Synthesis And Characterization Of A Novel Hyperbranched Polysilane And Its Composite With Fullerene

Recently, in the world, much attention has been paid on the fundamental research,devices preparing and application of optoelectric polymer materials. Among these, the researches are mainly focused on polymer light emitting materials and polymer photovoltaic materials.To date, the majority of works about the two areas reported in the previous literatures are mainly focused onπ-conjugated polymers, however, there are few works onσ-conjugated polymers. Polysilanes are a new class ofσ-conjugated polymers with the backbone consisting of tetrahedrally coordinated silicon atoms and different side-chain substituent groups. Due to the extensive delocalization ofσ-electrons along the silicon main chain,σ-conjugated polymers have many interesting electronic properties such as photoconductivity with high hole mobility, large nonlinear optical effects and effective UV light emission, which make them a promising application in optoelectric materials, and have drawn the interests of the material scientists. The common use of polysilanes as optoelectric materials has been mainly focused on one-dimensional linear polysilanes. Meanwhile, three-dimensional hyperbranched polysilanes different from linear polysilanes, have better optoelectric properties, such as, red shift of absorption and emission spectra, more large stokes shift, reduced bandgap due to the extent ofσ-conjugation at branching points. And its 3-D structure is very propitious to preparing electron donor/acceptor composite with interpenetrating structure with electron acceptor fullerene. All these make the hyperbranched polysilanes may be good candidates for polymer light emitting and polymer photovoltaic materials.In this work, we report on the synthesis and characterization of a novel hyperbranched polysilane and its composite with fullerene.Based on the previous reports of linear polysilanes, we synthesized a novel hyperbranched polysilane polymethylphenylsilane-co-methylsilane (PMPS-co-MS) via Wurtz-type reaction using dichloromethylphenylsilane and trichloromethylsilane as monomers, which is designed to obtain better optoelectric properties than linear polysilanes. Then, based on the synthesis and theory ofπ-conjugated polymers/fullerene composites, we prepared a novel hyperbranchedσ-conjugated polymer/fullerene using in-situ polymerization, that is synthesized the hyperbranched polysilane in the presence of fullerene. The novel electron donor/acceptor composite may have well defined interpenetrating structure because of 3-D structure of both hyperbranched polysilane and fullerene. We also characterized by means of methods and discussed the structures, properties, and potential applications of the products.After fully studied, we found that: The resulting hyperbranched polysilane synthesized via Wurtz-type reaction shows good solubility in common organic solvents, high molecular weight (Mw=12093), well defined hyperbranched structure, blue fluorescence with a quantum yield about 0.17, good thermal stability, and high glass transition temperature. All these indicate that it may be a good optoelectric material. The composite we prepared shows good solubility, high molecular weight, good thermal stability, well defined interpenetrating structure, effective photoinduced electron transfer indicated by the obvious photoluminescence (PL) quenching, which suggests that it may be a good electron donor/acceptor composite. Further discussion found that there may beπ-πstacking between hyperbranched polysilane and fullerene, which may make the composite have many interesting properties and promising applications.