| 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...
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