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Cheng R, Wang Y, Men R, Lei Z, Song J, Li Y, Guo M. High-energy-density polymer dielectrics via compositional and structural tailoring for electrical energy storage. iScience 2022; 25:104837. [PMID: 35996580 PMCID: PMC9391588 DOI: 10.1016/j.isci.2022.104837] [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] [Indexed: 11/18/2022] Open
Abstract
Dielectric capacitors with higher working voltage and power density are favorable candidates for renewable energy systems and pulsed power applications. A polymer with high breakdown strength, low dielectric loss, great scalability, and reliability is a preferred dielectric material for dielectric capacitors. However, their low dielectric constant limits the polymer to achieve satisfying energy density. Therefore, great efforts have been made to get high-energy-density polymer dielectrics. By compositional and structural tailoring, the synergic integrations of the multiple components and optimized structural design effectively improved the energy storage properties. This review presents an overview of recent advancements in the field of high-energy-density polymer dielectrics via compositional and structural tailoring. The surface/interfacial engineering conducted on both microscale and macroscale for polymer dielectrics is the focus of this review. Challenges and the promising opportunities for the development of polymer dielectrics for capacitive energy storage applications are presented at the end of this review. A detailed summary of the state-of-the-art polymer dielectrics The comparison of polymer nanocomposites with 0D, 1D, and 2D nanofillers Analyzing high Ue polymer dielectrics via compositional and structural tailoring Summary of micro- or macro-surface and interface engineering
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Arabeche K, Delbreilh L, Baer E. Physical aging of multilayer polymer films—influence of layer thickness on enthalpy relaxation process, effect of confinement. JOURNAL OF POLYMER RESEARCH 2021. [DOI: 10.1007/s10965-021-02809-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ngai KL, Wojnarowska Z, Paluch M. The structural α-relaxation times of prilocaine confined in 1 nm pores of molecular sieves: quantitative explanation by the coupling model. Phys Chem Chem Phys 2020; 22:9257-9261. [PMID: 32307500 DOI: 10.1039/d0cp00282h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The molecular glass-former and pharmaceutical, prilocaine, distinguishes itself by exhibiting seven general and fundamental dynamic and thermodynamic properties [Z. Wojnarowska, et al., J. Phys. Chem. B, 2015, 39, 12699.], all of which have been explained using the coupling model. What has not been studied before are the changes in properties of the structural α-relaxation of prilocaine when subjected to extreme nano-confinement in spaces with a size of about 1 nm. Recently, Ruis et al. [G. N. Ruiz, et al., Phys. Chem. Chem. Phys., 2019, 21, 15576.] measured the α-relaxation times, τα,conf(T), of prilocaine confined in 1 nm pores of molecular sieves. They found that τα,conf(T) are significantly reduced from those of bulk prilocaine, τα,bulk(T), and assume a weaker temperature dependence. The data in toto pose a challenge for any theory of glass transition to explain quantitatively. The coupling model (CM) was applied to this problem to predict the α-relaxation times of prilocaine when cooperativity is removed, which is expected because only a few prilocaine molecules can fit into the 1 nm pores. The results from the CM are in quantitative agreement with the experimental values of τα,conf(T) and the temperature dependence. The success is nontrivial because no other extant theory can do the same to the best of our knowledge.
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Affiliation(s)
- K L Ngai
- CNR-IPCF, Dipartimento di Fisica, Largo Bruno Pontecorvo 3, I-56127, Pisa, Italy.
