, Experimental Soft Matter and Thermal Physics (EST), Université libre de Bruxelles (ULB), Brussels 1050, Belgium.
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12
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Xu J, Bai L, Ren W, Zhu H, Zhou X, Zhang C, Wang X. Flattened chains dominate the adsorption dynamics of loosely adsorbed chains on modified planar substrates. SOFT MATTER 2023; 20:201-211. [PMID: 38078383 DOI: 10.1039/d3sm01339a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Herein, the adsorption of polystyrene (PS) on phenyl-modified SiO2-Si substrates was investigated. Different from those for PS adsorption on a neat SiO2-Si substrate, the growth rate (vads) in the linear regime and hads/Rg (hads, thickness of flattened and loosely adsorbed layers on the substrate; Rg, radius of gyration) declined with increasing molecular weight (Mw) of PS and the phenyl content on the modified substrates, while the thickness of the flattened layer (hflat) and its coverage increased with increasing phenyl content. The results indicated that the adsorption of loose chains was controlled by the adsorption of flattened chains, as it only occurred in the empty contact sites remaining after the adsorption of flattened chains. Before approaching quasi-equilibrium (t < tcross), the number of flattened chain contact sites increased due to an enthalpically favorable process and, correspondingly, their spatial positions dynamically changed, which perturbed the adsorption of loose chains. When the adsorption of flattened chains reached quasi-equilibrium (t > tcross), the adsorption of loose chains was determined by the empty contact sites. The coverage of flattened chains and time to reach quasi-equilibrium were increased with more phenyl groups on the substrate, enhancing π-π interfacial interactions and resulting in a decreased adsorption rate and fewer loosely adsorbed chains. Mw-dependent vads and hads/Rg differed on phenyl-modified substrates compared to the neat SiO2-Si substrate owing to fewer empty contact sites for loose chains. The study findings improve our understanding of the mechanism responsible for the formation and structure of the adsorbed layer on solid surfaces.
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Affiliation(s)
- Jianquan Xu
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, P. R. China.
| | - Lu Bai
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, P. R. China.
| | - Weizhao Ren
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, P. R. China.
| | - Huifeng Zhu
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, P. R. China.
| | - Xianjing Zhou
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, P. R. China.
| | - Cuiyun Zhang
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, P. R. China.
| | - Xinping Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou, 310018, P. R. China.
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13
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Nie W, Douglas JF, Xia W. Competing Effects of Molecular Additives and Cross-Link Density on the Segmental Dynamics and Mechanical Properties of Cross-Linked Polymers. ACS ENGINEERING AU 2023; 3:512-526. [PMID: 38144677 PMCID: PMC10739619 DOI: 10.1021/acsengineeringau.3c00043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/30/2023] [Accepted: 10/06/2023] [Indexed: 12/26/2023]
Abstract
The introduction of molecular additives into thermosets often results in changes in their dynamics and mechanical properties that can have significant ramifications for diverse applications of this broad class of materials such as coatings, high-performance composites, etc. Currently, there is limited fundamental understanding of how such additives influence glass formation in these materials, a problem of broader significance in glass-forming materials. To address this fundamental problem, here, we employ a simplified coarse-grained (CG) model of a polymer network as a model of thermoset materials and then introduce a polymer additive having the same inherent rigidity and polymer-polymer interaction strength as the cross-linked polymer matrix. This energetically "neutral" or "self-plasticizing" additive model gives rise to non-trivial changes in the dynamics of glass formation and provides an important theoretical reference point for the technologically more important case of interacting additives. Based on this rather idealized model, we systematically explore the combined effect of varying the additive mass percentage (m) and cross-link density (c) on the segmental relaxation dynamics and mechanical properties of a model thermoset material with additives. We find that increasing the additive mass percentage m progressively decreases both the glass-transition temperature Tg and the fragility of glass formation, a trend opposite to increasing c so that these thermoset variables clearly have a competing effect on glass formation in these model materials. Moreover, basic mechanical properties (i.e., bulk, shear, and tensile moduli) likewise exhibit a competitive variation with the increase of m and c, which are strongly correlated with the Debye-Waller parameter ⟨u2⟩, a measure of material stiffness at a molecular scale. Our findings prove beneficial in the development of structure-property relationships for the cross-linked polymers, which could help guide the design of such network materials with tailored physical properties.
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Affiliation(s)
- Wenjian Nie
- Department
of Civil, Construction and Environmental Engineering, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Jack F. Douglas
- Materials
Science and Engineering Division, National
Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Wenjie Xia
- Department
of Aerospace Engineering, Iowa State University, Ames, Iowa 50011, United States
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14
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Xu J, Guo X, Guo H, Zhang Y, Wang X. Exploring the Molecular Origin for the Long-Range Propagation of the Substrate Effect in Unentangled Poly(methyl methacrylate) Films. Polymers (Basel) 2023; 15:4655. [PMID: 38139907 PMCID: PMC10748294 DOI: 10.3390/polym15244655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 12/05/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
The polymer/substrate interface plays a significant role in the dynamics of nanoconfined polymers because of its suppression on polymer mobility and its long-range propagation feature, while the molecular origin of the long-range substrate effect in unentangled polymer material is still ambiguous. Herein, we investigated the propagation distances of the substrate effect (h*) by a fluorinated tracer-labeled method of two unentangled polymer films supported on silicon substrates: linear and ring poly(methyl methacrylate) films with relatively low molecular weights. The results indicate that the value of h* has a molecular weight dependence of h*∝N (N is the degree of polymerization) in the unentangled polymer films, while h*∝N1/2 was presented as previously reported in the entangled films. A theoretical model, depending on the polymer/polymer intermolecular interaction, was proposed to describe the above long-range propagation behavior of the substrate effect and agrees with our experiment results very well. From the model, it revealed that the intermolecular friction determines the long-range propagation of the substrate effect in the unentangled system, but the intermolecular entanglement is the dominant role in entangled system. These results give us a deeper understanding of the long-range substrate effect.
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Affiliation(s)
- Jianquan Xu
- Institute for School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China; (X.G.); (H.G.); (Y.Z.)
| | | | | | | | - Xinping Wang
- Institute for School of Chemistry and Chemical Engineering, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China; (X.G.); (H.G.); (Y.Z.)
