Fast Processing Affects the Relaxation of Polymers: The Slow Arrhenius Process Can Probe Stress at the Molecular Level

Thoms, Erik; Wang, Kai; Chandran, Sivasurender; Napolitano, Simone

doi:10.1021/acs.jpclett.4c00902

Cited by 4 publications

(2 citation statements)

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“…Chowdhury et al investigated the relaxation of recoiling stress below the glass transition temperature and identified that the activation energy associated with such relaxation is comparable to the β-relaxations, which do not involve main chain segmental relaxations. Later they discussed this with a similarity to SAP relaxation. ,, …”

Section: Characterization Methodologiesmentioning

confidence: 99%

“…The SAP peak from the dielectric measurements has been found not to merge with the α-peak, distinguishing SAP from other Arrhenius relaxation mechanisms like β- and γ-relaxations. However, the preparation conditions of the polymer films have been found to affect the intensity of the SAP peak . Comprehensive investigations on a large class of materials and processes are required to explore the SAP, which is likely the most probable sub- T g relaxation mode in PS.…”

Section: Relevant Aspects In Confined Glassy Polymer Filmsmentioning

confidence: 99%

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Advancements in Novel Mechano-Rheological Probes for Studying Glassy Dynamics in Nanoconfined Thin Polymer Films

Madhusudanan,

Chowdhury

2024

ACS Polym. Au

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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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Section: Characterization Methodologiesmentioning

confidence: 99%

Section: Relevant Aspects In Confined Glassy Polymer Filmsmentioning

confidence: 99%

Advancements in Novel Mechano-Rheological Probes for Studying Glassy Dynamics in Nanoconfined Thin Polymer Films

Madhusudanan,

Chowdhury

2024

ACS Polym. Au

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Relaxation and entropy generation in dewetting thin glassy polymer films trapped far from equilibrium

Madhusudanan,

Chowdhury

2024

Journal of Polymer Science

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Polymers when confined to a dimension comparable to the length scale of polymer chain coils such as thin films, often lead to molecular relaxation processes distinct from their bulk counterpart. Often observed as thermal and mechanical responses such relaxation has been frequently associated with the squeezing of polymer chains having conformations trapped far from thermodynamic equilibrium and subsequently generating processing‐induced molecular recoiling stress. Relaxation in polymer films can be modified by tuning the molecular recoiling stress, which is directly influenced by the preparation conditions of the polymer thin films. Hence a comprehensive understanding of the genesis and relaxation of molecular recoiling stress becomes necessary. Here, we provide insights into the nonequilibrium nature observed in polymer thin films, focusing majorly on the investigations into the molecular recoiling stress using the dewetting technique. The impact of various factors like temperature of dewetting, thickness of films, molecular weight of polymers, and physical aging affecting the relaxation of molecular recoiling stress is discussed. In addition, discussions on the possible mechanisms of relaxation and modification of molecular recoiling stress by varying the spin‐coating speed and addition of plasticizers are also provided. An alternate approach which gives a new perspective into the relaxation of molecular recoiling stress considering the entropy generated during the dewetting of polymer films is also included. The present work is expected to give the reader a comprehensive understanding of the characteristics of molecular recoiling stress relaxation occurring in polymer thin films.

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Correlated Molecular Motion during Release of Residual Stress in Polymer Glassy Films

Ju,

Cheng,

Jiang

et al. 2024

J. Phys. Chem. B

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Fast Processing Affects the Relaxation of Polymers: The Slow Arrhenius Process Can Probe Stress at the Molecular Level

Cited by 4 publications

References 50 publications

Advancements in Novel Mechano-Rheological Probes for Studying Glassy Dynamics in Nanoconfined Thin Polymer Films

Advancements in Novel Mechano-Rheological Probes for Studying Glassy Dynamics in Nanoconfined Thin Polymer Films

Relaxation and entropy generation in dewetting thin glassy polymer films trapped far from equilibrium

Correlated Molecular Motion during Release of Residual Stress in Polymer Glassy Films

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