Synthesis And Properties Of Antimony-Substituted Poiysilane

Polysilanes are polymers with entirely silicon atoms constructed main chains, -Electrons in the main chains of polysilanes are strongly delocalized, and energy gaps of the -electrons are 3~4eV. Conductivity of polysilanes is 10-12~10-15S/cm, and can be adjusted from 10-8 to 10-1 S/cm, even up to 0.2S/cm by doping. Their excellent photo-electric properties make polysilanes be used as fuctional materials, such as semi-conductors, photoconductors, nonlinear optical materials, and so on.In this dissertation, polymethylsilane (shorted as PMS), a highly reactive polymer, was synthesized as the initial polymer for preparation of antimony-substitued polysilane (shorted as APS). The PMS and its derivatives were characterized by FT-IR, element analysis, 1H-NMR, 29Si CP/MAS NMR, GPC, UV, and TGA to investigate the molecular composition and structure, molecular weight, stability, etc. The APS was doped by iodine, and its semi-conductor property was studied.PMS was synthesized by the Wurtz reductive coupling reaction of methyldichlorosilane, and its chemical composition was [(MeHSi)0.73(MeSi)0.27]n. Polychloromethylsilane (shorted as PCMS) was prepared by chlorination of carbon tetrachloride and PMS under mild conditon. The chlorination appeared to be highly selective for Si-H bonds, and more than 90% of the Si-H bonds were substituted.APS was synthesized via the following two ways. One way was to synthesize APS through reaction of PMS and SbCl3. Using THF as the solvent and pyridine as the catalyst, the reaction could proceed with fewer side reactions, and APS with chemical composition of [(MeHSi)0.33(MeSi)0.57(MeSiSb)0.10]n was obtained. The other way was to synthesize APS through reaction of PCMS and SbCl3. With the connection of Si-Sb bonds, APS synthesized through the above twoways was branched and crosslinked. Electric conductivity of the APS was among 10-8~10~7S/cm, and thus it belongs to semi-conductor. The electric conductivity was improved to 10-5S/cm when the APS doped with iodine in 7-8 hours, and the electric conductivity could maintain for 72h. The doping mechanism was also discussed.