Synthesis Of New Polysilane And Performance

Although the first substituted polysilanes were probably prepared in the I 920s,these and related materials were poorly characterized, were intractable, and elicitedlittle scientific interest for almost 50 years. The synthesis in the late 1 970s has causedan explosive rebirth of interest in polysilanes that continues today. Much work hasbeen done in the 20 years, including the synthesis of homo- and co-polymers, studiesof the electronic structure of ground and excited states, UV and fluorescencespectroscopic studies, various aspects of polymer structure both in solution and in thesolid state, the photochemistry of substituted polysilanes and finally potentialapplications. On the basis of such studies, this paper deals mainly with the preparingof substituted polysilanes, the electrochemical polymerization method and thesynthesis of dendrimer polysilane.First, in this paper, (PhSiMe)_n are synthesized from dichlorosilanes in the Wurtzcoupling reaction. The reactions in hexane solution between the polysilanes and acetylchloride, acid anhydrides [(CH3CO)20, (C2H50),O, C4H203, C8H403] and ester(CH3COOC2H5) can lead to acyoxy groups substituted polysilanes. These provide anovel approach to synthesizing substituted polysilanes, which can introduce acyoxygroups onto silicon main chain directly. The reaction steps and the influence factorsare tentatively suggested. All the resultants were characterized by 'H NMR and IRmeasurements and their UV absorbency and fluorescence emission-excitation spectraare also studied.Furthermore, using dimethoxylsilanes as monomers to replace dichlorosilanes, westudied their electroreductive polymerization process. The synthesis method wascompared with other methods and showed that although the yields were relatively low,this method can give polysilanes with more simplex structure and simplify?reactionconditions. These provide a simple and available novel approach to preparingpolysilanes, which worth to be developed further.Some dendrimer polysilanes were also synthesized through Grignard method andWurtz coupling method in this paper. In the experiment, CH3Ph2SiCI was used asmonomer and CH3SiC13 as core molecule. The polysilane is a novel polymer that hasnever been reported before. The probable reaction steps were tentatively suggestedand the reaction ratios were calculated using chlorine content data. It is found that itwasn抰 the reaction of monomer with core molecule but the reaction of phenyl thatdominated the dendrimer抯 synthesis. Although there are many flaws in the resultpolysilanes, they still showed very strong fluorescence. This certified such dendrimerpolysilanes could be applied in optical materials.