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Ngai KL, Lunkenheimer P, Loidl A. Predicting the α-relaxation time of glycerol confined in 1.16 nm pores of zeolitic imidazolate frameworks. Phys Chem Chem Phys 2020; 22:507-511. [PMID: 31825416 DOI: 10.1039/c9cp05270d] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Uhl et al. [J. Chem. Phys., 2019, 150, 024504] studied the molecular dynamics of glycerol confined in a microporous zeolitic imidazolate framework (ZIF-8) with well-defined pore diameters of 1.16 nm by broadband dielectric spectroscopy. Of interest is a fast process in the central part of the pores identified as the α-relaxation of the confined supercooled glycerol with relaxation times τα,conf(T) reduced from τα,bulk(T) of bulk glycerol and having a temperature dependence different from the super-Arrhenius temperature of the latter. The focus of Uhl et al. was relating the confined molecular dynamics to the cooperativity length scales Lcorr(T) of molecular motion above the glass transition, and deducing the limiting high-temperature value of the correlation length of about 1.22 nm. Not yet considered by anyone are the observed values of τα,conf(T) and temperature dependence. Since the cooperativity length scales Lcorr(T) were found to be larger than the pore size of ZIF-8 over the temperature range studied and the density of the glycerol in the pore is possibly lower than the bulk, the cooperativity of the α-relaxation of glycerol confined in ZIF-8 is drastically reduced. Thus, within the framework of the Coupling Model (CM), τα,conf(T) should be nearly the same as the primitive relaxation time τ0(T) for glycerol when devoid of intermolecular coupling and cooperativity. Consistent with the absence of cooperativity of the glycerol confined in ZIF-8, we find the calculated τα,conf(T) are either the same or slightly longer than the calculated values of τ0(T). The quantitative prediction of the CM is verified. At this time we know of no other theory that can make such a quantitative prediction.
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Affiliation(s)
- K L Ngai
- CNR-IPCF, Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy.
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Yoon H, McKenna GB. Dynamic and temperature dependent response of physical vapor deposited Se in freely standing nanometric thin films. J Chem Phys 2016; 144:184501. [DOI: 10.1063/1.4948322] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Heedong Yoon
- Department of Chemical Engineering, Whitacre College of Engineering, Texas Tech University, Lubbock, Texas 79409-4121, USA
| | - Gregory B. McKenna
- Department of Chemical Engineering, Whitacre College of Engineering, Texas Tech University, Lubbock, Texas 79409-4121, USA
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Varnik F, Franosch T. Non-monotonic effect of confinement on the glass transition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:133001. [PMID: 26940539 DOI: 10.1088/0953-8984/28/13/133001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The relaxation dynamics of glass forming liquids and their structure are influenced in the vicinity of confining walls. This effect has mostly been observed to be a monotonic function of the slit width. Recently, a qualitatively new behaviour has been uncovered by Mittal and coworkers, who reported that the single particle dynamics in a hard-sphere fluid confined in a planar slit varies in a non-monotonic way as the slit width is decreased from five to roughly two particle diametres (Mittal et al 2008 Phys. Rev. Lett. 100 145901). In view of the great potential of this effect for applications in those fields of science and industry, where liquids occur under strong confinement (e.g. nano-technology), the number of researchers studying various aspects and consequences of this non-monotonic behaviour has been rapidly growing. This review aims at providing an overview of the research activity in this newly emerging field. We first briefly discuss how competing mechanisms such as packing effects and short-range attraction may lead to a non-monotonic glass transition scenario in the bulk. We then analyse confinement effects on the dynamics of fluids using a thermodynamic route which relates the single particle dynamics to the excess entropy. Moreover, relating the diffusive dynamics to the Widom's insertion probability, the oscillations of the local dynamics with density at moderate densities are fairly well described. At high densities belonging to the supercooled regime, however, this approach breaks down signaling the onset of strongly collective effects. Indeed, confinement introduces a new length scale which in the limit of high densities and small pore sizes competes with the short-range local order of the fluid. This gives rise to a non-monotonic dependence of the packing structure on confinement, with a corresponding effect on the dynamics of structural relaxation. This non-monotonic effect occurs also in the case of a cone-plate type channel, where the degree of confinement varies with distance from the apex. This is a very promising issue for future research with the possibility of uncovering the existence of alternating glassy and liquid-like domains.
