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Madhusudanan M, Chowdhury M. Advancements in Novel Mechano-Rheological Probes for Studying Glassy Dynamics in Nanoconfined Thin Polymer Films. ACS POLYMERS AU 2024; 4:342-391. [PMID: 39399890 PMCID: PMC11468511 DOI: 10.1021/acspolymersau.4c00022] [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: 03/15/2024] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 10/15/2024]
Abstract
The nanoconfinement effects of glassy polymer thin films on their thermal and mechanical properties have been investigated thoroughly, especially with an emphasis on its altered glass transition behavior compared to bulk polymer, which has been known for almost three decades. While research in this direction is still evolving, reaching new heights to unravel the underlying physics of phenomena observed in confined thin polymer films, we have a much clearer picture now. This, in turn, has promoted their application in miniaturized and functional applications. To extract the full potential of such confined films, starting from their fabrication, function, and various applications, we must realize the necessity to have an understanding and availability of robust characterization protocols that specifically target thin film thermo-mechanical stability. Being nanometer-sized in thickness, often atop a solid substrate, direct mechanical testing on such films becomes extremely challenging and often encounters serious complexity from the dominating effect of the substrate. In this review, we have compiled together a few important novel and promising techniques for mechano-rheological characterization of glassy polymer thin films. The conceptual background involved in each technique, constitutive equations, methodology, and current status of research are touched upon following a pedagogical tutorial approach. Further, we discussed each technique's success and limitations, carefully covering the puzzling or contradicting observations reported within the broad nexus of glass transition temperature-viscosity-modulus-molecular mobility (including diffusion and relaxation).
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Affiliation(s)
- Mithun Madhusudanan
- Metallurgical
Engineering and Materials Science, Indian
Institute of Technology Bombay, Mumbai 400076, India
| | - Mithun Chowdhury
- Metallurgical
Engineering and Materials Science, Indian
Institute of Technology Bombay, Mumbai 400076, India
- Center
for Research in Nano Technology and Science, Indian Institute of Technology Bombay, Mumbai 400076, India
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Madhusudanan M, Chowdhury M. An entropy generation approach to the molecular recoiling stress relaxation in thin nonequilibrated polymer films. J Chem Phys 2024; 160:014904. [PMID: 38180259 DOI: 10.1063/5.0185728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 12/18/2023] [Indexed: 01/06/2024] Open
Abstract
In polymers, the equilibrium state is achieved when the chains have access to the maximum number of conformational states, which allows them to explore a larger conformational space, leading to an increase in the entropy of the system. Preparation of thin polymer films using the spin-coating technique results in polymer chains being locked in a nonequilibrium state with lower entropy due to possible stretching of chains during the process. Allowing enough time for recovery results in the relaxation of the spin-coating-induced molecular recoiling stress. Annealing such a film generates entropy due to its inherent irreversibility. We employed the dewetting technique to determine the molecular recoiling stress relaxation time in poly-(tertbutyl styrene) thin films. Furthermore, we qualitatively differentiated the metastable states achieved by the polymer film using entropy generation in a relaxing polymer film as an effect of thermal entropy and associated it with the conformational entropy of polymer chains utilizing the molecular recoiling stress relaxation time. This enabled us to explain molecular recoiling stress relaxation using a rather simplistic approach involving segmental level molecular rearrangements in polymer chains by attaining transient metastable states through an entropically activated process driving toward equilibrium.
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Affiliation(s)
- Mithun Madhusudanan
- Lab of Soft Interfaces, Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Mithun Chowdhury
- Lab of Soft Interfaces, Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076, India
- Center for Research in Nano Technology and Science, Indian Institute of Technology Bombay, Mumbai 400076, India
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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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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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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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Relaxation behavior of polymer thin films: Effects of free surface, buried interface, and geometrical confinement. Prog Polym Sci 2021. [DOI: 10.1016/j.progpolymsci.2021.101431] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Fan X, Xu J, Chen L, Hong N, Wang C, Ma J, Ma Y. Processing Induced Nonequilibrium Behavior of Polyvinylpyrrolidone Nanofilms Revealed by Dewetting. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15430-15441. [PMID: 33306375 DOI: 10.1021/acs.langmuir.0c03098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Polyvinylpyrrolidone (PVP) nanofilms prepared by spin-coating have vast applications in biological and microdevice fields. However, detailed knowledge of processing induced nonequilibrium behavior of PVP nanofilms and solutions for minimizing residual stresses toward high-quality films has still been lacking. In the present study, we first explored the rapid film formation process via statistics on nascent holes. Next, by employing dewetting as a major probe, we revealed that many processing conditions, particularly previously overlooked variables like the atmosphere, substrates, and immersion time, were correlated substantially with the degree of nonequilibrium of nanofilms. Proper aging temperature and time were demonstrated essential for releasing residual stresses and achieving more equilibrium nanofilms. This work offered abundant experimental evidence in the building relationship between the processing and nonequilibrium nature of polymer nanofilms, which were crucial for their preparation and application.
