Department of Mathematics, The University of Tennessee, Knoxville, TN-37996, USA.
Soft Matter. 2018 Mar 7;14(10):1833-1846. doi: 10.1039/c7sm02560b.
Preparation of thin films by dissolving polymers in a common solvent followed by evaporation of the solvent has become a routine processing procedure. However, modeling of thin film formation in an evaporating solvent has been challenging due to a need to simulate processes at multiple length and time scales. In this work, we present a methodology based on the principles of linear non-equilibrium thermodynamics, which allows systematic study of various effects such as the changes in the solvent properties due to phase transformation from liquid to vapor and polymer thermodynamics resulting from such solvent transformations. The methodology allows for the derivation of evaporative flux and boundary conditions near each surface for simulations of systems close to the equilibrium. We apply it to study thin film microstructural evolution in phase segregating polymer blends dissolved in a common volatile solvent and deposited on a planar substrate. Effects of the evaporation rates, interactions of the polymers with the underlying substrate and concentration dependent mobilities on the kinetics of thin film formation are studied.
通过将聚合物溶解在常见溶剂中然后蒸发溶剂来制备薄膜已成为常规的处理程序。然而，由于需要模拟多个长度和时间尺度的过程，因此蒸发溶剂中的薄膜形成的建模一直具有挑战性。在这项工作中，我们提出了一种基于线性非平衡热力学原理的方法，该方法允许系统地研究各种效应，例如由于从液相到气相的相变导致溶剂性质的变化以及由于这种溶剂变化引起的聚合物热力学。该方法允许为接近平衡的系统模拟推导每个表面附近的蒸发通量和边界条件。我们将其应用于研究溶解在常见挥发性溶剂中的相分离聚合物共混物在平面衬底上沉积时的薄膜微观结构演化。研究了蒸发速率，聚合物与基底的相互作用以及浓度依赖性迁移率对薄膜形成动力学的影响。
