高界面相容性的NIMs/PEs纳滤膜自组装及超亲/超疏性智能转化行为

The uniform dispersion of inorganic nanoparticles in the polymer matrix as well as the controllable wetness of the surface have been the subjects of intense scientific inquiry on upper-bound limits of membranes performances with high pollution-resistant property. The interfacial compatibility of particles and polymer, as well as the composition and the microstructure of the membrane surface are the keys on the inquiry subjects. This project proposed a novel nanoscale ionic material (NIMs), with polymeric canopy bound to a well-defined nanoparticle core by an ionic bond, as building block to prepare the hierarchal hybrid nanofiltration membrane by self-assembly. The NIMs in this work exhibit liquid-like behavior in the absence of solvents which would achieve free compatibility between nanoparticles and polyelectrolyte (PEs). Moreover, it shows charged surface functionalized with ionic species so that the designing and tailor on the surface composition and microstructure can be realized by readily exchange of NIMs counter ions with other ions. Therefore, the nanofiltration membrane with high performance and switchable superhydrophilicity -to- superhydrophobicity could be obtained. The correlation rules between the microstructure parameters of the membrane surface and the self-cleaning performances would be illustrated by the behaviors of pollutants with different components on the membrane interface, such as adsorption, sedimentation and migration. This proposal would provide a reference and theoretical guidance to the nanofiltration membrane with high performance and self-cleaning property, as well as the long term running stability for aimly treatment of individual water.

无机纳米粒子在聚合物膜中的均匀分散以及杂化膜表面的润湿性调控，是突破聚合物膜分离性能"upper-bound"上限并具有高抗污染性所面临的共性科学问题。解决该问题的主要关键是纳米粒子与聚合物的界面相容性以及膜表面的组成和微结构设计。本项目以新型的具有有机冠状层结构的纳米尺度离子化材料(NIMs)组装基元自组装构筑高负载的阶层式杂化纳滤膜，不但可实现纳米粒子与聚电解质(PEs)的无缝相容，还可通过NIMs和PEs的反离子交换，在多尺度范围实现膜表面组成和微结构设计与剪裁，得到高分离性能且表面润湿性可调控的超亲/超疏性智能转换纳滤膜。通过对不同污染物组分在膜表面的吸附、沉积和迁移等界面行为考察，得到纳滤膜表面微纳结构参数与抗污染、自清洁性能之间的关联规律。为有目标性地针对不同处理水体设计和优化新型高抗污染和自清洁纳滤膜以及膜的长期稳定运行提供借鉴和理论指导。

膜表面润湿性调控对其分离性能的改善和提高具有重要的作用。本项目基于膜表面化学组成、荷电基团和微结构的调控，构筑了系列不同微结构、荷电性和润湿性的有机/无机复合纳滤膜，深入研究膜表面润湿性变化规律及其分离性能间的构效关系，探索了构筑智能转化型(超)亲水/(超)疏水性复合膜的有效途径，揭示了不同润湿性复合膜的稳定性和抗污染性机理，获得系列高分离性能且运行稳定性良好的(超)亲水/(超)疏水复合膜，可用于水溶液体系的纳滤分离，或者有机溶剂体系的有机溶剂纳滤分离。对水溶液中染料的截留率均高于95.87%，水通量达202.5 L/m2.MPa.h，对乙醇溶液中的染料的截留率可达98.9%，乙醇通量可达60.45 L/m2.MPa.h。以XDLVO理论分析了不同润湿性膜表面的界面作用力、范德华力、双电层力以及极性力对膜污染的贡献，解析了典型污染物在不同润湿性纳滤膜表面的污染机理，为通过不同润湿性调控得到高性能分离膜提供了有力支撑。