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Affiliation(s)
- Fathollah Varnik
- Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
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Xie SJ, Qian HJ, Lu ZY. The glass transition of polymers with different side-chain stiffness confined in free-standing thin films. J Chem Phys 2015; 142:074902. [DOI: 10.1063/1.4908047] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Shi-Jie Xie
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
| | - Hu-Jun Qian
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
| | - Zhong-Yuan Lu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
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8
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Xie SJ, Qian HJ, Lu ZY. Hard and soft confinement effects on the glass transition of polymers confined to nanopores. POLYMER 2015. [DOI: 10.1016/j.polymer.2014.11.049] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Sha Y, Li L, Wang X, Wan Y, Yu J, Xue G, Zhou D. Growth of Polymer Nanorods with Different Core–Shell Dynamics via Capillary Force in Nanopores. Macromolecules 2014. [DOI: 10.1021/ma5017715] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Ye Sha
- Department
of Polymer Science and Engineering, School of Chemistry and Chemical
Engineering, Key Laboratory of High Performance Polymer Materials
and Technology (Nanjing University), Ministry of Education, State
Key Laboratory of Coordination Chemistry, Nanjing National Laboratory
of Microstructure, Nanjing University, Nanjing 210093, P. R. China
| | - Linling Li
- Department
of Polymer Science and Engineering, School of Chemistry and Chemical
Engineering, Key Laboratory of High Performance Polymer Materials
and Technology (Nanjing University), Ministry of Education, State
Key Laboratory of Coordination Chemistry, Nanjing National Laboratory
of Microstructure, Nanjing University, Nanjing 210093, P. R. China
| | - Xiaoliang Wang
- Department
of Polymer Science and Engineering, School of Chemistry and Chemical
Engineering, Key Laboratory of High Performance Polymer Materials
and Technology (Nanjing University), Ministry of Education, State
Key Laboratory of Coordination Chemistry, Nanjing National Laboratory
of Microstructure, Nanjing University, Nanjing 210093, P. R. China
| | - Yuanxin Wan
- Department
of Polymer Science and Engineering, School of Chemistry and Chemical
Engineering, Key Laboratory of High Performance Polymer Materials
and Technology (Nanjing University), Ministry of Education, State
Key Laboratory of Coordination Chemistry, Nanjing National Laboratory
of Microstructure, Nanjing University, Nanjing 210093, P. R. China
| | - Jie Yu
- Department
of Polymer Science and Engineering, School of Chemistry and Chemical
Engineering, Key Laboratory of High Performance Polymer Materials
and Technology (Nanjing University), Ministry of Education, State
Key Laboratory of Coordination Chemistry, Nanjing National Laboratory
of Microstructure, Nanjing University, Nanjing 210093, P. R. China
| | - Gi Xue
- Department
of Polymer Science and Engineering, School of Chemistry and Chemical
Engineering, Key Laboratory of High Performance Polymer Materials
and Technology (Nanjing University), Ministry of Education, State
Key Laboratory of Coordination Chemistry, Nanjing National Laboratory
of Microstructure, Nanjing University, Nanjing 210093, P. R. China
| | - Dongshan Zhou
- Department
of Polymer Science and Engineering, School of Chemistry and Chemical
Engineering, Key Laboratory of High Performance Polymer Materials
and Technology (Nanjing University), Ministry of Education, State
Key Laboratory of Coordination Chemistry, Nanjing National Laboratory
of Microstructure, Nanjing University, Nanjing 210093, P. R. China
- School
of Physical Science and Technology, Xinjiang Laboratory of Phase
Transitions and Microstructures
in Condensed Matters, Yili Normal University, Yining 835000, P. R. China
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Chen J, Li L, Zhou D, Xu J, Xue G. Effect of Molecular Chain Architecture on Dynamics of Polymer Thin Films Measured by the Ac-Chip Calorimeter. Macromolecules 2014. [DOI: 10.1021/ma500188b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Jiao Chen
- Department of Polymer
Science
and Engineering, School of Chemistry and Chemical Engineering, Key
Laboratory of High Performance Polymer Materials and Technology (Nanjing
University), Ministry of Education, Nanjing University, Nanjing 210093 P. R. China
| | - Linling Li
- Department of Polymer
Science
and Engineering, School of Chemistry and Chemical Engineering, Key
Laboratory of High Performance Polymer Materials and Technology (Nanjing
University), Ministry of Education, Nanjing University, Nanjing 210093 P. R. China
| | - Dongshan Zhou
- Department of Polymer
Science
and Engineering, School of Chemistry and Chemical Engineering, Key
Laboratory of High Performance Polymer Materials and Technology (Nanjing
University), Ministry of Education, Nanjing University, Nanjing 210093 P. R. China
| | - Jie Xu
- Department of Polymer
Science
and Engineering, School of Chemistry and Chemical Engineering, Key