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Affiliation(s)
- Xiao Fan
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China
| | - Jiao Xu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China
| | - Long Chen
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China
| | - Ning Hong
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China
| | - Chuanbo Wang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China
| | - Jinghong Ma
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China
| | - Yu Ma
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, P. R. China
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Mulama AA, Chandran S, Roumpos K, Oduor AO, Reiter G. Dewetting Rheology for Determining Viscoelastic Properties of Nonequilibrated Thin Polymer Films. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01384] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Austine A. Mulama
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
- Department of Physics and Materials Science, School of Biological and Physical Sciences, Maseno University, PO Box 333-40105, Maseno, Kenya
| | - Sivasurender Chandran
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
| | - Konstantinos Roumpos
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
| | - Andrew O. Oduor
- Department of Physics and Materials Science, School of Biological and Physical Sciences, Maseno University, PO Box 333-40105, Maseno, Kenya
| | - Günter Reiter
- Physikalisches Institut, Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg 79104, Germany
- Freiburg Center for Interactive Materials and Bio-inspired Technologies (FIT), Albert-Ludwigs-Universität, Freiburg 79110, Germany
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Chandran S, Baschnagel J, Cangialosi D, Fukao K, Glynos E, Janssen LMC, Müller M, Muthukumar M, Steiner U, Xu J, Napolitano S, Reiter G. Processing Pathways Decide Polymer Properties at the Molecular Level. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01195] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - Jörg Baschnagel
- Institut Charles Sadron, Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Cedex, Strasbourg, France
| | - Daniele Cangialosi
- Centro de Física de Materiales CFM (CSIC-UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 San Sebastin, Spain
| | - Koji Fukao
- Department of Physics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Emmanouil Glynos
- Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P.O.
Box 1385, 711 10 Heraklion, Crete, Greece
| | - Liesbeth M. C. Janssen
- Theory of Polymers and Soft Matter, Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands
| | - Marcus Müller
- Institute for Theoretical Physics, Georg-August-Universität, Göttingen, Germany
| | - Murugappan Muthukumar
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Ullrich Steiner
- Adolphe Merkle Institute, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
| | - Jun Xu
- Advanced Materials Laboratory of Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Simone Napolitano
- Laboratory of Polymer and Soft Matter Dynamics, Experimental Soft Matter and Thermal Physics, Faculté des Sciences, Université libre de Bruxelles (ULB), CP223, Boulevard du Triomphe, Bruxelles 1050, Belgium
| | - Günter Reiter
- Institute of Physics, University of Freiburg, Freiburg 79104, Germany
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Chandran S, Reiter G. Segmental Rearrangements Relax Stresses in Nonequilibrated Polymer Films. ACS Macro Lett 2019; 8:646-650. [PMID: 35619518 DOI: 10.1021/acsmacrolett.9b00116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We probed the relaxation of preparation-induced residual stresses in nonequilibrated polymer films through dewetting experiments. While we observed fast relaxations at temperatures close to or below the glass transition, at elevated temperatures these relaxation times were orders of magnitude longer than the reptation time. Intriguingly, applying appropriate scaling of preparation conditions allowed us to present all relaxation times, including published data, from various complementary experiments on a single master curve exhibiting an Arrhenius-type behavior. The corresponding activation energy (75 ± 10 kJ/mol) is similar to values obtained for the relaxation of segments in polystyrene. The observed long relaxation times suggest that residual stresses, a consequence of nonequilibrium conformations inherited from preparation, relax via concerted rearrangements of many segments.
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Affiliation(s)
- Sivasurender Chandran
- Institute of Physics, University of Freiburg, Herman Herder Str. 3, Freiburg, 79104, Germany
| | - Günter Reiter
- Institute of Physics, University of Freiburg, Herman Herder Str. 3, Freiburg, 79104, Germany
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A ND, Begam N, Ibrahim M, Chandran S, Padmanabhan V, Sprung M, Basu JK. Viscosity and fragility of confined polymer nanocomposites: a tale of two interfaces. NANOSCALE 2019; 11:8546-8553. [PMID: 30990482 DOI: 10.1039/c8nr10362c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Viscosity and fragility are key parameters determining the processability and thermo-mechanical stability of glassy polymers and polymer nanocomposites (PNCs). In confined polymers, these parameters are largely dominated by the long relaxation times of the polymers adsorbed at the substrate-polymer interface. On the other hand, for polymer nanocomposites, the interface layer (IL) between the nanoparticles and the surrounding matrix chains often control not only the morphology and dispersion but also various parameters like viscosity and glass transition temperature. Confined PNCs, hence, present a unique opportunity to study the interplay of these two independent interfacial effects. Here, we report the results of X-ray scattering based dynamics measurements of PNC thin films, with a two IL width, unraveling the subtle interplay of these two interfaces on the measured viscosity and fragility. Coupled with coarse-grained molecular dynamics (MD) simulations, our experimental results demonstrate that the viscosity of the PNC films increases with both the IL width and the thickness of the polymer layer adsorbed at the substrate interface. However, while both pristine PS and PNCs with a higher IL width become stronger glasses, as estimated by their fragility, the PNC with a lower IL width shows an increase in fragility with increasing confinement. Our results suggest a novel method to control thermo-mechanical properties and stability of PNC coatings by independently controlling the two interfacial effects in athermal glassy PNCs.
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Affiliation(s)
- Nimmi Das A
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
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Glass transition at the polystyrene/polyethylene glycol interface observed via contact angle measurements. Polym J 2019. [DOI: 10.1038/s41428-018-0163-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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