Modeling solvent evaporation during thin film formation in phase separating polymer mixtures
Modeling solvent evaporation during thin film formation in phase separating polymer mixtures
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DOI：
10.1039/c7sm02560b
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发表时间：
2018-03-14
期刊：
影响因子：
3.4
通讯作者：
Kumar, Rajeev
中科院分区：
文献类型：
--
作者：
Cummings, John;Lowengrub, John S.;Kumar, Rajeev
通过将聚合物溶解在普通溶剂中，然后蒸发该溶剂来制备薄膜已经成为一种常规的加工过程。然而，由于需要模拟多个长度和时间尺度的过程，对蒸发溶剂中的薄膜形成的建模一直是具有挑战性的。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学，它允许系统地研究各种影响，如从液体到蒸汽的相变引起的溶剂性质的变化，以及这种溶剂转变引起的聚合物热力学。该方法允许推导每个表面附近的蒸发通量和边界条件，以模拟接近平衡的系统。我们应用它来研究相分离聚合物共混物在普通挥发性溶剂中溶解并沉积在平面衬底上的薄膜微结构演变。研究了蒸发速率、聚合物与衬底的相互作用和浓度依赖的迁移率对薄膜形成动力学的影响。
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.