高压流体界面受限扩散调控多孔聚合物薄膜孔结构的机制研究

Porous polymer films have the "from surface to inside" open cell structure, and it can be used in many applications such as separation, fractionation, loading, and so on. However, lots of organic solvents are usually involved during the preparation process. High-pressure fluids have been verified as a green method to generate bubbles in polymer matrixes. Unfortunately, the high-pressure fluids have high diffusivity, and it is a challenge to fabricate the desired porous polymer films with thickness less than 50 micron and with the open cell structure "from surface to inside" using the physical foaming method. Recently, in our preliminary study, a novel strategy of "the restricted high-pressure fluid diffusion at interface" have been carried out to solve this challenge, and some exciting experimental results have been achieved. In this project, we are going to select several typical polymer films or films with various diffusivities as the foaming systems and the flexible diffusion barrier layers, to fabricate a series of porous polymer films after films assembling and then the physical foaming. This project will investigate the evolution of cell structure and critical parameters of polymer films foaming under the fluid-diffusion-restricted situation, and the properties of the obtained porous polymer films. Meanwhile, via an in-situ visualization system, the cell nucleation, growth, cell-opening mechanisms will be discussed. The current study could be helpful to promote the usage of the physical pore forming method in porous polymer film fields.

多孔聚合物薄膜具有“由表至里”的开孔结构可应用于分级分离、负载等重要领域，但其致孔过程中常使用大量有机溶剂。高压流体物理发泡是制备多孔聚合物的重要方法且绿色环保，不过高压流体扩散速率大，在制备厚度小于50微米且具有“由表至里”开孔结构的多孔聚合物薄膜方面存在技术挑战。在前期的探索研究中，申请人从“高压流体界面受限扩散”着手来解决上述瓶颈问题，获得了振奋人心的实验结果。本研究拟在此基础上，选择具有不同高压流体扩散系数的典型聚合物薄膜发泡体系和柔性扩散阻隔膜体系，经结构组装、物理发泡制备一系列厚度为10-100微米且具有“由表至里”开孔结构的多孔聚合物薄膜，研究聚合物薄膜在柔性扩散受限环境下的孔结构演变规律、重要控制参数以及材料性能，同时借助具有静态和拉伸模式的可视化发泡系统，深入理解聚合物薄膜的泡孔成核、增长以及开孔机制，为高压流体发泡致孔法在多孔聚合物薄膜领域的应用进行有益探索。

多孔聚合物薄膜具有“由表至里”的开孔结构，但制备过程常使用大量有机溶剂。高压流体物理发泡是制备多孔聚合物的重要方法且绿色环保，但高压流体的扩散速率大，在制备多孔聚合物薄膜方面存在技术挑战。本项目从“高压流体界面受限扩散”着手，通过复合气体阻隔膜、涂覆PVA阻隔层、发泡剂复用、解吸附环境控制等手段来控制高压流体发泡剂的解吸附行为，经间歇发泡技术，制备了多种多孔聚合物薄膜、片材、珠粒、异型材等，系统研究了多孔聚合物在扩散受限环境下的泡孔结构演变规律、重要控制参数和材料性能，阐明了界面成核行为和成核气核在扩散受限环境下的增长行为，揭示了物理发泡多孔聚合物薄膜表面开孔的机制和取向泡孔形成的机制。项目执行过程中成功开发了聚合物发泡卷材半连续加工技术，实现了大幅宽热塑弹性体发泡卷材的制备和技术转移转化。