Laboratory of High Performance Polymer Materials and Technology (Nanjing
University), Ministry of Education, Nanjing University, Nanjing 210093 P. R. China
| | - Gi Xue
- Department of Polymer
Science
and Engineering, School of Chemistry and Chemical Engineering, Key
Laboratory of High Performance Polymer Materials and Technology (Nanjing
University), Ministry of Education, Nanjing University, Nanjing 210093 P. R. China
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Prevosto D, Capaccioli S, Ngai KL. Origins of the two simultaneous mechanisms causing glass transition temperature reductions in high molecular weight freestanding polymer films. J Chem Phys 2014; 140:074903. [DOI: 10.1063/1.4865752] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Capaccioli S, Ngai KL, Paluch M, Prevosto D. Mechanism of fast surface self-diffusion of an organic glass. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:051503. [PMID: 23214785 DOI: 10.1103/physreve.86.051503] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 09/27/2012] [Indexed: 06/01/2023]
Abstract
Zhu et al. [L. Zhu, C. W. Brian, S. F. Swallen, P. T. Straus, M. D. Ediger, and L. Yu, Phys. Rev. Lett. 106, 256103 (2011)] measured the surface self-diffusion for an organic glass former, indomethacin, and found surface diffusion is more than 10(6) times faster than bulk diffusion at temperatures around T(g). With the help of dielectric relaxation and differential scanning calorimetry measurements on bulk indomethacin, and analysis of the data using the coupling model, we provide a quantitative explanation. We find the bulk α-relaxation time is longer than the primitive relaxation time also by about six orders of magnitude in a range of temperature above and below the bulk T(g). Thus, the cause of the fast surface diffusion is the nearly vanishing of intermolecular coupling of relaxation and diffusion at the surface. The results of related experimental studies of enhanced relaxation and diffusion at the surface of other glass formers also have been analyzed and quantitatively explained. Our predictions on surface diffusion from the coupling model are compared with that given by the random first order transition theory.
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Affiliation(s)
- S Capaccioli
- Physics Department, University of Pisa, Largo B Pontecorvo 3, I-56127 Pisa, Italy
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Ngai KL, Prevosto D, Grassia L. Viscoelasticity of nanobubble-inflated ultrathin polymer films: Justification by the coupling model. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/polb.23201] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Xu J, Li D, Chen J, Din L, Wang X, Tao F, Xue G. Detection of Interchain Proximity and Segmental Motion of Polymer Glass. Macromolecules 2011. [DOI: 10.1021/ma200962c] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jie Xu
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Co-ordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Dawei Li
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Co-ordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Jiao Chen
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Co-ordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Lei Din
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Co-ordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Xiaoliang Wang
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Co-ordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Fangfang Tao
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Co-ordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Gi Xue
- Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Co-ordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China
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Affiliation(s)
- Hugues Bodiguel
- ESPCI CNRS Université Paris 6, Laboratoire de Physico-Chimie des Polymères et des Milieux Dispersés UMR 7615, 10 rue Vauquelin, F-75231 Paris Cedex 05, France
| | - Christian Fretigny
- ESPCI CNRS Université Paris 6, Laboratoire de Physico-Chimie des Polymères et des Milieux Dispersés UMR 7615, 10 rue Vauquelin, F-75231 Paris Cedex 05, France
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16
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Fujii Y, Akabori KI, Tanaka K, Nagamura T. Chain Conformation Effects on Molecular Motions at the Surface of Poly(methyl methacrylate) Films. Polym J 2007. [DOI: 10.1295/polymj.pj2006270] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Capaccioli S, Ngai KL, Shinyashiki N. The Johari-Goldstein beta-relaxation of water. J Phys Chem B 2007; 111:8197-209. [PMID: 17585798 DOI: 10.1021/jp071857m] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
