Preparation And Properties Of High Performance Silicone Resin

Polysiloxane has the performance of both inorganic and organic, and its side chain can be connected to the vinyl, phenyl and methyl. The amount and type of groups in side chain determines the nature of polysiloxane in largely. Introducing benzocyclobutene into polysiloxane can improve its comprehensive performance obviously, especially the thermal stability. This thesis designed and synthesized 4-(1, 1-dimethyl-1-hydrogen) silylbenzocyclobutene(4-DMHSBC B) and a series of polymethylvinylsiloxane with various amounts of vinyl. Introducing 4-DMHSBC B into the polymethylvinylsiloxane by hydrosilylation, and the thermal stability of the modified products were be studied.With octamethylcyclotetrasiloxane(D4) and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane(D4vi) as the monomer, tetramethyl ammonium hydroxide as catalyst, dimethyl sulfoxide as the promoter, a series of polymethylvinylsiloxane with various amounts of vinyl were obtained via anionic ring opening polymerization. The test results of fourier infrared spectroscopy(FT-IR) and gel permeation chro matography(GPC) show that the molecular weight of polymers influenced by the content of catalyst, the type of termination agent and the mole ratio of polymerization monomer. With the increase of catalyst's mole ratio, molecular weight increased; among the four kinds of termination agent trimethylchlorosilane, dimethyldichlorosilance, dioctyldichlorosilane and 1-chlorooctane, product with higher molecular weight and more narrow molecular weight distribution was obtained while 1-chlorooctane as catalyst; the molecular weight of copolymer is higher while D4vi: D4 = 1:4.With 4-bromobenzocyclobutene(4-BrBC B) and dimethylchlorosilane as raw material, through grignard reaction got 4-DMHSBCB. Under the condition of the Pt/C as catalyst, 4-DMHSBCB was been grafted to D4 vi and the polymethylvinylsiloxane. The test results of Nuclear magnetic resonance(1H-NMR), thermogravimetric(TG) and differential scanning calorimetry(DSC) show that the catalyst concentration, grafting monomer concentration, polymer molecular weight, etc all can affect the grafting amount. The relationship between the grafting amount of monomer/polymer and thermal stability were linear and nonlinear respectively.