可控降解超支化聚碳硅氮烷的合成与表征

通过锂化四甲基二乙烯基二硅氮烷分别与甲基氢二氯硅烷和二甲基氢氯硅烷的亲核取代反应合成了AB4和AB2型单体AB4M和AB2M,两种单体通过Karstedt催化剂催化的硅氢加成反应分别生成聚碳硅氮烷PAB4M和PAB2M.单体和聚合物的结构通过FT-IR、1H-NMR、13C-NMR、29Si-NMR和体积排除色谱-多角度激光光散射联用(SEC-MALLS)技术进行了表征,结果表明,单体的结构与设计结构相符合;单体聚合时主要以α-硅氢加成方式为主;聚合物具有超支化结构并由N(Si—C)3链节和大量端基双键组成.PAB4M和PAB2M的重均分子量分别为7800和5860g/mol,分子量分布系数分别为2·54和2·31·对PAB4M稳定性的初步研究表明,该聚合物对氯硅烷和在中性条件下对水稳定,但在HCl水溶液中可以降解,且通过控制HCl浓度可以调节其降解速度,从而实现对其控制降解.

SYNTHESIS AND CHARACTERIZATION OF HYPERBRANCHED POLYCARBOSILAZANES WITH CONTROLLABLE DEGRADATION BEHAVIOR

Two novel degradable hyperbranched polycarbosilazanes were synthesized via hydrosilylation reaction and well characterized by FT-IR,1H-NMR,13C-NMR,29Si-NMR and size exclusion chromatogram-multi-angle laser light scattering(SEC-MALLS) technology.First,two monomers,bis(N,N-bis(dimethylvinylsilyl)amino)-methylsilane(AB-4M) as well as(N,N-bis(dimethylvinylsilyl)amino)-dimethylsilane(AB-2M),were prepared by nucleophilic substitution of MeHSiCl-2 and Me-2HSiCl with lithium teramethyldivinyldisilazane,respectively.Then the two monomers were polymerized for obtaining hyperbranched polycarbosilazanes via hydrosilylation reaction using a Karstedt catalyst.The structure analyses indicate that α-addition mainly occurs during the polymerization,and the polymers synthesized consist of N(Si—C)-3 linkages with hyperbranched architecture and a large amount of functional vinyl bonds as end groups.The molecular weight(M-w) and its polydispersity index(M-w/M-n) were determined to be 7800 and 2.54 for PAB-4M,and 5860 and 2.31 for PAB-2M,respectively.Preliminary studies on the chemical stability of polymers shows that the hyperbranched polymer synthesized is stable to chlorosilane as well as water.However,it can be hydrolyzed with hydrochloric acid solution,and the degradation rate can be controlled by changing the concentration of HCl.The results suggest that controlled degradation of these hyperbranched polymers is attainable.