Ce(Ⅳ)盐引发丙烯腈在交联聚乙烯醇微球表面的接枝聚合

以戊二醛为交联剂,在反相悬浮体系中采用直接交联反应成球的方法,制备了聚乙烯醇(PVA)。以硫酸铈铵为引发剂,在酸性溶液聚合体系中实施了丙烯腈(AN)在交联微球CPVA表面的接枝聚合,制备了接枝微粒CPVA-g-PAN,考察了主要因素对交联成球反应与接枝聚合的影响规律。实验结果表明,在一定的搅拌速度下,分散剂用量及油水两相比是影响交联微球CPVA的主要因素。在Ce(Ⅳ)盐的氧化作用下,在含有大量羟基的CPVA微球表面会产生自由基,顺利地实现丙烯腈的自由基接枝聚合反应。反应温度、铈盐浓度和H+离子浓度是影响接枝聚合反应的主要因素。在适宜条件下,可制得PAN接枝度为27 g/100 g的接枝微球CPVA-g-PAN。

Graft Polymerization of Acrylonitrile on Crosslinked Polyvinyl Alcohol Microspheres Initiated by Cerium Salt

Crosslinked polyvinyl alcohol(CPVA)microspheres were prepared via direct crosslinking and balling reaction of polyvinyl alcohol with glutaraldehyde as crosslinker in a reverse phase suspension system.The graft polymerization of acrylonitrile on CPVA microspheres was performed in an acidic solution polymerization system by using cerium ammonium sulfate as initiator,and grafted microspheres CPVA-g-PAN were prepared.The experimental results show that in the direct crosslinking and balling system,the used amount of disperser and the ratio of oil phase to water phase are two main factors which affect the grain size of crosslinked microspheres CPVA.The radical graft polymerization of PAN on CPVA microspheres initiated by cerium salt can be realized smoothly because free radicals are produced on the surface of CPVA microspheres by the cerium salt oxidation of hydroxyl groups on CPVA.The reaction concentration,concentration of the initiator and cerium salt obviously affects the graft degree of PAN. Under suitable conditions,the grafted microspheres CPVA-g-PAN with a graft degree of 27 g/100 g can be obtained.