两亲性聚砜嵌段共聚物的分子设计、形态控制及其在纳滤膜中的应用

Tailoring of amphiphilic block copolymers with novel architectures and controlling the corresponding self-assembly morphologies are very important topics in the field of polymer materials. However, the amphiphilic polysulfone block copolymers are difficult to synthesize due to the chemical inertia of polysulfone, which heavily limits their investigation and application. In our early study, amphiphilic polysulfone-block-polyethylene glycol block copolymer was synthesized through copolycondensation with end group functionalized polysulfone and polyethylene glycol monomethyl ether. The prepared block copolymer exhibited self-assembly behavior upon the thermal and solvent annealing treatments. In this project, living polysulfone is synthesized by polycondensation and nucleophilic substitution. In second step, the living polysulfone chains are extended with hydrophilic monomers using atom transfer radical polymerization (ATRP). A series of amphiphilic hydrophilic-containing polysulfone block copolymers with different chain lengths are prepared. The hydrophilic-containing polysulfone block copolymer membranes with uniform, hydrophilic and porous morphology are fabricated and tailored through the combining of non-solvent-induced phase separation (NIPS) and self-assembly technologies. Then thin film composite nanofiltration membrane (TFC NF) with high-performance is fabricated through direct interfacial polymerization to generate ultrathin the polyamide selective layer on the tailored block copolymer membrane surface. This study is revealing the influences of molecular design of amphiphilic polysulfone-based block copolymers and their surface morphology and property on the interfacial polymerization and the property of TFC NF, driving the development of safe drinking water treatment.

新型两亲性嵌段共聚物的分子设计及其自组装形态控制是当前高分子材料领域的研究热点。聚砜分子链的化学惰性使得两亲性聚砜嵌段共聚物难以合成，材料的匮乏限制了两亲性聚砜嵌段共聚物的研究和应用。申请人在前期研究中将聚砜分子链端基功能化使其具备反应活性，与聚乙二醇单甲醚共缩聚成功制备了两亲性聚砜嵌段共聚物，溶剂热处理表明该嵌段共聚物具有良好的自组装能力。本课题拟在反应性聚砜材料的基础上，利用活性聚合（ATRP）将亲水性链段以嵌段的方式引入聚砜分子链，通过优化聚合条件和使用不同种类的亲水链段，构建一系列结构可控的两亲性聚砜嵌段共聚物；利用自组装和相转化技术制备并调控聚砜嵌段共聚物基膜形态结构，在其上界面聚合形成超薄聚酰胺截留层，提升复合纳滤膜的综合性能；探究两亲性聚砜嵌段共聚物分子结构和表面形态与性质对界面聚合和纳滤膜性能的影响机制，助推我国饮用水安全领域的发展。

聚砜是目前主要的超滤膜材料，其化学惰性尽管有利于提高分离稳定性，但也限制了聚砜材料的改性。申请人通过分子设计，在聚砜分子链末端引入反应性基团制备反应性聚砜，利用亲核取代、ATRP等反应将亲水链段引入聚砜分子链中，构建一系列两亲性聚砜嵌段共聚物，并通过相转化法制备分离膜，利用溶剂热诱导相分离实现亲水链段在膜表面富集，调控聚砜嵌段共聚物膜的形态结构和性质，更进一步调控其上界面聚合层的结构，制备超薄高离子选择性的复合超滤膜，提升复合纳滤膜的综合性能。其中，制备的复合纳滤膜优化结果为纯水通量19 L m-2 h-1 bar-1，二价盐MgSO4/一价盐NaCl的分离选择系数5.0，优于项目设定目标(纯水通量10 L m-2 h-1 bar-1和二价盐MgSO4/一价盐NaCl的分离选择系数4.0)。本项目在新型膜材料设计方面，通过设计聚砜大分子引发剂，选择合适的配体、催化剂、溶剂、聚合工艺和亲水性聚合物，合成了一系列两亲性聚砜嵌段共聚物。本项目在分离膜结构、界面和性质调控方面，通过溶剂热诱导嵌段共聚物相分离，实现嵌段共聚物分离膜表面孔径、亲水性和粗糙度的参数调控。本项目在新型复合纳滤膜设计方法，利用基膜性质调控，实现了聚酰胺截留层的结构调控。本项目在揭示两亲性聚砜嵌段共聚物结构和性质对分离膜性能的影响机制方面具有重要的理论和方法创新，将为高性能分离膜的设计和制备提供科学指导。