arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2212.04296cond-mat.mtrl-scicond-mat.softcond-mat.stat-mechphysics.class-ph
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自支撑polymer薄膜玻璃化转变中的桥假说

On the bridge hypothesis in the glass transition of freestanding polymer films

Haggai Bonneau, Maxence Arutkin, Rainni Chen, James A Forrest, Elie Raphael, Thomas Salez

摘要:

具有高分子量的自支撑薄聚合物膜表现出玻璃化转变温度随膜厚度的异常降低。具体来说,在此类材料中,测得的玻璃化转变温度随膜厚度以仿射方式变化,其斜率弱依赖于分子量。De Gennes提出了一种滑动机制作为这些系统中假设的主要松弛过程,其中应力扭结可以通过所谓的桥以类似于爬行的方式传播,即沿着聚合物大分子的主链从一个自由界面传播到另一个。在这里,通过考虑有限大小的随机游动在一个封闭的盒子里的确切统计,我们详细调查的桥梁假设。我们表明,滑动机制不能再现实验中出现的基本功能,我们展示了这样一个事实背后的根本原因。

英文摘要:

Freestanding thin polymer films with high molecular weights exhibit an anomalous decrease in the glass-transition temperature with film thickness. Specifically, in such materials, the measured glass-transition temperature evolves in an affine way with the film thickness, with a slope that weakly depends on the molecular weight. De Gennes proposed a sliding mechanism as the hypothetical dominant relaxation process in these systems, where stress kinks could propagate in a reptation-like fashion through so called bridges, i.e. from one free interface to the other along the backbones of polymer macromolecules. Here, by considering the exact statistics of finite-sized random walks within a confined box, we investigate in details the bridge hypothesis. We show that the sliding mechanism cannot reproduce the basic features appearing in the experiments, and we exhibit the fundamental reasons behind such a fact.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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