超临界二氧化碳体系中PVDF微孔膜的表面接枝改性

超临界二氧化碳（SCCO2）是一种T〉31．1℃，P〉7．38MPa的二氧化碳流体，不仅具有类似于气体的粘度和类似于液体的密度，而且可以通过改变温度或压力控制SCCO2的密度及溶解性．SCCO2对有机小分子具有优良的溶解、扩散和渗透性能，化学惰性，无污染，易于分离，作为一种聚合反应介质，受到学术界日益增多重视．SCCO2极低的粘度使其具有良好的流动性和扩散渗透性能，零表面张力使其对聚合物具有良好的润湿和增塑性，这将促进引发剂和聚合单体向微孔膜的外表面及内表面扩散．利用温度和压力改变SCCO2的溶解性能调整单体在聚合物相和SCCO2相之间的分布，进而控制微孔膜内外表面的接枝程度．所以SCCO2接枝聚合反应对于聚合物膜的表面改性具有极其重要的意义．

SURFACE MODIFICATION OF PVDF POROUS MEMBRANE IN SUPERCRITICAL CARBON DIOXIDE FLUIDS

Grafting of maleic anhydride/styrene onto PVDF porous membrane was performed in the presence of supercritical carbon dioxide (SCCO_2) as a solvent and swelling fluid.The copolymer of maleic anhydride and styrene (SMA) was grafted onto the out and inner surface of PVDF pores membrane by passing through the membrane pores,which was confirmed by ATR-FTIR and XPS measurements.The SEM photographs of the grafted membrane showed that the membrane structure was hardly changed,except for some jams of the out surface.It was found that the water contact angle of the out surface was reduced more than the inner surface.The membrane biocompatibility corresponding to protein adsorption was improved significantly with the grafting of SMA onto the surface of the PVDF membrane.The effects of SCCO_2 pressure and the comonomer and initiator concentrations were invesgated.