【作者】 戴清文；

【导师】 徐志康；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2004， 博士

【摘要】 聚丙烯微孔膜具有价格低廉、化学和热稳定性好、机械强度高、无毒、孔隙率容易控制等优点。但是聚丙烯的强疏水性导致聚丙烯膜材料表面亲水性差、易带静电、生物相容性差、膜污染严重，这些缺点制约了聚丙烯微孔膜的应用，对聚丙烯膜材料进行适当改性十分必要。本论文的主要研究内容是采用多种聚电解质对聚丙烯微孔膜进行表面改性，包括弱碱型的聚甲基丙烯酸二甲胺乙酪、弱酸型的聚丙烯酸及其盐、聚阳离子型的聚甲基丙烯酰氧乙基三甲基铵盐以及两性离子聚磷脂酰胆碱。 通过改进的自由基接枝和光引发接枝两种方法制备甲基丙烯酸二甲胺乙酯表面接枝改性的聚丙烯微孔膜。考察了反应温度、单体浓度、引发剂用量、反应时间以及反应介质对接枝反应的影响，用红外光谱对膜表面官能团的变化进行表征，发现以水为反应介质时，甲基丙烯酸二甲胺乙酯在聚合过程中发生水解反应。扫描电镜照片显示，接枝后膜的部分微孔被堵塞。接触角和牛血清白蛋白吸附试验显示，经过接枝改性，提高了聚丙烯膜的亲水性能和抗污染性能。当接枝率为1.6wt．％～2.5wt．％时，改性膜的水通量增加，且稳定性提高。 合成并表征了几种磷脂中间体：2-烷氧基2-氧-1，3，2-二氧磷杂环戊烷，其中烷氧基的碳原子数为8，12，14，16，18等。采用甲基丙烯酸二甲胺乙酯接枝聚丙烯膜与2-烷氧基-2-氧-1，3，2-二氧磷杂环戊烷进行开环反应来制备磷脂改性聚丙烯膜。发现磷脂改性膜中长链烷基存在分子翻转现象，提出了磷脂分子会形成疏水表面和亲水表面两种结构，在一定条件下两种表面会相互转化。考察了分子翻转对接触角、水通量的影响，发现磷脂改性聚丙烯膜具有良好的耐蛋白质污染性能和血液相容性。 将甲基丙烯酸二甲胺乙酷改性聚丙烯膜进行季铵化反应，得到了聚甲基丙烯酰氧乙基三甲基铵盐改性的聚丙烯微孔膜，研究了膜的表面官能团变化以及对膜的亲水性、水溶胀性、水通量的影响。将改性膜用于蛋白质和酶的固定化，发现蛋白质和酶的固定量先随着接枝率增加而减少，接枝率达到2.5wt％～3wt％时，蛋白质和酶的固定量又随接枝率增加而上升。固定到膜上的酶具有较高的活性保留率，达57％。 采用过氧化苯甲酞为引发剂，制备了聚丙烯酸改性聚丙烯膜，研究了反应温度、反应时间、引发剂用量、单体浓度、溶剂以及交联剂对接枝反应的影响，发现加入交联剂后接枝率迅速上升。对聚丙烯酸改性膜的表面成分、结构变化、亲水性能、抗蛋白质污染性能等进行了研究，发现聚丙烯酸改性膜具有很好的亲水性能和抗蛋白质污染性能。当接枝率达到ZOwt.%以上，聚丙烯膜可以从微孔结构变为致密结构，并用改性膜作为渗透汽化膜研究了醇水混合物的分离行为。研究了接枝率、交联度、进料温度、配对离子等对分离性能的影响，发现聚丙烯酸改性膜和金属离子化后的丙烯酸改性膜都具有优先透水性，用金属离子置换丙烯酸中的H十，能提高膜的选择性。不同金属离子对选择性和渗透通量具有很大的影响，分离因子按下列次序递减:A尸十>K--+>ca“+>Na+>Li十，渗透通量按下列次序递增:A尸+<ca升<K+<Na+<Li+。同丙烯酸修饰的聚丙烯膜相比，用Als+置换后，渗透通量明显增加，但是分离因子没有下降。更多还原

