紫外光引发硅氢加成反应制备超支化聚碳硅氮烷

在二乙酰丙酮铂存在下, 以紫外光引发AB4型单体双(N,N-二烯丙基胺基)甲基硅烷发生硅氢加成反应, 制备了超支化聚碳硅氮烷. 聚合产物通过FTIR, 1H NMR, 13C NMR和29Si NMR谱和体积排除色谱/激光光散射联用技术进行表征. 与常规加热条件下Karstedt's催化剂催化的硅氢加成聚合相比, 光引发聚合的反应速度快. 波谱分析表明, 聚合过程中以α位硅氢加成反应为主. 光引发聚合制备的超支化聚碳硅氮烷支化度(DB)和平均支化数(ANB)分别为0.46和0.53, 与理论值相近. 其重均分子量为12500 g/mol, 分子量分布系数为2.1, Mark-Houwink方程指数α为0.44, 与热聚合制备的超支化聚碳硅氮烷的参数相近.

Preparation of Hyperbranched Polycarbosilazane via Ultraviolet Initiated Hydrosilylation

Hyperbranched polycarbosilazane P1 was successfully prepared from AB4 type monomer bis(N,N-diallylamino)methylsilane via fast hydrosilylation initiated by ultraviolet(UV) irradiation, with bis(acetylacetonato)platinum(Ⅱ) as the catalyst. For comparison, hyperbranched polycarbosilazane P2 was also prepared with the same monomer via heating-initiated polymerization at 80 ℃ with Karstedt's catalyst. The structures of the resulting polymers were well characterized by FTIR, 1H NMR, 13C NMR, 29Si NMR and size exclusion chromatography/multi-angle laser light scattering(SEC/MALLS) technology. By IR monitoring, it was found that polyhydrosilylation initiated by UV irradiation was much faster than that initiated by heating. NMR analyses confirmed that the resulting polymer possessed a hyperbranched architecture, indicating that α-hydrosilylation may mainly occur during UV-initiated polymerization. Degree of branching(DB) and average number of branches(ANB) of P1 were determined via 29Si NMR and were found to be 0.46 and 0.53, which were close to the theoretical values, respectively. And the weight average molecular weight, polydispersity index and exponent for Mark-Houwink equation of P1 were determined to be 12500 g/mol, 2.1 and 0.44, respectively, which were similar to those of P2.