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15
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Hartley AD, Drayer WF, Ghanekarade A, Simmons DS. Interplay between dynamic heterogeneity and interfacial gradients in a model polymer film. J Chem Phys 2023; 159:204905. [PMID: 38032012 DOI: 10.1063/5.0165650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Glass-forming liquids exhibit long-lived, spatially correlated dynamical heterogeneity, in which some nm-scale regions in the fluid relax more slowly than others. In the nanoscale vicinity of an interface, glass-formers also exhibit the emergence of massive interfacial gradients in glass transition temperature Tg and relaxation time τ. Both of these forms of heterogeneity have a major impact on material properties. Nevertheless, their interplay has remained poorly understood. Here, we employ molecular dynamics simulations of polymer thin films in the isoconfigurational ensemble in order to probe how bulk dynamic heterogeneity alters and is altered by the large gradient in dynamics at the surface of a glass-forming liquid. Results indicate that the τ spectrum at the surface is broader than in the bulk despite being shifted to shorter times, and yet it is less spatially correlated. This is distinct from the bulk, where the τ distribution becomes broader and more spatially organized as the mean τ increases. We also find that surface gradients in slow dynamics extend further into the film than those in fast dynamics-a result with implications for how distinct properties are perturbed near an interface. None of these features track locally with changes in the heterogeneity of caging scale, emphasizing the local disconnect between these quantities near interfaces. These results are at odds with conceptions of the surface as reflecting simply a higher "rheological temperature" than the bulk, instead pointing to a complex interplay between bulk dynamic heterogeneity and spatially organized dynamical gradients at interfaces in glass-forming liquids.
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Affiliation(s)
- Austin D Hartley
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - William F Drayer
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - Asieh Ghanekarade
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - David S Simmons
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
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16
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Jin T, Coley CW, Alexander-Katz A. A Computationally Informed Unified View on the Effect of Polarity and Sterics on the Glass Transition in Vinyl-based Polymer Melts. ACS Macro Lett 2023; 12:1517-1522. [PMID: 37889173 DOI: 10.1021/acsmacrolett.3c00553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
We unveil a unified view on the effect of side chains on the glass transition temperatures (Tg) in polymer melts by using molecular dynamics simulations, density functional theory calculations, and available experimental data. We use acrylates as a model system and evaluate the effect of n-alkyl side chains on Tg. We find that backbone dihedral angle fluctuations follow established patterns due to sterics, as expected. However, we also find that the dihedral angle orthogonal to the backbone, which normally is neglected when discussing the effect on Tg, introduces a secondary rotational degree of freedom which strongly impacts Tg. These results are in agreement with experiments and generalize to multiple other polymer systems, as is demonstrated using available experimental data. Conversely, n-alkyl pendant groups attached to the side group reduce Tg. Our work establishes a coherent framework that unifies previously established trends, emphasizing the polarity and size effects of n-alkyl chains on Tg.
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Affiliation(s)
- Tianyi Jin
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Connor W Coley
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alfredo Alexander-Katz
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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17
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Sarkar J, Madhusudanan M, V C C, Choyal S, Chowdhury M. Roles of aqueous nonsolvents influencing the dynamic stability of poly-( n-butyl methacrylate) thin films at biologically relevant temperatures. SOFT MATTER 2023; 19:8193-8202. [PMID: 37853806 DOI: 10.1039/d3sm00812f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Poly-(n-butyl methacrylate) (PnBMA) is an important polymer in biomedical applications. Here we study the stability of PnBMA thin films prepared on top of slippery silicon substrates and exposed to nonsolvent aqueous incubation media like water and phosphate-buffered saline (PBS) at temperatures relevant to biological applications (37 °C, 25 °C and 4 °C). Dewetting hole growth experiments allowed us to probe the instability in PnBMA films upon incubation followed by thermal annealing. From the early stage of dewetting hole growth dynamics, we inferred that the stability of the thin PnBMA films decreases as a function of the duration and temperature of incubation, even though the films were found not to readily dewet at room temperature after incubation. It is also observed that water incubation makes films more unstable than incubation in PBS. We explained our observations as a combined effect of (i) an increase in surface energy of the PnBMA film due to incubation, (ii) an increased destabilizing effect due to the dominant polar interactions between the incubation medium and the PnBMA film and (iii) the plasticization effect of PnBMA films by the incubation media. Plasticization resulted in a decrease in the modulus of PnBMA thin films as a function of incubation time. The viscosity of PnBMA films upon incubation was found to be coupled to the decreasing modulus. Thus we infer that incubation in common aqueous nonsolvents can detrimentally affect the stability of polymers limiting their specific usages through a complex interplay of multiple molecular level phenomena.
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Affiliation(s)
- Jotypriya Sarkar
- Lab of Soft Interfaces, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, India.
| | - Mithun Madhusudanan
- Lab of Soft Interfaces, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, India.
| | - Chandni V C
- Lab of Soft Interfaces, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, India.
| | - Shilpa Choyal
- Center for Research in Nanotechnology and Science, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Mithun Chowdhury
- Lab of Soft Interfaces, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, India.
- Center for Research in Nanotechnology and Science, Indian Institute of Technology Bombay, Mumbai 400076, India
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18
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Matsuno H, Eto R, Fujii M, Totani M, Tanaka K. Effect of segmental motion on hydrolytic degradation of polyglycolide in electro-spun fiber mats. SOFT MATTER 2023; 19:7459-7467. [PMID: 37750204 DOI: 10.1039/d3sm00613a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Recently, environmentally degradable polymers have received great attention from the perspective of sustaining the aquatic environment. To control the degradation behavior of solid polymer materials in an aqueous phase, it is crucial to better understand the thermal molecular motion of polymer chains in water. We herein focus on polyglycolide (PGA), which is one of the representative aliphatic polyesters that are hydrolytically degradable. Three kinds of fiber mats of PGA with different fiber diameters and comparable crystallinities were prepared using an electrospinning method. Our choice of fiber mats was because the ratio of the surface area, where the hydrolytic degradation starts to occur, to the volume was larger than that for the films. Dynamic mechanical analysis (DMA) enabled us to gain direct access to the dynamic glass transition temperature (Tgα) of PGA in the fiber mats both in dry gaseous nitrogen and liquid water. The Tgα value varied not only with the presence of water molecules, but also with the fiber diameter, or the specific surface area. The degradation behavior of PGA fiber mats was examined by immersing the samples in phosphate-buffered saline at various temperatures. When the segmental motion of PGA in the fiber mats was released, the apparent crystallinity of the mats increased, meaning that PGA amorphous chains were cleaved and thus partially eluted into the aqueous phase. It was also shown that partially cleaved chains crystallized.
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Affiliation(s)
- Hisao Matsuno
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan.
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
| | - Reiki Eto
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan.
| | - Misato Fujii
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan.
| | - Masayasu Totani
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan.
| | - Keiji Tanaka
- Department of Applied Chemistry, Kyushu University, Fukuoka 819-0395, Japan.
