用于原子转移自由基聚合的新型固载催化体系

New Immobilized Catalyst System for Atom Transfer Radical Polymerization

用油酸和二乙烯三胺合成了新型配体油酸咪唑啉(OLC),并通过化学方法将OLC固载在硅胶表面得到SiO2-OLC,SiO2-OLC再与CuBr或CuCl2形成硅胶固载催化剂(CuBr/SiO2-OLC或CuCl2/SiO2-OLC),并将该催化剂用于以2-溴代丙酸乙酯为引发剂、甲基丙烯酸甲酯为单体的原子转移自由基聚合(ATRP)反应。用元素分析和FTIR手段对催化剂的结构进行了表征,用GPC手段对聚甲基丙烯酸甲酯的相对分子质量及其分布进行了表征。实验结果表明,使用CuBr/SiO2-OLC和CuCl2/SiO2-OLC催化剂时,ATRP反应均符合一级反应动力学规律,为活性/可控聚合反应;聚合物的相对分子质量分布较窄(前者为1.25,后者为1.33);用CuCl2/SiO2-OLC催化剂合成的聚合物溶液清澈透明,催化剂可以回收再利用,但活性有所降低。

2-（ 8-heptadecenyl ） -4, 5-dihydro-t H-imidazole-l-ethylamine （ OLC ） was synthesized from cis-9-octadecenoic acid and divinyl-triamine. CuBr/SiO2-OLC and CuCl2/SiO2-OLC catalysts were prepared separately through chemically immobilizing OLC on silica gel surface to obtain SiO2- OLC and then interacting SiO2-OLC with CuBr or CuC12. The catalysts were used in atom transfer radical polymerization （ATRP） of methyl rnethacrylate with ethyl 2-bromopropionate as initiator. The catalysts were characterized by means of elemental analysis and FTIR. Relative molecular mass and its distribution of the poly （methyl methacrylate） obtained through the ATRP were measured by means of GPC. The result showed that kinetics of the ATRP catalyzed by CuBr/SiO2-OLC or CuC12/SiO2-OLC was first order reaction, relative molecular mass of the obtained polymer increased linearly with monomer conversion, which indicated the ＇ living ＇ /controlled nature of the polymerization, and relative molecular mass distribution of the polymer was low （the former was 1.25 and the latter was 1.33）. The polymer solution obtained with CuC12/SiO2-OLC catalyst was transparent and the catalyst could be reused.