There is a plethora of experimental data on the dynamics of water in mixtures with glycerol, ethylene glycol, ethylene glycol oligomers, poly(ethylene glycol) 400 and 600, propanol, poly(vinyl pyrrolidone), poly(vinyl methylether), and other substances. In spite of the differences in the water contents, the chemical compositions, and the glass transition temperatures Tg of these aqueous mixtures, a faster relaxation originating from the water (called the nu-process) is omnipresent, sharing the following common properties. The relaxation time tau(nu) has Arrhenius temperature dependence at temperatures below Tg of the mixture. The activation energies of tau(nu) all fall within a neighborhood of 50 kJ/mol. At the same temperature where mixtures are all in their glassy states, the values of tau(nu) of several mixtures are comparable. The Arrhenius temperature dependence of tau(nu) does not continue to higher temperatures and instead it crosses over to a stronger temperature dependence at temperatures above Tg. The dielectric relaxation strength of the nu-process, Deltaepsilon(nu)(T), has a stronger temperature dependence above Tg than below, mimicking the change of enthalpy, entropy, and volume when crossing Tg. These general property of the nu-process (except for the magnitude of the activation energy) had been found before in the secondary relaxation of the faster component in several binary nonaqueous mixtures. Other properties of the secondary relaxation in these nonaqueous mixtures have helped to identify it as the Johari-Goldstein (JG) secondary relaxation of the faster component. The similarities in properties lead us to conclude that the nu-processes in water mixtures are the JG secondary relaxations of water. The conclusion is reinforced by the processes behaving similarly to the nu-process found in 6 A thick water layer (two molecular layers) in fully hydrated Na-vermiculite clay, and in water confined in molecular sieves, silica hydrogels, and poly(2-hydroxyethyl methacrylate) hydrogels.
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Affiliation(s)
- S Capaccioli
- Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa, Italy
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18
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Bodiguel H, Fretigny C. Reduced viscosity in thin polymer films. PHYSICAL REVIEW LETTERS 2006; 97:266105. [PMID: 17280434 DOI: 10.1103/physrevlett.97.266105] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Indexed: 05/13/2023]
Abstract
The dewetting of thin polystyrene films (20-500 nm) on a liquid substrate is studied at time scales that are long compared to the reptation time. It is shown that the kinetics correspond to those of purely viscous flow and that the viscosity measured by this technique is, for the thickest films, consistent with bulk measurements. Films on the order of the coil size are then studied. The effective viscosity of these films displays a large decrease when the film thickness h is below several radius of gyration, R(g). This viscosity reduction is found to depend only on the ratio h/R(g).
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Affiliation(s)
- Hugues Bodiguel
- Laboratoire PPMD, CNRS UMR 7615, ESPCI, 10 rue Vauquelin, 75235 Paris Cedex 05, France
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19
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Erdem ÖF, Michel D. Molecular dynamics of ethylene glycol adsorbed in NaX: NMR and broadband dielectric spectroscopy studies. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.10.110] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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20
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Ngai K. Interpreting the dynamics of nano-confined glass-formers and thin polymer films: Importance of starting from a viable theory for the bulk. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.20923] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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21
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Oyerokun FT, Schweizer KS. Theory of glassy dynamics in conformationally anisotropic polymer systems. J Chem Phys 2005; 123:224901. [PMID: 16375504 DOI: 10.1063/1.2135776] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A mode coupling theory for the ideal glass transition temperature, or crossover temperature to highly activated dynamics in the deeply supercooled regime, T(c), has been developed for anisotropic polymer liquids. A generalization of a simplified mode coupling approach at the coarse-grained segment level is employed which utilizes structural and thermodynamic information from the anisotropic polymer reference interaction site model theory. Conformational alignment or/and coil deformation modifies equilibrium properties and constraining interchain forces thereby inducing anisotropic segmental dynamics. For liquid-crystalline polymers a small suppression of T(c) with increasing nematic or discotic orientational order is predicted. The underlying mechanism is reduction of the degree of coil interpenetration and intermolecular repulsive contacts due to segmental alignment. For rubber networks chain deformation results in an enhanced bulk modulus and a modest elevation of T(c) is predicted. The theory can also be qualitatively applied to systems that undergo nonuniversal local deformation and alignment, such as polymer thin films and grafted brush layers, and large elevations or depressions of T(c) are possible. Extension to treat directionally dependent collective barrier formation and activated hopping is possible.