- Center for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan
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19
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Di Lisio V, Gallino I, Riegler SS, Frey M, Neuber N, Kumar G, Schroers J, Busch R, Cangialosi D. Size-dependent vitrification in metallic glasses. Nat Commun 2023; 14:4698. [PMID: 37542023 PMCID: PMC10403508 DOI: 10.1038/s41467-023-40417-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 07/26/2023] [Indexed: 08/06/2023] Open
Abstract
Reducing the sample size can profoundly impact properties of bulk metallic glasses. Here, we systematically reduce the length scale of Au and Pt-based metallic glasses and study their vitrification behavior and atomic mobility. For this purpose, we exploit fast scanning calorimetry (FSC) allowing to study glassy dynamics in an exceptionally wide range of cooling rates and frequencies. We show that the main α relaxation process remains size independent and bulk-like. In contrast, we observe pronounced size dependent vitrification kinetics in micrometer-sized glasses, which is more evident for the smallest samples and at low cooling rates, resulting in more than 40 K decrease in fictive temperature, Tf, with respect to the bulk. We discuss the deep implications on how this outcome can be used to convey glasses to low energy states.
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Affiliation(s)
- Valerio Di Lisio
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018, San Sebastián, Spain
| | - Isabella Gallino
- Saarland University, Chair of Metallic Materials, Campus C6.3, 66123, Saarbrücken, Germany.
| | | | - Maximilian Frey
- Saarland University, Chair of Metallic Materials, Campus C6.3, 66123, Saarbrücken, Germany
| | - Nico Neuber
- Saarland University, Chair of Metallic Materials, Campus C6.3, 66123, Saarbrücken, Germany
| | - Golden Kumar
- Department of Mechanical Engineering, University of Texas at Dallas, Richardson, TX, USA
| | - Jan Schroers
- Yale University, Mechanical Engineering and Materials Science, New Haven, CT, USA
| | - Ralf Busch
- Saarland University, Chair of Metallic Materials, Campus C6.3, 66123, Saarbrücken, Germany
| | - Daniele Cangialosi
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018, San Sebastián, Spain.
- Centro de Física de Materiales (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018, San Sebastián, Spain.
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20
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White RP, Lipson JEG. Why Volume and Dynamics Decouple in Nanocomposite Matrices: Space that Cannot Be Accessed is Not Free. PHYSICAL REVIEW LETTERS 2023; 131:018101. [PMID: 37478446 DOI: 10.1103/physrevlett.131.018101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 05/31/2023] [Indexed: 07/23/2023]
Abstract
Polymer nanocomposites have important material applications and are an ongoing focus of many molecular level investigations, however, puzzling experimental results exist. For example, specific volumes for some polymer nanocomposite matrices are 2% to 4% higher than for the neat polymer; in a pure polymer melt this would correspond to a pressure change of 40 to 100 MPa, and a decrease in isothermal segmental relaxation times of 3 to 5 orders of magnitude. However, the nanocomposite segmental dynamics do not show any speed up. We can explain this apparent uncoupling of dynamics from specific volume, and the key is to consider the system expansivity, i.e., the temperature dependence of the volumetric data, together with the concept of limiting volume at close liquid packing. Using pressure, volume, temperature data as a path to both, we are able to predict the effect of nanoadditives on the accessible, i.e., free, space in the material, which is critical for facilitating molecular rearrangements in dense systems. Our analysis explains why an increase in specific volume in a material may not always lead to faster segmental dynamics.
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Affiliation(s)
- Ronald P White
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - Jane E G Lipson
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, USA
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21
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Nakane T, Sasaki T. Thickness Dependence of Segmental Dynamics in Free-Standing Thin Films Predicted by a Dynamically Correlated Network Model. J Phys Chem B 2023. [PMID: 37201178 DOI: 10.1021/acs.jpcb.3c00841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The anomalous dynamics and glass transition behaviors of supercooled liquids under nanoconfinement, such as ultrathin polymer films, have attracted much attention in recent decades. However, a complete elucidation of this mechanism has not yet been achieved. For the dynamics of bulk materials without confinement, we previously proposed a dynamically correlated network (DCN) model, which was found to agree well with the experimental data. The model assumes that segments with thermal fluctuations are dynamically correlated to their neighbors to form string-like clusters, which eventually grow into networks as temperature decreases. In this study, we applied the DCN model to nanoconfined free-standing films by using a simple cubic lattice sandwiched between two free surface layers consisting of virtual "uncorrelated" segments. The average size of DCNs at lower temperatures decreased with decreasing thickness because of confinement. This trend was associated with a decrease in the percolation temperature at which the size of DCN diverges. It was also revealed that the fractal dimension of the generated DCNs exhibits a peak with respect to temperature. The segmental relaxation time for free-standing polystyrene films was evaluated, and the predicted thickness dependence of the glass transition temperature qualitatively agreed with the experimental data. The results suggest that the concept of DCN is compatible with the dynamics of free-standing thin films.
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Affiliation(s)
- Tatsuki Nakane
- Department of Materials Science and Engineering, University of Fukui, Fukui 9108507, Japan
| | - Takashi Sasaki
- Department of Materials Science and Engineering, University of Fukui, Fukui 9108507, Japan
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22
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Omar H, Hidde G, Szymoniak P, Hertwig A, Schönhals A. Growth kinetics of the adsorbed layer of poly(bisphenol A carbonate) and its effect on the glass transition behavior in thin films. RSC Adv 2023; 13:14473-14483. [PMID: 37179996 PMCID: PMC10173819 DOI: 10.1039/d3ra02020g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 05/03/2023] [Indexed: 05/15/2023] Open
Abstract
The glass transition behavior of thin films of poly(bisphenol A carbonate) (PBAC) was studied employing ellipsometry. The glass transition temperature increases with the reduction of the film thickness. This result is attributed to the formation of an adsorbed layer with a reduced mobility compared to bulk PBAC. Therefore, for the first time, the growth kinetics of the adsorbed layer of PBAC was investigated, prepared by leaching samples from a 200 nm thin film which were annealed for several times at three different temperatures. The thickness of each prepared adsorbed layer was measured by multiple scans using atomic force microscopy (AFM). Additionally, an unannealed sample was measured. Comparison of the measurements of the unannealed and the annealed samples provides proof of a pre-growth regime for all annealing temperatures which was not observed for other polymers. For the lowest annealing temperature after the pre-growth stage only a growth regime with a linear time dependence is observed. For higher annealing temperatures the growth kinetics changes from a linear to a logarithmic growth regime at a critical time. At the longest annealing times the films showed signs of dewetting where segments of the adsorbed film were removed from the substrate (dewetting by desorption). The dependence of the surface roughness of the PBAC surface on annealing time also confirmed that the films annealed at highest temperatures for the longest times desorbed from the substrate.
