磺化SEBS质子交换膜制备和性能的研究

Study on synthesis and performance of sulfonated SEBS for proton exchange membranes

利用'预混法'对苯乙烯-乙烯/丁二烯-苯乙烯三嵌段共聚物(SEBS)进行了磺化,采用溶液-浇铸法成膜,并对其制备过程和膜的性能进行了研究.结果表明,FT-IR分析判断磺酸基团接入PS段的苯环对位上;该法平均磺化效率为12%;溶剂DCE与环己烷的加入量体积之比为8:1左右时磺化度达到最高;电导率、含水量、溶涨率和水合系数都以磺化度为15%左右处为一临界点,此前都增长缓慢,此后迅猛增长,然后前三者在磺化度为20%左右增加趋于缓慢,不同的是,而由于'亲水区域'的存在,水合系数在磺化度为20%左右达到最高,随后便逐渐减小;当磺化度达到40%以上,膜的几乎成为水溶性;AFM研究表明磺化后PS相以大小为20～30nm的柱状存在,并有交叉汇合的趋势.

A hydrocarbon proton exchange membrane, the sulfonated styrene-hutylene/ethylene-styrene （s-SEBS） three blocks copolymer membrane, was prepared by the method of solution casting. The process of synthesis and the performance of membranes were studied. The sulfonic groups determined by a FT-IR were just on the para-positions of phenyls of PS blocks. The average sulfonation efficiency of the method was about 12 percent. Sulfonation degree would reach the peak when the volume ratio between DCE and the cyclohexane added was about 8：1. The conductivity, water uptake, swelling and hydration coefficient all increase drastically when sulfonation degree comes to 15 percent, which exhibits the percolation threshold. Then the first three keep increasing with the sulfonation degree growing and then gradually become slow. The membranes would be solvent in the water when the sulfonation degree was over 40 percent. Furthermore, due to the hydrophilic domain, hydration coefficient comes to the peak when the sulfonation degree was about 20, but then decreases. AFM shows that sulfonated PS phases are the cylinder structure with 20～30nm and have confluent trend.