物理吸附-自由基引发聚合接枝法PVDF膜表面修饰两性离子刷及性能研究

Zwitterionic polymers have been for surface modification of all kinds of materials due to their outstanding hydrophilicity and anti-fouling properties. However, previous reported grafting methods are easily lead to the degradation of polymer chains. In this project, physisorbed free radical initiating grafting polymerization method，a new method of easily modifying the interior walls of membrane porous without damaging the membrane structure,is to be firstly used to grafted zwitterionic polymer brushes poly(carboxybetaine methacrylate) (PCBMA) and poly(sulfobetaine methacrylate) (PSBMA) on the poly(vinyldene fluoride) (PVDF) microporous membrane. The influences of grafting conditions on the composition, morphology and structure of membrane are to be investigated systematically. And the mechanism and kinetics of this grafting reaction will be discussed thoroughly. The change of hydrophilicity and the anti-fouling properity are to be studied. Furthermore, the PCBMA and PSBMA brush are able to provide a platform for the further functional decoration of PVDF microporous membrane. Via the interactions with the-CO2- and -SO3- in the structure of PCBMA and PSBMA respectively, the TiO2 nanoparticles can be immobilized on the PVDF grafted membranes. The influence of TiO2 immobilization on the structure and self-cleaning property of PVDF membrane will be studied. This research has great significance that it will provide a new approach for the preparation of PVDF organic/inorganic composition membrane with excellent anti-fouling and self-cleaning performances.

两性离子聚合物具有优异的亲水性和抗污染性而常被用作材料表面改性,但普遍使用的接枝方法容易造成聚合物链的降解，从而影响改性效果。本项目拟采用改性效果持久稳定且不会对膜造成损伤的物理吸附-自由基引发聚合接枝新方法在PVDF微孔膜上接枝两性离子刷聚甲基丙烯酸羧酸基甜菜碱（PCBMA）和聚甲基丙烯酸磺酸基甜菜碱（PSBMA），考察接枝条件对膜的组成形态和拓扑结构的影响，探讨接枝反应机理及反应动力学过程，研究接枝反应对膜表面亲水性和抗污染性能的影响；另外，也进一步以聚合物刷 PCBMA 和PSBMA为 PVDF微孔膜的功能化修饰平台，通过PCBMA和PSBMA链上的羧基和磺酸基固载TiO2无机纳米粒子，分析这一过程对膜结构和自清洁性能的影响，研究结果可为制备强抗污染、自清洁 PVDF有机/无机复合膜提供新思路。

本项目已经完成利用物理吸附-自由基引发聚合接枝法在PVDF膜表面接枝两性离子刷PCBMA和PSBMA，改善膜的亲水性、抗污染性和无机盐分离性能等，并对物理吸附-自由基引发聚合接枝法在PVDF膜表面的接枝机理进行了深入的探讨和总结。在研究中我们发现PVDF-g-PCBMA膜对无机盐NaCl、MgCl2和ZnCl2都有不同程度的截留效果，尤其对NaCl溶液的截留率达98%以上。以改性膜为平台的进一步功能化过程中，以具有可见光催化性能的TiO2/Ag无机纳米颗粒为功能物质，通过配位螯合作用将其固载在改性后的PVDF膜表面，制备出一系列具有可见光杀菌性和自清洁性能的PVDF复合膜。对其可见光催化机理进行了系统的研究和探讨。固载TiO2/Ag纳米颗粒的PVDF改性膜自清洁能力非常显著，纯水接触角由原膜的84°下降至40°。渗透性能研究表明，3-4个循环后，膜对牛血清蛋白的水溶液的通量保持在500-700L/m2•h。而且该膜对大肠杆菌和金黄色葡萄糖球菌的可见光杀菌性非常显著，经过可见光照射后的改性膜抑菌圈可达17-20mm直径大小。.本项目目前发表SCI论文6篇,有4-6篇文章正在整理，后续将陆续发表。截止目前共申请发明专利10项，其中授权5 项。培养研究生7名。各项指标均超出预期目标，圆满完成此项课题。