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Affiliation(s)
- Hassan Omar
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
| | - Gundula Hidde
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
| | - Paulina Szymoniak
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
| | - Andreas Hertwig
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
| | - Andreas Schönhals
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
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23
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Hsu HP, Singh MK, Cang Y, Thérien-Aubin H, Mezger M, Berger R, Lieberwirth I, Fytas G, Kremer K. Free Standing Dry and Stable Nanoporous Polymer Films Made through Mechanical Deformation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023:e2207472. [PMID: 37096844 DOI: 10.1002/advs.202207472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 03/09/2023] [Indexed: 05/03/2023]
Abstract
A new straight forward approach to create nanoporous polymer membranes with well defined average pore diameters is presented. The method is based on fast mechanical deformation of highly entangled polymer films at high temperatures and a subsequent quench far below the glass transition temperature Tg . The process is first designed generally by simulation and then verified for the example of polystyrene films. The methodology does not need any chemical processing, supporting substrate, or self assembly process and is solely based on polymer inherent entanglement effects. Pore diameters are of the order of ten polymer reptation tube diameters. The resulting membranes are stable over months at ambient conditions and display remarkable elastic properties.
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Affiliation(s)
- Hsiao-Ping Hsu
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
| | - Manjesh K Singh
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
- Department of Mechanical Engineering, IIT Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Yu Cang
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Zhangwu Road 100, Shanghai, 200092, China
| | - Héloïse Thérien-Aubin
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
- Chemistry Department, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | - Markus Mezger
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, Wien, 1090, Austria
| | - Rüdiger Berger
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
| | - Ingo Lieberwirth
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
| | - George Fytas
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
| | - Kurt Kremer
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128, Mainz, Germany
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24
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Xu WS, Sun ZY. A Thermodynamic Perspective on Polymer Glass Formation. CHINESE JOURNAL OF POLYMER SCIENCE 2023. [DOI: 10.1007/s10118-023-2951-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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25
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Wang M, Li J, Zhang C, Liu G, Napolitano S, Wang D. Physical Aging of Polystyrene Confined in Anodic Aluminum Oxide Nanopores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:3471-3480. [PMID: 36802636 DOI: 10.1021/acs.langmuir.2c03505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We investigated the glassy dynamics of polystyrene (PS) confined in anodic aluminum oxide (AAO) nanopores by differential scanning calorimetry. Based on the outcome of our experiments, we show that the cooling rate applied to process the 2D confined PS melt has a significant impact on both the glass transition and the structural relaxation in the glassy state. A single glass transition temperature (Tg) is observed in quenched samples, while slow-cooled PS chains show two Tgs corresponding to a core-shell structure. The former phenomenon resembles what is observed in freestanding structures, while the latter is imputed to the adsorption of PS onto AAO walls. A more complex picture was drawn for physical aging. In the case of quenched samples, we observed a non-monotonic trend of the apparent aging rate that in 400 nm pores, reaches a value almost twice as larger than what is measured in bulk and decreases upon further confinement in smaller nanopores. For slow-cooled samples, by adequately varying the aging conditions, we were able to control the equilibration kinetics and either separate the two aging processes or induce an intermediate aging regime. We propose a possible explanation of these findings in terms of distribution in free volume and the presence of different aging mechanisms.
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Affiliation(s)
- Ming Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, CAS, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Li
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, CAS, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Chunbo Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, CAS, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Guoming Liu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, CAS, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Simone Napolitano
- Laboratory of Polymer and Soft Matter Dynamics, Experimental Soft Matter and Thermal Physics (EST), Université Libre de Bruxelles (ULB), Brussels 1050, Belgium
| | - Dujin Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, CAS, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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26
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Madhusudanan M, Sarkar J, Dhar S, Chowdhury M. Tuning the Plasticization to Decouple the Effect of Molecular Recoiling Stress from Modulus and Viscosity in Dewetting Thin Polystyrene Films. Macromolecules 2023. [DOI: 10.1021/acs.macromol.2c02093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- Mithun Madhusudanan
- Lab of Soft Interfaces, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India
| | - Jotypriya Sarkar
- Lab of Soft Interfaces, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India
| | - Sudeshna Dhar
- Lab of Soft Interfaces, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India
| | - Mithun Chowdhury
- Lab of Soft Interfaces, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India
- Center for Research in Nano Technology and Science, Indian Institute of Technology Bombay, Mumbai400076, Maharashtra, India
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27
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Li B, Cao PF, Saito T, Sokolov AP. Intrinsically Self-Healing Polymers: From Mechanistic Insight to Current Challenges. Chem Rev 2023; 123:701-735. [PMID: 36577085 DOI: 10.1021/acs.chemrev.2c00575] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Self-healing materials open new prospects for more sustainable technologies with improved material performance and devices' longevity. We present an overview of the recent developments in the field of intrinsically self-healing polymers, the broad class of materials based mostly on polymers with dynamic covalent and noncovalent bonds. We describe the current models of self-healing mechanisms and discuss several examples of systems with different types of dynamic bonds, from various hydrogen bonds to dynamic covalent bonds. The recent advances indicate that the most intriguing results are obtained on the systems that have combined different types of dynamic bonds. These materials demonstrate high toughness along with a relatively fast self-healing rate. There is a clear trade-off relationship between the rate of self-healing and mechanical modulus of the materials, and we propose design principles of polymers toward surpassing this trade-off. We also discuss various applications of intrinsically self-healing polymers in different technologies and summarize the current challenges in the field. This review intends to provide guidance for the design of intrinsic self-healing polymers with required properties.
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Affiliation(s)
- Bingrui Li
- The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee37996, United States.,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37830, United States
| | - Peng-Fei Cao
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing100029, China
| | - Tomonori Saito
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37830, United States
| | - Alexei P Sokolov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee37830, United States.,Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
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28
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Mijangos C, Martin J. Polymerization within Nanoporous Anodized Alumina Oxide Templates (AAO): A Critical Survey. Polymers (Basel) 2023; 15:polym15030525. [PMID: 36771824 PMCID: PMC9919978 DOI: 10.3390/polym15030525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/21/2023] Open
Abstract
In the last few years, the polymerization of monomers within the nanocavities of porous materials has been thoroughly studied and developed, allowing for the synthesis of polymers with tailored morphologies, chemical architectures and functionalities. This is thus a subject of paramount scientific and technological relevance, which, however, has not previously been analyzed from a general perspective. The present overview reports the state of the art on polymerization reactions in spatial confinement within porous materials, focusing on the use of anodized aluminum oxide (AAO) templates. It includes the description of the AAO templates used as nanoreactors. The polymerization reactions are categorized based on the polymerization mechanism. Amongst others, this includes electrochemical polymerization, free radical polymerization, step polymerization and atom transfer radical polymerization (ATRP). For each polymerization mechanism, a further subdivision is made based on the nature of the monomer used. Other aspects of "in situ" polymerization reactions in restricted AAO geometries include: conversion monitoring, kinetic studies, modeling and polymer characterization. In addition to the description of the polymerization process itself, the use of polymer materials derived from polymerization in AAO templates in nanotechnology applications, is also highlighted. Finally, the review is concluded with a general discussion outlining the challenges that remain in the field.