【Abstract】 Microporous polypropylene membrane has many desirable properties including high void volumes, well-controlled porosity, chemical intertness and low cost. However, polypropylene membrane is hydrophobic and poor-biocompatible, which lead to serious fouling and limit the membrane use in many fields. In order to enlarge the applications of the microporous polypropylene membrane, it is very necessary to alter the chemical and physical properties of PP membrane surface. Polyeletrolytes are an important class of functional polymers used to modify polymeric membrane. In this thesis, four kinds of polyelectrolyte, including poly(N,N-dimethylaminoethyl methacrylate), poly(phosphorylcholine), poly(methacryloyloxyethyltrimethylammonium) and poly(acrylic acid), are used to modify the surface of microporous polypropylene membrane.N,N-dimethylaminoethyl methacrylate (DMAEMA) is well-known for its biocompatibility and amphiphilicity. Surface modification of microporous polypropylene membranes was performed by radical-induced and photo-induced graft polymerization of N,N-dimethylaminiethyl methacrylate. The factors effected the graft polymerization, such as temperature, monomer concentration, the amount of initiator, were studied respectively. It was found that the monomer hydrolyzed during the graft polymerization when water was used as solvent. Scanning electron microscopy (SEM) pictures demonstrated that part of the micropore was plugged, especially at high grafting degree. Water contact angle measurement showed that moderate grafting degree could improve the membrane hydrophilicity. At the range of 11.30wt.%~12.05wt.% grafting degree, the contact angle reached its minimum (about 74?. The modified membrane at low grafting degree near 1.59~2.52wt.% showed high and stable flux for ultrapure water. The BSA adsorption experiment indicated that DMAEMA had a dual effect on protein adsorption. At the first stage, the amount of membrane absorbed BSA reduced with the increase of DMAEMA grafting degree. After 14.62wt% grafting degree, the absorbed BSA increased with the increase of DMAEMA graft degree.After grafting with DMAEMA, the DMAEMA-grafted polypropylene membranes were reacted with 2-alkyloxy-2-oxide-l,3,2-dioxophospholanes to formHIpoly(phosphorylcholine)-modified polypropylene membranes. Five2-alkyloxy-2-oxide-l,3,2-dioxophospholanes, containing octyloxy-, dodecyloxy-, tetradecyloxy-, 2-hexadecyloxy- and octadecyloxy- groups in the molecular structure respectively, were synthesized and used for the above reation. The FT-IR spectra of the original, the DMAEMA-grafted and the phospholipid polymer modified membranes were used to confirm the change of chemical components on the membrane surface. The turning-over of phospholipid molecules were found, which gave an effect on the water contact angle and water flux. The adsorption experiment of BSA demonstrated that the five kinds of phospholipid-modified membranes had better anti-fouling ability than the unmodified PP membrane and the DMAEMA-modified membranes. For hexadecyloxy-including and octadecyloxy-including membranes, above 6% grafting degree, the membrane was protein-resistant. Platelet adhesion was well suppressed on the phospholipid-modified membranes.DMAEMA-grafted polypropylene membranes were also used to form poly(methacryloyloxyethyl trimethylammonium)-modified PP membranes by treating with methyl iodide. The characteristics of poly(methacryloyloxy ethyl trimethylarnmonium)-modified PP membrane, such as the change of functional group on the membrane surface, the hydrophilicity, water swelling and water flux, were studied. BSA and Candida rugosa lipase were immobilized on the ammonium-modified PP membranes. It was found the protein immobilized on the membrane surface decreased with increasing of the graft drgree before the graft degree reach 2.5wt%~3wt%. Above this point, the protein amount immobilized on membrane surface increased. The enzyme immobilized on the ammonium-modifiedPP membrane showed high yi更多还原