Phan Anh D, Schweizer Kenneth S
Faculty of Materials Science and Engineering, Phenikaa Institute for Advanced Study, Phenikaa University, Hanoi 12116, Vietnam.
Faculty of Information Technology, Artificial Intelligence Laboratory, Phenikaa University, Hanoi 12116, Vietnam.
ACS Macro Lett. 2020 Apr 21;9(4):448-453. doi: 10.1021/acsmacrolett.0c00006. Epub 2020 Mar 13.
We employ a new force-level statistical mechanical theory to predict spatial gradients of the structural relaxation time and of polymer liquids near microscopically rough and smooth hard surfaces and contrast the results with vapor interface systems. Repulsive rough (smooth) surfaces induce large slowing down (modest speeding up) of the relaxation time compared to the bulk. Nevertheless, a remarkable degree of universality of distinctive dynamical behaviors is predicted for different polymer chemistries and all interfaces, including a double exponential form of the alpha time gradient, power law decoupling of the relaxation time from its bulk value with exponential spatial variation of the exponent, exponential spatial gradient of , weak dependence of normalized gradients on vitrification criterion, and near linear growth with cooling of the slowed down layer thickness near a rough hard interface. The results appear consistent with simulations and experiments, and multiple testable predictions are made.
我们采用一种新的力级统计力学理论来预测聚合物液体在微观粗糙和光滑硬表面附近的结构弛豫时间的空间梯度，并将结果与气相界面系统进行对比。与本体相比，排斥性粗糙（光滑）表面会导致弛豫时间大幅减慢（适度加快）。然而，预测表明，对于不同的聚合物化学组成和所有界面，独特的动力学行为具有显著的普遍性，包括α时间梯度的双指数形式、弛豫时间与其本体值的幂律解耦以及指数的指数空间变化、的指数空间梯度、归一化梯度对玻璃化标准的弱依赖性，以及在粗糙硬界面附近减慢层厚度随冷却的近似线性增长。结果似乎与模拟和实验一致，并做出了多个可测试的预测。