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Affiliation(s)
- Carmen Mijangos
- Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
- Donostia International Physics Center, DIPC, Paseo de Manuel Lardizabal 4, 20018 Donostia-San Sebastian, Spain
- POLYMAT, University of the Basque Country UPV/EHU, Avenida Tolosa 72, 20018 Donostia-San Sebastian, Spain
- Correspondence:
| | - Jaime Martin
- POLYMAT, University of the Basque Country UPV/EHU, Avenida Tolosa 72, 20018 Donostia-San Sebastian, Spain
- Grupo de Polímeros, Centro de Investigacións Tecnolóxicas (CIT), Universidade da Coruña, 15471 Ferrol, Spain
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29
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Yan J, Xu J, Weng LT, Wang F, Wang X, Yuan H, Wang T, Tsui OKC. Glass Transition of the Surface Monolayer of Polystyrene Films with Different Film Thicknesses and Supporting Surfaces. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c02013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Jinsong Yan
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
| | - Jianquan Xu
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou310018, China
| | - Lu-Tao Weng
- Materials Characterization and Preparation Facility (GZ), Advanced Materials Thrust, The Hong Kong University of Science and Technology (Guangzhou), Nansha, Guangzhou511400, Guangdong, China
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
| | - Fengliang Wang
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou310018, China
| | - Xinping Wang
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou310018, China
| | - Hailin Yuan
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
| | - Tong Wang
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
- Department of Materials Science & Engineering, Northwestern University, Evanston, Illinois60208-3120, United States
| | - Ophelia K. C. Tsui
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
- William Mong Institute of Nano Science and Technology, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
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30
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Fractional Coupling of Primary and Johari-Goldstein Relaxations in a Model Polymer. Polymers (Basel) 2022; 14:polym14245560. [PMID: 36559927 PMCID: PMC9787821 DOI: 10.3390/polym14245560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
A polymer model exhibiting heterogeneous Johari−Goldstein (JG) secondary relaxation is studied by extensive molecular-dynamics simulations of states with different temperature and pressure. Time−temperature−pressure superposition of the primary (segmental) relaxation is evidenced. The time scales of the primary and the JG relaxations are found to be highly correlated according to a power law. The finding agrees with key predictions of the Coupling Model (CM) accounting for the decay in a correlation function due to the relaxation and diffusion of interacting systems. Nonetheless, the exponent of the power law, even if it is found in the range predicted by CM (0<ξ<1), deviates from the expected one. It is suggested that the deviation could depend on the particular relaxation process involved in the correlation function and the heterogeneity of the JG process.
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31
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Zheng X, Guo Y, Douglas JF, Xia W. Competing Effects of Cohesive Energy and Cross-Link Density on the Segmental Dynamics and Mechanical Properties of Cross-Linked Polymers. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xiangrui Zheng
- Department of Mechanics, School of Physical Science and Engineering, Beijing Jiaotong Uiversity, Beijing, 100044, China
| | - Yafang Guo
- Department of Mechanics, School of Physical Science and Engineering, Beijing Jiaotong Uiversity, Beijing, 100044, China
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Wenjie Xia
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, Fargo, North Dakota 58108, United States
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32
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Jin T, Hilburg SL, Alexander-Katz A. Glass transition of random heteropolymers: A molecular dynamics simulation study in melt, in water, and in vacuum. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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33
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Wang T, Hu S, Zhang S, Peera A, Reffner J, Torkelson JM. Eliminating the Tg-Confinement Effect in Polystyrene Films: Extraordinary Impact of a 2 mol % 2-Ethylhexyl Acrylate Comonomer. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tong Wang
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Sumeng Hu
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Sipei Zhang
- The Dow Chemical Company, 400 Arcola Road, Collegeville, Pennsylvania19426, United States
| | - Asghar Peera
- The Dow Chemical Company, 400 Arcola Road, Collegeville, Pennsylvania19426, United States
| | - John Reffner
- The Dow Chemical Company, 400 Arcola Road, Collegeville, Pennsylvania19426, United States
| | - John M. Torkelson
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois60208, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
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34
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Wu C. Critical Thicknesses of Free-Standing Thin Films of Molten Polymers: A Multiscale Simulation Study. J Phys Chem B 2022; 126:6500-6510. [PMID: 35979674 DOI: 10.1021/acs.jpcb.2c02627] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The free-standing thin films of melted poly(ethylene oxide) have been extensively simulated by the chemically specific coarse-grained (CG) molecular dynamics (MD) method. It is revealed that if the polymer thin film becomes thinner than some critical value, it would initially turn into a fiber, accompanied by an increase in the free surface area and a decrease in surface tension. A simple but efficient scheme is proposed to determine the critical interfacial thickness and the film thickness from the non-intrinsic density and pressure profiles, and the ratio of the two thicknesses is defined as the interfacial fraction. The critical film thickness is found to increase with the number of chains or equivalently the transverse area. With increasing temperature, the critical interfacial thickness increases a bit whereas the critical film thickness slightly decreases, highlighting the important role of the interfacial fraction. For both of the "critical" and "thick" films, the outermost surface layers are confirmed to undergo the greatest movements. The "critical" film exhibits the intrinsic interfacial thickness and bulk density almost identical to those of the "thick" film, dictating the thickness independence of the surface tension. Therefore, the phase stability of the film is essentially determined from the intrinsic thickness of the bulk layer, and the identified temperature dependence of the critical film thickness can be mainly explained by the surface tension.
