Correspondence between the rigid amorphous fraction and nanoconfinement effects on glass formation. Issue 12 (15th March 2017)

• Record Type: Journal Article
• Authors: Lee, Jonathan; Mangalara, Jayachandra Hari; Simmons, David S.
• Is Part Of: Journal of polymer science. Volume 55:Issue 12(2017)
• Page Start: 907
• Page End: 918
• Publication Date: 2017-03-15
• Subjects: glass transition -- nanoconfinement effects -- rigid amorphous fraction -- semicrystallinity -- thin films; 547
• DOI: 10.1002/polb.24324
• Languages: English
• ISSNs: 0887-6266

Abstract

ABSTRACT: Semicrystalline polymers' properties are strongly influenced by the presence of a "rigid amorphous fraction" (RAF) of material with enhanced glass transition temperature and suppressed mobility. Here, we review striking similarities between this domain and near‐interface regions of altered dynamics in other nanostructured polymers, including thin films, nanocomposites, layered films, and ionomers. Building on these observations, we present results of molecular simulations of model nanolayered polymers in which one layer is crystalline. The results of these simulations, which bear close similarities to semicrystalline homopolymers while providing a well‐defined equilibrium crystal size, suggest that the RAF shares the same phenomenology and mechanism as dynamic interphases in these other polymeric systems. Specifically, the fraction of rigid amorphous material is driven by the scale of cooperative rearrangements characteristic of dynamics in polymers and other supercooled liquids. These results situate the RAF as a specific instance of a general tendency towards broad dynamic interphases in polymers and other glass‐forming materials. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2017, 55, 907–918 Abstract : The rigid amorphous fraction plays a central role in semicrystalline polymers' thermal, mechanical, and transport behaviors. Here, molecular dynamics simulations of semicrystalline nanolayered polymers indicate that the rigid amorphous fraction is driven by the same physics leading to the emergence of broad dynamic interphases in polymer films, nanolayers, nanocomposites, and ionomers.