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arXiv · 2402.11210

Surface mobility gradient and emergent facilitation in glassy films

Qiang Zhai·Xin-Yuan Gao·Chun-Shing Lee·Chin-Yuan Ong·Ke Yan·Hai-Yao Deng·Sen Yang·Chi-Hang Lam
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Abstract

Confining glassy polymer into films can substantially modify their local and film-averaged properties. We present a lattice model of film geometry with void-mediated facilitation behaviors but free from any elasticity effect. We analyze the spatially varying viscosity to delineate the transport property of glassy films. The film mobility measurements reported by [Yang et. al., Science, 2010, 328, 1676] are successfully reproduced. The flow exhibits a crossover from simple viscous flow to a surface-dominated regime as temperature decreases. The propagation of a highly mobile front induced by the free surface is visualized in real space. Our approach provides a microscopic treatment of the observed glassy phenomena.

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Qiang Zhai, Xin-Yuan Gao, Chun-Shing Lee, Chin-Yuan Ong, Ke Yan, Hai-Yao Deng, Sen Yang, Chi-Hang Lam. 2024-02-17. Surface mobility gradient and emergent facilitation in glassy films. https://doi.org/10.1039/d4sm00221k

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