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Affiliation(s)
- Chaofu Wu
- Hunan Provincial Key Laboratory of Fine Ceramics and Powder Materials, School of Materials and Environmental Engineering, Hunan University of Humanities, Science and Technology, Loudi 417000, Hunan, P. R. China
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35
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Orellana-Barrasa J, Ferrández-Montero A, Ferrari B, Pastor JY. Natural Ageing of PLA Filaments, Can It Be Frozen? Polymers (Basel) 2022; 14:polym14163361. [PMID: 36015618 PMCID: PMC9416607 DOI: 10.3390/polym14163361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/08/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022] Open
Abstract
The physical ageing of polylactic acid (PLA) is a phenomenon that changes the material’s properties over time. This ageing process is highly dependent on ambient variables, such as temperature and humidity. For PLA, the ageing is noticeable even at room temperatures, a process commonly referred to as natural ageing. Stopping the ageing by freezing the material can be helpful to preserve the properties of the PLA and stabilise it at any time during its storage until it is required for testing. However, it is essential to demonstrate that the PLA’s mechanical properties are not degraded after defrosting the samples. Four different methods for stopping the ageing (anti-ageing processes) are analysed in this paper—all based on freezing and defrosting the PLA samples. We determine the temperature and ambient water vapor influence during the freezing and defrosting process using desiccant and zip bags. The material form selected is PLA filaments (no bulk material or scaffold structures) printed at 190 °C with diameters between 400 and 550 µm and frozen at −24 °C in the presence or absence of a desiccant. The impact of the anti-ageing processes on PLA’s ageing and mechanical integrity is studied regarding the thermal, mechanical and fractographical properties. In conclusion, an anti-ageing process is defined to successfully stop the natural ageing of the PLA for an indefinite length of time. This process does not affect the mechanical properties or the structural integrity of the PLA. As a result, large quantities of this material can be produced in a single batch and be safely stored to be later characterised under the same manufacturing and ageing conditions, which is currently a limiting factor from an experimental point of view as polymeric filament properties can show significant variety from batch to batch.
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Affiliation(s)
- Jaime Orellana-Barrasa
- Centro de Investigación en Materiales Estructurales (CIME), Universidad Politécnica de Madrid, 28040 Madrid, Spain
- Correspondence:
| | | | - Begoña Ferrari
- Instituto de Cerámica y Vidrio (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
| | - José Ygnacio Pastor
- Centro de Investigación en Materiales Estructurales (CIME), Universidad Politécnica de Madrid, 28040 Madrid, Spain
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36
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Zheng X, Guo Y, Douglas JF, Xia W. Understanding the role of cross-link density in the segmental dynamics and elastic properties of cross-linked thermosets. J Chem Phys 2022; 157:064901. [PMID: 35963735 DOI: 10.1063/5.0099322] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cross-linking is known to play a pivotal role in the relaxation dynamics and mechanical properties of thermoset polymers, which are commonly used in structural applications because of their light weight and inherently strong nature. Here, we employ a coarse-grained (CG) polymer model to systematically explore the effect of cross-link density on basic thermodynamic properties as well as corresponding changes in the segmental dynamics and elastic properties of these network materials upon approaching their glass transition temperatures (Tg). Increasing the cross-link density unsurprisingly leads to a significant slowing down of the segmental dynamics, and the fragility K of glass formation shifts in lockstep with Tg, as often found in linear polymer melts when the polymer mass is varied. As a consequence, the segmental relaxation time τα becomes almost a universal function of reduced temperature, (T - Tg)/Tg, a phenomenon that underlies the applicability of the "universal" Williams-Landel-Ferry (WLF) relation to many polymer materials. We also test a mathematical model of the temperature dependence of the linear elastic moduli based on a simple rigidity percolation theory and quantify the fluctuations in the local stiffness of the network material. The moduli and distribution of the local stiffness likewise exhibit a universal scaling behavior for materials having different cross-link densities but fixed (T - Tg)/Tg. Evidently, Tg dominates both τα and the mechanical properties of our model cross-linked polymer materials. Our work provides physical insights into how the cross-link density affects glass formation, aiding in the design of cross-linked thermosets and other structurally complex glass-forming materials.
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Affiliation(s)
- Xiangrui Zheng
- Department of Mechanics, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, China
| | - Yafang Guo
- Department of Mechanics, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, China
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Wenjie Xia
- Department of Civil, Construction and Environmental Engineering, North Dakota State University, Fargo, North Dakota 58108, USA
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37
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Xu J, Wang X, Chen L, Ao W, Zuo B, Zhang C, Wang X. Spatially Heterogeneous Dynamics in Supported Ultrathin Poly(ethylene terephthalate) Films Depend on the Thicknesses of the Film and the Adsorbed Layer. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jianquan Xu
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Xin Wang
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Liang Chen
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Wentao Ao
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Biao Zuo
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Cuiyun Zhang
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Xinping Wang
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China
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38
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Ihara Y, Yamagishi H, Lin C, Jhu CH, Tsai MC, Horie M, Yamamoto Y. Hydrothermal crosslinking of poly(fluorenylamine) with styryl side chains to produce insoluble fluorescent microparticles. Polym J 2022. [DOI: 10.1038/s41428-022-00679-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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39
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Kardasis P, Sakellariou G, Steinhart M, Floudas G. Non-equilibrium Effects of Polymer Dynamics under Nanometer Confinement: Effects of Architecture and Molar Mass. J Phys Chem B 2022; 126:5570-5581. [PMID: 35834553 DOI: 10.1021/acs.jpcb.2c03389] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The non-equilibrium dynamics of linear and star-shaped cis-1,4 polyisoprenes confined within nanoporous alumina is explored as a function of pore size, d, molar mass, and functionality (f = 2, 6, and 64). Two thermal protocols are tested: one resembling a quasi-static process (I) and another involving fast cooling followed by annealing (II). Although both protocols give identical equilibrium times, it is through protocol I that it is easier to extract the equilibrium times, teq, by the linear relationships of the characteristic peak frequencies with time and rate, respectively, as log(fmax) = C1 - k log(t) and log(fmax) = C2 + λ log(β). Both thermal protocols establish the existence of a critical temperature (at Tc, where k → 0 and λ → 0) below which non-equilibrium effects set-in. The critical temperature depends on the degree of confinement, 2Rg/d, and on molecular architecture. Strikingly, establishing equilibrium dynamics at all temperatures above the bulk, Tg, requires 2Rg/d ∼ 0.02, i.e., pore diameters that are much larger than the chain dimensions. This reflects non-equilibrium configurations of the adsorbed layer that extent away from the pore walls. The equilibrium times depend strongly on temperature, pore size, and functionality. In general, star-shaped polymers require longer times to reach equilibrium because of the higher tendency for adsorption. Both thermal protocols produced an increasing dielectric strength for the segmental and chain modes. The increase was beyond any densification, suggesting enhanced orientation correlations of subchain dipoles.
