基于同质增强的聚氯乙烯中空纤维膜结构设计及界面微尺度梯度结构调控

Based on the principles of polymer processing, according to thermal dynamic theory and shear-core spinning principle of chemical fibers, using PVC polymer and homogenous-reinforced method, the composition of spinning dope (surface separation layer) and reinforced matrix structure (PVC hollow fiber porous matrix membrane) would be designed. The evolution mechanism of structure and the physical-chemical reaction between the surface separation layer and the reinforced matrix during the continuous spinning dope and reinforced matrix co-extrusion-interaction-coagulation processes would be clarified. The gradient microstructure interface was established by synergy micro-phase inversion, e. g. to produce the porous interface of reinforced hollow fiber via delay phase separation, to produce interpenetrating network bi-continuous gradient layer via hydrothermal composite phase separation, to produce dense and smooth outer surface via instantaneous phase separation, respectively. The gradient microstructure distribution was established from reinforced matrix to the outer surface. The amphiphilic membrane surfaces which gave the homogenous-reinforced PVC hollow fiber membrane the excellent antifouling properties would be constructed via surface segregation. Then the model of fouling mechanism was established in water treatment application. The scientific basis would be provided for development of high performance hollow fiber membranes having not only excellent mechanical properties but also high separation precision.

本课题从高分子加工原理出发，根据热力学相容性理论和化学纤维皮/芯复合纺丝原理，以聚氯乙烯为成膜聚合物，采用同质增强方式，设计铸膜液（表面分离层）组成和增强体（PVC中空纤维多孔基膜）结构，阐明连续铸膜液/增强体共挤出-复合-固化成形过程中表面分离层与增强体之间物理、化学作用和结构演变机制；基于协同微相分离构造具有梯度渐变结构的界面层，即通过延时相分离构造多孔界面，通过水热复合相分离构造互穿网络双连续结构渐变层，通过瞬时相分离构造较致密外表面，以建立从增强体到外表面多级微孔结构的梯度分布；利用表面偏析构筑两亲膜表面，赋予增强膜优异抗污染性能，建立膜污染机制模型。为规模开发面向水处理应用、兼具增强体优异力学性能和溶液相转化法高分离精度的高性能中空纤维膜提供科学依据。

本项目根据热力学相容性理论和化学纤维皮/芯复合纺丝原理，以熔融纺丝-在线拉伸技术所得聚氯乙烯(PVC)中空纤维多孔膜为增强体基膜，调置PVC铸膜液，采用干-湿法纺丝技术在多孔基膜表面复合表面分离层，制备兼具高强度和高分离精度的同质增强型PVC中空纤维膜，研究了铸膜液与基膜接触时间和溶剂/潜溶剂/非溶剂组成对同质增强型PVC中空纤维膜结构与性能的影响；以聚乙二醇甲基丙烯酸酯（PEGMA）为亲水性链段、甲基丙烯酸三氟乙酯（TFEMA）为低表面能链段，通过自由基聚合制备PVC-g-PPEGMA-g-PTFEMA接枝共聚物，并以此为成膜聚合物，采用非溶剂致相分离法制备PVC基接枝共聚物膜，通过强制表面偏析调控优化PVC基接枝共聚物膜的两亲膜表面性质（抗污染/自清洁协同）与渗透性能，改善膜的抗污染性能；选用牛血清蛋白、腐殖酸、海藻酸钠为过滤介质，对PVC基接枝共聚物膜的过滤性能和抗污染性能进行研究，分析了PVC基接枝共聚物膜的抗污染机理，并建立抗污染模型。成功解决异质增强型中空纤维膜表面分离层与增强体之间界面结合状态不良等关键基础性问题，并显著提高了膜的抗污染性能和使用寿命。.本项目执行期间，就上述有关研究内容已发表学术论文9篇(其中SCI收录6篇，Ei 收录3篇)，申请发明专利4项，获授权发明专利1项。相关研究成果“同质增强型中空纤维膜制备关键技术及其产业化应用”于2018年获天津市技术发明一等奖。