Synthesis And Characterization Of Heat-resistant Boron-containing Hydrogen Silicone Oil

Hydrogen-containing silicone oil has been widely used in the preparation of silicone rubber,LED packaging and hydrophobic materials.However,due to its low heat resistance,its application is often limited.In this paper,two kinds of heat-resistant boron-containing hydrogen silicone oil were prepared,and the related research is as follows:(1)Boron-containing hydrogen silicone oil(BHSO-M)was prepared from methyl boric acid(MBA),methyl dichlorosilane(MDC),dimethyl dichlorosilane(DMDC)and hexamethyldisiloxane(MM).The effects of raw material ratio,reaction temperature,reaction time on the heat resistance of BHSO-M were studied.The optimal reaction condition was as follows:the mole ratio of MBA and MDC was 1.5:1,the temperature was 50?and reaction time was 7 h,the BHSO-M-1.5 had the best thermal stability,and its hydrogen content was 0.11%,molecular weight was 11165.T₅,T₁₀and T_maxof BHSO-M-1.5 was 385.2?,421.4?and 579.2?,respectively.The structure of BHSO-M was characterized by FT-IR and NMR.Boron-containing vinyl silicone oil(BVSO-M)was prepared by DMDC,MBA and divinyltetramethyldisiloxane,and the content of vinyl was 0.2671 mmol/g.Heat-resistant boron silicone rubber(BSR-M)was prepared by using BHSO-M as curing agent of BVSO.The surface B content of BSR-M was measured to be 8.74%by XPS.The highest activation energy of the decomposition process of BSR-M was74.42 kJ/mol and the residual carbon content was more than 61%at 800?,which was higher than that of ordinary silicone rubber.The decomposition process of oligomer and side group was analyzed by TG-IR.(2)Boron-containing hydrogen silicone oil(BHSO-P)was prepared from phenyl boric acid(PBA),MDC and DMDC.The optimal conditions for preparing BHSO-P was as follows:the molar ratio of PBA to MDC was 1:1,the reaction temperature was50?,and the reaction time was 5 h,the BHSO-P-1 prepared had the best heat resistance.The hydrogen content of BHSO-P-1 was 0.086%and the molecular weight was 7960.The T₅,T₁₀and T_maxof BHSO-P-1 reached to 371.7?,411.8?and 574.3?,respectively.The structure of BHSO-P was demonstrated by FT-IR,NMR and UV-Vis.Boron-containing vinyl silicone oil(BVSO-P)was prepared by DMDC,PBA and divinyltetramethyldisiloxane,and the vinyl content was 0.3079 mmol/g.The molecular structure of BVSO-P was confirmed by FT-IR,NMR and other methods.Boron-containing silicone rubber(BSR-P)was prepared by using BHSO-P and BVSO-P as raw materials.The content of B element was measured to be 8.88%.The results show that the apparent activation energy of thermal decomposition of BSR-P is higher than that of BSR-M,and the temperature at the maximum decomposition rate of BSR-P is higher than that of BSR-M,which may be caused by steric hindrance effect of phenyl group.