Wang Fei, Altschuh Patrick, Ratke Lorenz, Zhang Haodong, Selzer Michael, Nestler Britta
Institute of Applied Materials-Computational Materials Science, Karlsruhe Institute of Technology (KIT), Straße am Forum 7, 76131, Karlsruhe, Germany.
Institute of Digital Materials Science, Karlsruhe University of Applied Sciences, Moltkestraße 30, 76133, Karlsruhe, Germany.
Adv Mater. 2019 Jun;31(26):e1806733. doi: 10.1002/adma.201806733. Epub 2019 Mar 11.
Polymeric porous media (PPM) are widely used as advanced materials, such as sound dampening foams, lithium-ion batteries, stretchable sensors, and biofilters. The functionality, reliability, and durability of these materials have a strong dependence on the microstructural patterns of PPM. One underlying mechanism for the formation of porosity in PPM is phase separation, which engenders polymer-rich and polymer-poor (pore) phases. Herein, the phase separation in polymer solutions is discussed from two different aspects: diffusion and hydrodynamic effects. For phase separation governed by diffusion, two novel morphological transitions are reviewed: "cluster-to-percolation" and "percolation-to-droplets," which are attributed to an effect that the polymer-rich and the solvent-rich phases reach the equilibrium states asynchronously. In the case dictated by hydrodynamics, a deterministic nature for the microstructural evolution during phase separation is scrutinized. The deterministic nature is caused by an interfacial-tension-gradient (solutal Marangoni force), which can lead to directional movement of droplets as well as hydrodynamic instabilities during phase separation.
聚合物多孔介质（PPM）作为先进材料被广泛应用，如隔音泡沫、锂离子电池、可拉伸传感器和生物过滤器。这些材料的功能、可靠性和耐久性在很大程度上依赖于PPM的微观结构模式。PPM中孔隙形成的一个潜在机制是相分离，它产生富含聚合物和贫聚合物（孔隙）的相。在此，从两个不同方面讨论聚合物溶液中的相分离：扩散和流体动力学效应。对于由扩散控制的相分离，回顾了两种新颖的形态转变：“簇状到渗流”和“渗流到液滴”，这归因于富聚合物相和富溶剂相异步达到平衡状态的效应。在流体动力学主导的情况下，仔细研究了相分离过程中微观结构演变的确定性本质。这种确定性本质是由界面张力梯度（溶质马兰戈尼力）引起的，它可导致液滴在相分离过程中的定向移动以及流体动力学不稳定性。
