用正电子湮没研究高分子气体分离膜的微孔结构及其对气体分离的影响机制

气体膜分离技术在CO2捕获收集、H2回收、天然气净化等诸多领域都有广泛的应用。高分子膜是目前工业领域应用最广的气体分离膜。分离膜中的气体渗透率和选择性，是评价膜材料气体分离性能的主要指标，而这两个指标均与膜材料中亚纳米级的超微孔结构密切相关。然而，常规气体吸附无法准确测量这些与气体分子动力学直径相当的超微孔。本项目拟采用正电子湮没方法，系统研究高分子膜中的微孔结构对气体分离性能的影响，研究内容包括：1）发展和完善高分子气体分离膜中孔洞结构的正电子湮没表征手段，准确测量孔洞尺寸、相对浓度、连通性等；2）通过分子设计，或物理老化等手段，探索调控膜材料中微孔结构的手段，调节孔洞尺寸、相对孔隙率、孔洞连通性等；3）研究孔洞尺寸分布对膜材料气体选择性的影响，孔隙率以及孔洞连通性等对气体渗透率的影响。本项目研究成果将有助于深入理解气体在高分子膜中的扩散机制，为提高膜材料的气体分离性能提供理论指导。

Membrane gas separation has intensive applications in many fields, such as CO2 capture, H2 recovery, natural gas purification and so on. Polymeric separation membrane is the most widely used gas separation membrane in industry. The gas permeability and selectivity in separation membrane are the main parameters to evaluate the gas separation performance, which are closely related to the ultramicropore structure in the membrane materials. However, conventional nitrogen adsorption/desorption cannot accurately measure these ultramicropores with size close to the kinetic diameter of gas molecules. In this project, we will use positron annihilation spectroscopy to systematically study the influence of micropore structure on the gas separation performance of polymer membrane. The research contents include: 1) Develop the positron annihilation spectroscopy as a sensitive method for the characterization of pore structures in polymeric gas separation membrane. Accurately measure the pore size, relative pore concentration, pore connectivity, etc.; 2) Explore the means of regulating the micropore structure of membrane materials through molecular design or physical aging and other methods, to adjust the pore size, relative porosity, pore connectivity, etc.; 3) Study the role of pore size distribution on gas selectivity of membrane materials, and the influence of porosity and pore connectivity on gas permeability. The research results of this project will help to understand the diffusion mechanism of gas in polymer membrane and provide theoretical guidance for improving the gas separation performance of membrane materials.