The performance and the application of membranes, which are usually produced from polymer solutions, are strongly determined by their porous microstructures. One important mechanism for producing the porous microstructures of membranes is polymerization-induced phase separation (PIPS). Here, we scrutinize PIPS by employing a Cahn–Hilliard–Navier–Stokes method coupling with the Flory–Huggins model. We focus on the formation of membranes via diffusion as well as capillary flow. We report several morphological evolution characteristics of PIPS: (1) an asynchronous effect, where the polymer-rich phase and the polymer-lean phase reach their equilibrium concentrations at different times, (2) a center-to-center movement and collision-induced collision of polymer-rich particles, (3) transition of network structures into polymer particles and rebuilding of network structures from polymer particles, (4) polymer ring patterns. We expect that these findings would shed light on complex microstructures of membranes and provide guidance for the fabrication of desired membranes.

通常由聚合物溶液制得的膜的性能和应用取决于其多孔的微观结构。产生膜的多孔微结构的一种重要机制是聚合诱导相分离（PIPS）。在这里，我们通过采用Flory-Huggins模型的Cahn-Hilliard-Navier-Stokes方法来检查PIPS。我们专注于通过扩散以及毛细流动形成膜。我们报告了P​​IPS的几种形态演化特征：（1）异步效应，其中富聚合物相和贫聚合物相在不同时间达到其平衡浓度，（2）中心到中心运动和碰撞诱导富含聚合物的粒子碰撞 （3）将网络结构转变为聚合物颗粒，并从聚合物颗粒重建网络结构，（4）聚合物环型。我们希望这些发现将为膜的复杂微观结构提供启示，并为所需膜的制造提供指导。