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Affiliation(s)
| | - Georgios Sakellariou
- Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece
| | - Martin Steinhart
- Institut für Chemie neuer Materialien, Universität Osnabrück, D-49069 Osnabrück, Germany
| | - George Floudas
- Department of Physics, University of Ioannina, 45110 Ioannina, Greece.,Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 45110 Ioannina, Greece
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40
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Drayer WF, Simmons DS. Sequence Effects on the Glass Transition of a Model Copolymer System. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- William F. Drayer
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida 33620, United States
| | - David S. Simmons
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida 33620, United States
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41
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Jin T, Coley CW, Alexander-Katz A. Molecular signatures of the glass transition in polymers. Phys Rev E 2022; 106:014506. [PMID: 35974655 DOI: 10.1103/physreve.106.014506] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
The glass transition temperature (T_{g}) is one of the most fundamental properties of polymers. T_{g} is predicted by some theories as a sudden change in a "macroscopic" quantity (e.g., compressibility). However, for systems with "soft" glass transitions where the change is gradual it becomes hard to pinpoint precisely the transition temperature as well as the set of molecular changes occurring during this transition. Here, we introduce two new molecular signatures for the glass transition of polymers that exhibit clear changes as one approaches T_{g}: (i) differential change of the probability distribution of dihedral angles as a function of temperature and (ii) the distribution of fractional of the time spent in the different torsional states. These new signatures provide insights into the glass transition in polymers by directly exhibiting the concept of spatial heterogeneity and dynamical ergodicity breaking in such systems, as well as provide a key step to quantitatively obtain the transition temperature from molecular characteristics of the polymeric systems.
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Affiliation(s)
- Tianyi Jin
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Connor W Coley
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Alfredo Alexander-Katz
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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42
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Chowdhury M, Monnier X, Cangialosi D, Priestley RD. Decoupling of Glassy Dynamics from Viscosity in Thin Supported Poly( n-butyl methacrylate) Films. ACS POLYMERS AU 2022; 2:333-340. [PMID: 36267547 PMCID: PMC9576260 DOI: 10.1021/acspolymersau.2c00010] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
We utilized fast
scanning calorimetry to characterize the glass
transition temperature (Tg) and intrinsic
molecular mobility of low-molecular-weight poly(n-butyl methacrylate) thin films of varying thicknesses. We found
that the Tg and intrinsic molecular mobility
were coupled, showing no film thickness-dependent variation. We further
employed a unique noncontact capillary nanoshearing technique to directly
probe layer-resolved gradients in the rheological response of these
films. We found that layer-resolved shear mobility was enhanced with
a reduction in film thickness, whereas the effective viscosity decreased.
Our results highlight the importance of polymer–substrate attractive
interactions and free surface-promoted enhanced mobility, establishing
a competitive nanoconfinement effect in poly(n-butyl
methacrylate) thin films. Moreover, the findings indicate a decoupling
in the thickness-dependent variation of Tg and intrinsic molecular mobility with the mechanical responses (shear
mobility and effective viscosity).
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Affiliation(s)
- Mithun Chowdhury
- Lab of Soft Interfaces, Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, India
- Center for Research in Nanotechnology and Science, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Xavier Monnier
- Centro de Física de Materiales (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain
| | - Daniele Cangialosi
- Centro de Física de Materiales (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain
| | - Rodney D. Priestley
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
- Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08540, United States
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43
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Xing Z, Zhu N, Yang Y, Wang X, Zuo B. Alternating chain sequence weakening of interfacial molecular interactions enhances the Tg confinement effect of polymers. Polym J 2022. [DOI: 10.1038/s41428-022-00672-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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Lindemann N, Schawe JEK, Lacayo-Pineda J. Kinetics of the Glass Transition of Silica-Filled Styrene-Butadiene Rubber: The Effect of Resins. Polymers (Basel) 2022; 14:polym14132626. [PMID: 35808677 PMCID: PMC9269213 DOI: 10.3390/polym14132626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/09/2022] [Accepted: 06/24/2022] [Indexed: 11/16/2022] Open
Abstract
Resins are important for enhancing both the processability and performance of rubber. Their efficient utilization requires knowledge about their influence on the dynamic glass transition and their miscibility behavior in the specific rubber compound. The resins investigated, poly-(α-methylstyrene) (AMS) and indene-coumarone (IC), differ in molecular rigidity but have a similar aromaticity degree and glass transition temperature. Transmission electron microscopy (TEM) investigations show an accumulation of IC around the silanized silica in styrene–butadiene rubber (SBR) at high contents, while AMS does not show this effect. This higher affinity between IC and the silica surface leads to an increased compactness of the filler network, as determined by dynamic mechanical analysis (DMA). The influence of the resin content on the glass transition of the rubber compounds is evaluated in the sense of the Gordon–Taylor equation and suggests a rigid amorphous fraction for the accumulated IC. Broadband dielectric spectroscopy (BDS) and fast differential scanning calorimetry (FDSC) are applied for the characterization of the dielectric and thermal relaxations as well as for the corresponding vitrification kinetics. The cooling rate dependence of the vitrification process is combined with the thermal and dielectric relaxation time by one single Vogel–Fulcher–Tammann–Hesse equation, showing an increased fragility of the rubber containing AMS.
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Affiliation(s)
- Niclas Lindemann
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover, Callinstraße 3A, 30167 Hanover, Germany
- Continental Reifen Deutschland GmbH, Jädekamp 30, 30419 Hanover, Germany;
- Correspondence:
| | | | - Jorge Lacayo-Pineda
- Continental Reifen Deutschland GmbH, Jädekamp 30, 30419 Hanover, Germany;
- Institut für Anorganische Chemie, Leibniz Universität Hannover, Callinstraße 9, 30167 Hanover, Germany
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45
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Reiter G, Ramezani F, Baschnagel J. The memory of thin polymer films generated by spin coating. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2022; 45:51. [PMID: 35612618 PMCID: PMC9132827 DOI: 10.1140/epje/s10189-022-00205-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
We present results from isothermal and temperature-sweep creep experiments adapted to filaments which were derived from spin coated and subsequently crumpled thin polystyrene films. Due to the existence of residual stresses induced by preparation, the filaments showed significant shrinkage which we followed as a function of time at various temperatures. In addition, the influence of preparation conditions and subsequent annealing of supported thin polymer films on shrinkage and relaxation behavior was investigated. The temporal evolution of shrinkage revealed a sequence of relaxation regimes. We explored the temperature dependence of this relaxation and compared our observations with published results on drawn melt-spun fibers. This comparison revealed intriguing similarities between both systems prepared along different pathways. For instance, the magnitudes of shrinkage of melt-spun fibers and of filaments from crumpled spin coated polymer films are similar. Thus, our results suggest the existence of generic mechanisms of "forgetting", i.e., how non-equilibrated polymers lose their memory of past processing events.
