Modification of polysulfone through homogeneous UV-induced graft copolymerization and its preparation of membrane

紫外光接枝改性法以其反应条件温和、易于操作、设备简单等优点，近年来得到广泛重视。 本论文首次提出在均相溶液体系下对聚砜膜材料进行紫外光接枝改性，即以聚砜（PSF）为基材，以二苯甲酮为引发剂，丙烯酸或丙烯酸甲酯为单体，二氯甲烷为溶剂，通过紫外光引发经过交联聚合而形成接枝共聚物，并通过相转移法制备具有亲水性、耐污染或pH敏感性的膜。 对接枝共聚物进行了1H NMR谱图、红外光谱、XPS能级谱图和TG热重分析，结果均表明在均相溶液体系下，丙烯酸或丙烯酸甲酯与聚砜发生了紫外光引发的接枝共聚反应。 实验表明丙烯酸加入聚砜链上能有效的提高接枝共聚物膜的亲水性，接触角从68°下降至32°左右，但静态和动态膜污染实验均表明聚砜接枝丙烯酸的共聚物膜并不能减少蛋白在膜表面的吸附。而将丙烯酸甲酯接枝到聚砜链上，不仅能有效提高膜表面的亲水性，接触角从68°下降至51°左右， 而且能减少蛋白在膜表面的吸附，控制膜污染；接枝率为14.89 %为接枝共聚物膜的总水通量损失率比纯聚砜膜小了59%，清洗后水通量恢复率比纯聚砜膜高67%。 采用相转移法，以聚砜与丙烯酸接枝共聚物和纯聚砜为共混基材，可制备出具有pH响应性的环境敏感共混膜；不同pH值下的水通量实验结果表明，含接枝共聚物的共混膜具有明显的pH敏感性，在pH=26之间，共混膜通量随pH值的升高而急剧下降，纯聚砜膜没有明显的pH敏感性；pH值响应系数最高的约为5。The method and technology of UV-induced graft modification gets much more attention as they have the characteristics of mild reaction condition, easily controlled and simple equipment. The modification of polysulfone(PSF) was carried out by homogeneous UV-induced graft polymerization. Graft copolymers were synthesized by irradiating homogeneous solutions of PSF, acrylic acid or methyl acrylate monomers，and benzophenone photoinitiator with UV light. Then, the obtained graft copolymers were cast for hydrophilic, anti-fouling or pH sensitive membrane by the phase inversion method. The graft copolymers were characterized by 1H NMR spectroscopy, XPS spectrometer, attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FTIR) and thermogravimetric analyze (TGA). These results verified that acrylic acid or methyl acrylate groups were present on the polysulfone polymer. The experiment results showed that the hydrophilicity of polysulfone-graft- acrylic acid copolymer membranes was improved and the contact angle value decreases from 68° to 32°. However, static and dynamic membrane fouling indicated that protein adsorption on the membrane surface could not be reduced by grafting acrylic acid onto polysulfone. Grafting methyl acrylate onto polysulfone not only improved the hydrophilicity of membrane surface from 68° to 51° of the contact angle value, but also the membranes showed an enhancement of antifouling property. The total flux loss of the polysulfone-graft-methyl acrylate copolymer membranes with 14.89% graft degree was 59% little than of the nascent polysulfone membrane, and the pure water flux loss after washing was recovered to be 67% higher than of the nascent polysulfone membrane. The pH sensitive blend membrane was prepared by casting an aqueous solution of polysulfone-graft-acrylic acid copolymers and polysulfone as basic phase. The results by measuring the water filtration flux changes on different pH values showed that pH responsibilities of the blend membrane with graft copolymers had been observed and the water flux obviously reduced with the increase of pH values in the range of 26, but the nascent polysulfone membrane had not the pH responsibilities. The pH responsive coefficient reached the highest about 5