三羟甲基丙烷三丙烯酸酯-苯乙烯沉淀聚合高产率制备高交联单分散聚合物微球

以三羟甲基丙烷三丙烯酸酯(TMPTA)-苯乙烯(St)为单体,偶氮二异丁腈(AIBN)为自由基引发剂,通过在乙醇中的沉淀聚合可制得高交联单分散P(TMPTA-St)聚合物微球.对单体转化率,微球以及可溶性低聚物的产率进行了测试.结果表明,使用10 wt%至60 wt%的交联剂TMPTA进行聚合可获得单分散微球,产率在50%左右.增加TMPTA用量可提高微球产率和单体转化率.增加引发剂AIBN用量对提高微球产率也有促进作用,但同时可溶性低聚物产率也增加.向乙醇中加入水作为反应介质结合适当增加AIBN用量可使单体转化率达到98%,微球产率高于90%.对实验结果进行了解释,对聚合机理进行了讨论.

TO INCREASE THE YIELD OF UNIFORM AND CROSSLINKED MICROSPHERES OF POLY(TRIHYDROXYMETHYL PROPANE TRIACRYLATE～STYRENE) IN PRECIPITATION POLYMERIZATION

Using trihydroxymethyl propane triacrylate(TMPTA) and styrene(St) as the monomers and 2,2-azobis-(isobutyronitrile)(AIBN) as the initiator,uniform and crosslinked microspheres of P(TMPTA-St) were prepared through precipitation polymerization in ethanol.Monomer conversion,yields of microspheres and soluble oligomers were determined,size and size distribution of the microspheres were examined by scanning electron microscope.Results indicate that uniform microspheres were obtained with 10 wt% to 60 wt% of TMPTA in the monomers with a yield of about 50% for the microspheres at 60 wt% of TMPTA.Monomer conversion and microsphere yield were increased with TMPTA amount.Increase in AIBN was also useful to increase monomer conversion and microsphere yield;the soluble oligomers were also increased at the same time.By adding water in ethanol while keeping AIBN at 2 wt% relative to the monomers,monomer conversion of above 90% was achieved with the yield of the microspheres at about 83%.An optimized protocol,by which about 98% of monomer conversion and 90% of uniform microspheres were achieved,is recommended,in which 26 vol% of water was added to ethanol as the polymerization solvent combined with 6 wt% of AIBN.The results were interpreted and the mechanism of the polymerization was discussed.