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Affiliation(s)
- Folusho T Oyerokun
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
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22
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Akabori KI, Tanaka K, Nagamura T, Takahara A, Kajiyama T. Molecular Motion in Ultrathin Polystyrene Films: Dynamic Mechanical Analysis of Surface and Interfacial Effects. Macromolecules 2005. [DOI: 10.1021/ma051143e] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kei-ichi Akabori
- Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Keiji Tanaka
- Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Toshihiko Nagamura
- Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Atsushi Takahara
- Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Tisato Kajiyama
- Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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Inoue R, Kanaya T, Nishida K, Tsukushi I, Shibata K. Inelastic neutron scattering study of low energy excitations in polymer thin films. PHYSICAL REVIEW LETTERS 2005; 95:056102. [PMID: 16090891 DOI: 10.1103/physrevlett.95.056102] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2005] [Indexed: 05/03/2023]
Abstract
We report inelastic neutron scattering measurements on polystyrene thin films in a glassy state in the meV region. We found in elastic scattering that the mean square displacement <u2> decreased with film thickness, and hence the corresponding force constant f increased. In inelastic and quasielastic scattering, we observed the so-called boson peak at around 1.5 meV and the picosecond fast process for the first time in thin films, both of which decreased in intensity with film thickness. These results were discussed in terms of the potential hardening due to the confinement of polymer chains and/or the interfacial dead layer.
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Affiliation(s)
- Rintaro Inoue
- Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan
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Beltrán CM, Langevin D. Stratification kinetics of polyelectrolyte solutions confined in thin films. PHYSICAL REVIEW LETTERS 2005; 94:217803. [PMID: 16090351 DOI: 10.1103/physrevlett.94.217803] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Indexed: 05/03/2023]
Abstract
We have studied free horizontal liquid films made with semidilute polyelectrolyte solutions. A stratification phenomenon is observed during film thinning, with a step size close to the mesh size of the polymer network: dark domains nucleate and expand, the outer polymer layer dewetting a thinner film. The kinetics of dark spot expansion is not simply related to bulk viscosity and becomes faster when the film thickness decreases, suggesting an increase of the chain mobility of the confined polymer chains. These findings are similar to recent ones for other confined liquids and are the first reported so far for freely standing films.
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Affiliation(s)
- César Márquez Beltrán
- Laboratoire de Physique des Solides, Bâtiment 510, Université Paris-Sud, 91405 Orsay Cedex, France
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Kalogeras IM, Neagu ER. Interplay of surface and confinement effects on the molecular relaxation dynamics of nanoconfined poly(methyl methacrylate) chains. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2004; 14:193-204. [PMID: 15254839 DOI: 10.1140/epje/i2004-10015-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The thermally stimulated current (TSC) signatures of the primary (alpha) transition and its precursor, the Johary-Goldstein (beta) relaxation, are used to probe effects of nanoconfinement on the dielectric relaxation dynamics of poly(methyl methacrylate) (PMMA) radically polymerised in situ 50 angstroms mean pore size silica-gel. Nanoconfinement leads to a broadened and low-temperature-shifted beta band (peaking at Tbeta, with deltaTbeta = T(conf.)beta - T(bulk)beta = -15 degrees C for a heating rate of 5 deg/min), signifying the occurrence of faster relaxing moieties compared to the bulk-like PMMA film. Furthermore, both TSCs and differential scanning calorimetry (DSC) estimate a rise of the glass transition temperature for the confined phase ([Formula: see text]= +13 degrees C) and an increased width for the corresponding transition signals, relative to the signals in the bulk. Simple free-volume and entropy models seem inadequate to provide a collective description of the above perturbations. The observation of a spatial heterogeneity regarding the relaxation dynamics is discussed in terms of the presence of a motional gradient, with less mobile segments near the interface and more mobile segments in the core, and the interplay of adsorption ( e.g., strong physical interactions that slow down molecular mobilities) and confinement effects ( e.g., lower entanglements concentration and local density fluctuations that provide regions of increased free space). The results suggest that in the case of high-molecular-weight polymers confined in small-pore systems, adsorption effects have considerable bearing on the glass transition phenomenon whereas confinement primarily influences side-chains' rotational mobilities. The confinement effect is expected to dominate over adsorption for PMMA phases occluded in higher pore sizes and silanised walls.
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Affiliation(s)
- I M Kalogeras
- Department of Physics, Section of Solid State Physics, University of Athens, Panepistimiopolis, 157 84, Zografos, Greece.
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