Preparation of Chitosan-g-PAMPS in H2O/scCO2 Inverse Emulsion

Chitosan(CS)was successfully modified in supercritical carbon dioxide(scCO2)by grafting method to enhance its water solubility.In this work,a three-arm star-like fluorinated polymer was synthesized by atom transfer radical polymerization(ATRP)method and applied as a surfactant in supercritical carbon dioxide(scCO2).Then 2-acrylamido-2-methyl propane sulfonic acid(AMPS)was grafted onto CS(CS-g-PAMPS)in H2O/scCO2inverse emulsion.The effects of mass ratio of water and surfactants(R w/s)and pressure of scCO2on the grafting reaction were investigated.The grafting rate,particle size,and dispersity in water of CS-g-PAMPS varied greatly as R w/s and pressure of scCO2changed.It could be found that the value of R w/s at 12 and the pressure of scCO2at 30 MPa were the optimum conditions for the grafting reaction.CS-g-PAMPS prepared in this reaction system has higher grafting rate,smaller particle sizes,and better dispersity in water than those prepared via conventional methods.     

超临界二氧化碳中原位分散聚合制备PSAN/OMMT纳米复合材料

采用原子转移自由基聚合（ATRP）合成了结构可控、分子量分布窄的含氟嵌段共聚物聚（苯乙烯-无规-丙烯腈）-嵌段-聚甲基丙烯酸全氟辛基乙酯（PSAN-b-PFOMA）。并以此共聚物为稳定剂,在超临界二氧化碳（ScCO2）介质中采用原位分散聚合制备了聚苯乙烯-丙烯腈/蒙脱土（PSAN/OMMT）纳米复合材料,并采用小角X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、透射电镜（TEM）和热失重分析（TGA）对产物的结构和热性能进行了表征。结果表明：与PSAN相比,PSAN/OMMT纳米复合材料的耐热性和热稳定性有所提高;通过调节蒙脱土的含量,可以制备形态结构不同的PSAN/OMMT纳米复合材料;该复合材料的耐热性和热稳定性在蒙脱土质量分数为0.05时达到最佳。