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Affiliation(s)
- Günter Reiter
- Institute of Physics, Albert-Ludwigs-Universität Freiburg, 79104, Freiburg, Germany.
| | - Farzad Ramezani
- Institute of Physics, Albert-Ludwigs-Universität Freiburg, 79104, Freiburg, Germany
| | - Jörg Baschnagel
- Institut Charles Sadron, Université de Strasbourg and CNRS, 67034, Strasbourg Cedex, France
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46
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Qiang Y, Pande SS, Lee D, Turner KT. The Interplay of Polymer Bridging and Entanglement in Toughening Polymer-Infiltrated Nanoparticle Films. ACS NANO 2022; 16:6372-6381. [PMID: 35380037 DOI: 10.1021/acsnano.2c00471] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Polymer-nanoparticle composite films (PNCFs) with high loadings of nanoparticles (NPs) (>50 vol %) have applications in multiple areas, and an understanding of their mechanical properties is essential for their broader use. The high-volume fraction and small size of the NPs lead to physical confinement of the polymers that can drastically change the properties of polymers relative to the bulk. We investigate the fracture behavior of a class of highly loaded PNCFs prepared by polymer infiltration into NP packings. These polymer-infiltrated nanoparticle films (PINFs) have applications as multifunctional coatings and membranes and provide a platform to understand the behavior of polymers that are highly confined. Here, the extent of confinement in PINFs is tuned from 0.1 to 44 and the fracture toughness of PINFs is increased by up to a factor of 12 by varying the molecular weight of the polymers over 3 orders of magnitude and using NPs with diameters ranging from 9 to 100 nm. The results show that brittle, low molecular weight (MW) polymers can significantly toughen NP packings, and this toughening effect becomes less pronounced with increasing NP size. In contrast, high MW polymers capable of forming interchain entanglements are more effective in toughening large NP packings. We propose that confinement has competing effects of polymer bridging increasing toughness and chain disentanglement decreasing toughness. These findings provide insight into the fracture behavior of confined polymers and will guide the development of mechanically robust PINFs as well as other highly loaded PNCFs.
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47
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Winkler R, Chat K, Unni AB, Dulski M, Laskowska M, Laskowski L, Adrjanowicz K. Glass Transition Dynamics of Poly(phenylmethylsiloxane) Confined within Alumina Nanopores with Different Atomic Layer Deposition (ALD) Coatings. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Roksana Winkler
- Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
- Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Katarzyna Chat
- Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
- Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Aparna Beena Unni
- Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
- Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
| | - Mateusz Dulski
- Institute of Materials Engineering, University of Silesia in Katowice, 40-007 Katowice, Poland
| | - Magdalena Laskowska
- Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakow, Poland
| | - Lukasz Laskowski
- Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakow, Poland
| | - Karolina Adrjanowicz
- Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
- Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
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48
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Sasaki T. Polymer Dynamics: Bulk and Nanoconfined Polymers. Polymers (Basel) 2022; 14:polym14071271. [PMID: 35406145 PMCID: PMC9002963 DOI: 10.3390/polym14071271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 11/28/2022] Open
Affiliation(s)
- Takashi Sasaki
- Department of Materials Science and Engineering, University of Fukui, Fukui 910-8507, Japan
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49
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Jaeger TD, Simmons DS. Temperature dependence of aging dynamics in highly non-equilibrium model polymer glasses. J Chem Phys 2022; 156:114504. [DOI: 10.1063/5.0080717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A central feature of the non-equilibrium glassy “state” is its tendency to age toward equilibrium, obeying signatures identified by Kovacs over 50 years ago. The origin of these signatures, their fate far from equilibrium and at high temperatures, and the underlying nature of the glassy “state” far from equilibrium remain unsettled. Here, we simulate physical aging of polymeric glasses, driven much farther from equilibrium and at much higher temperatures than possible in experimental melt-quenched glasses. While these glasses exhibit Kovacs’ signatures of glassy aging at sufficiently low temperatures, these signatures disappear above the onset TA of non-Arrhenius equilibrium dynamics, suggesting that TA demarcates an upper bound to genuinely glassy states. Aging times in glasses after temperature up-jumps are found to obey an Arrhenius law interpolating between equilibrium dynamics at TA and at the start of the temperature up-jump, providing a zero-parameter rule predicting their aging behavior and identifying another unrecognized centrality of TA to aging behavior. This differs qualitatively from behavior of our glasses produced by temperature down-jumps, which exhibit a fractional power law decoupling relation with equilibrium dynamics. While the Tool–Narayanaswamy–Moynihan model can predict the qualitative single-temperature behavior of these systems, we find that it fails to predict the disappearance of Kovacs signatures above TA and the temperature dependence of aging after large temperature up-jumps. These findings highlight a need for new theoretical insights into the aging behavior of glasses at ultra-high fictive temperatures and far from equilibrium.
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Affiliation(s)
- Tamara D. Jaeger
- Department of Polymer Engineering, The University of Akron, Akron, Ohio 44325, USA
| | - David S. Simmons
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida 33620, USA
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50
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McKenzie I, Fujimoto D, Karner VL, Li R, MacFarlane WA, McFadden RML, Morris GD, Pearson MR, Raegen AN, Stachura M, Ticknor JO, Forrest JA. A β-NMR study of the depth, temperature, and molecular-weight dependence of secondary dynamics in polystyrene: Entropy–enthalpy compensation and dynamic gradients near the free surface. J Chem Phys 2022; 156:084903. [DOI: 10.1063/5.0081185] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigated the depth, temperature, and molecular-weight (MW) dependence of the γ-relaxation in polystyrene glasses using implanted 8Li+ and β-detected nuclear magnetic resonance. Measurements were performed on thin films with MW ranging from 1.1 to 641 kg/mol. The temperature dependence of the average 8Li spin–lattice relaxation time [Formula: see text] was measured near the free surface and in the bulk. Spin–lattice relaxation is caused by phenyl ring flips, which involve transitions between local minima over free-energy barriers with enthalpic and entropic contributions. We used transition state theory to model the temperature dependence of the γ-relaxation, and hence [Formula: see text]. There is no clear correlation of the average entropy of activation [Formula: see text] and enthalpy of activation [Formula: see text] with MW, but there is a clear correlation between [Formula: see text] and [Formula: see text], i.e., entropy–enthalpy compensation. This results in the average Gibbs energy of activation, [Formula: see text], being approximately independent of MW. Measurements of the temperature dependence of [Formula: see text] as a function of depth below the free surface indicate the inherent entropic barrier, i.e., the entropy of activation corresponding to [Formula: see text] = 0, has an exponential dependence on the distance from the free surface before reaching the bulk value. This results in [Formula: see text] near the free surface being lower than the bulk. Combining these observations results in a model where the average fluctuation rate of the γ-relaxation has a “double-exponential” depth dependence. This model can explain the depth dependence of [Formula: see text] in polystyrene films. The characteristic length of enhanced dynamics is ∼6 nm and approximately independent of MW near room temperature.
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Affiliation(s)
- Iain McKenzie
- TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Derek Fujimoto
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Victoria L. Karner
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Ruohong Li
- TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
| | - W. Andrew MacFarlane
- TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Ryan M. L. McFadden
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | | | - Matthew R. Pearson
- Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
| | - Adam N. Raegen
- TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | | | - John O. Ticknor
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - James A. Forrest
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada
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