基于选择性溶胀成孔的聚砜基两亲嵌段共聚物分离膜

Microphase separation of block copolymers enables the fabrication of membranes with both high selectivity and high permeability, and is playing an increasingly important role in the membrane field. Unfortunately, only polystyrene-based block copolymers are involved in the current research and their poor mechanical robustness and difficulties in the large-scale synthesis prevent them from practical applications. Considering that i) polysulfone (PSF) exhibits excellent mechanical strength and chemical stability, and is one of the most popular polymers used to manufacture separation membranes; ii) polyethylene glycol (PEG) is a highly polar polymer, frequently used as additives to improve the hydrophilicity of membranes; iii) block copolymers of PSF and PEG can be easily synthesized, we propose a new idea to prepare membranes by selective swelling amphiphilic block copolymers of PSF and PEG (PSF-b-PEG). We will design and synthesize PSF-b-PEG copolymers with PSF as the majority blocks, and prepare their continuous films by melting processing through a twin screw extruder. The films will be soaked in selective solvents to expand the PEG microdomains and form pores after drying, thus obtaining membranes with PSF as the robust framework and PEG chains lined along the pore walls. We will also investigate the hydration of PEG layers along membrane pores and its influence on the separation properties. This project aims to reveal the microphase separation behavior of amphiphilic polysulfone block copolymers as well as their interactions with selective solvents. Eventually, we expect to establish a new methodology to producing advanced membranes of block copolymers with high selectivity, strong mechanical robustness, and intrinsic permanent hydrophilicity, and thus contributing to the large-scale production and real-world applications of block copolymer membranes.

嵌段共聚物微相分离是制备高选择性、高渗透性分离膜的独特方法，近年来备受关注。但由于缺乏高强度、成本可接受的共聚物，嵌段共聚物膜尚不能工业化。本项目突破当前的研究集中于低强度、高成本聚苯乙烯基嵌段共聚物的局限，提出将高强度的聚砜与强极性的聚乙二醇进行嵌段共聚，再通过选择性溶胀成膜的新思路。将设计、合成聚砜为主体相的两亲嵌段共聚物，通过熔融挤出加工制备连续薄膜，并用极性溶剂诱发聚乙二醇微区发生选择性溶胀，产生孔道，获得聚砜为主体结构、聚乙二醇富集于孔壁的嵌段共聚物分离膜。分离膜将具有高强度、高选择性和自发永久亲水的特性。将研究聚砜分子链的高刚性和聚乙二醇的结晶特性对共聚物的分相和溶胀行过程的影响、聚乙二醇水化作用下的膜分离特性，并揭示受限条件下，共聚物的微相分离行为及嵌段与溶剂的相互作用规律，以建立“挤出成膜-选择性溶胀成孔”的嵌段共聚物膜的清洁制备方法，为其规模制备和实际应用奠定科学基础。

嵌段共聚物微相分离是制备高选择性、高渗透性分离膜的独特方法，近年来备受关注。但由于缺乏高强度、成本可接受的共聚物，嵌段共聚物膜尚不能工业化。本项目突破当前的研究集中于低强度、高成本聚苯乙烯基嵌段共聚物的局限，建立了高强度的聚砜基嵌段共聚物的合成方法。通过控制投料比调节两嵌段质量比，确定了适用于选择性溶胀成孔方法的聚砜/聚乙二醇嵌段共聚物（SFEG）原料的合成条件；通过放大研究，实现了SFEG嵌段共聚物公斤级原料的合成。揭示了不同溶剂与SFEG嵌段共聚物两相的相互作用，建立了选择性溶胀温度、溶胀时间、溶胀剂组成与膜孔径、表面亲水性、渗透分离之间的关系；进行了SFEG膜的放大制备研究，建立了“挤出成膜-选择性溶胀成孔”的嵌段共聚物膜的清洁制备方法，为其规模制备和实际应用奠定科学基础。研究了SFEG膜在水处理、纳米级物质筛分、血液透析、锂电池隔膜等领域的应用。