Study On The Synthesis And Property Of Vinylphenypolysilsesquioxane

Vinylphenylpolysiisesquioxane was a new type of inorganic-organic hybrid material,with inorganic Si-O bond as skeleton,each silicon atom connected with a phenyl,which made it have excellent thermal stability,anti-ultraviolet,high refractive index and light transmittance,its spatial dimension was much higher than the ordinary polysiloxane,which made it have important development and application prospect.With one-step process,vinylphenylpolysilsesquioxane(VPPS-1)was synthesized through hydrolysis and condensation method using phenyltrimethoxysilane and dimethylvinylethyoxysilane as raw materials,Iso-Propyl alcohola as solvent in acid condition.The influence of the amount of HCl on the properties of VPPS-1 was significant.And there was little-OMe residue.The degree of condensation reached 94.38%.The thermal degradation mechanism was nucleation and growth process and its reaction order was 4.Its thermal decomposition kinetics equation was d?/dt=7.25×1013(1-?)[-ln(1-?)]-3 exp(-2.85×104/T).With xylene as solvent,the thermal degradation of the synthetic VPPS-2 experienced two stages.In the first stage,the thermal decomposition mechanism was nucleation and growth process and its reaction order was 3/4.And we can also get its thermal decomposition kinetics equation was d?/dt=4×105(1-?)[-ln(1-?)]1/4 exp(-7.00×103/T).In the second stage,the thermal decomposition mechanism was nucleation and growth process and its reaction order was 4.Its thermal decomposition kinetics equation was d?/dt= 2.08×1013(1-?)[-In(1-?)]-3 exp(-2.75×104/T).With two-step process,phenylpolysilsesquioxane(HPPS-1)was synthesized through hydrolysis and condensation method using phenyltrimethoxysilane as raw materials in acid condition.Phenylpolysilsesquioxane(HPPS-2)was synthesized through hydrolysis and condensation method using phenyltrimethoxysilane as raw materials in acid condition firstly,then used basic catalyst.GPC analysis shows that the addition of basic catalyst can improve the molecular weight of phenylpolysilsesquioxane greatly.The initial thermal degradation products were CO2 and H2O.As temperature was increased successively,the thermal degradation products became oligomer polysilsesquioxane and the organic groups decomposed into benzene and its derivatives.VPPS-3 was synthesized by using HPPS-I as raw.The influence of reaction temperature on the mass fraction of vinyl of VPPS-3 was obvious.Using ethyl acetate as solvent,the mass fraction of vinyl significantly improved,but the product was yellow,so toluene was optimal choice.In the reaction,almost all PTMS were condensation and DOC reached 95.35%.The thermal degradation products of VPPS-3 were oligomer polysilsesquioxane,benzene and its derivatives.Its thermal decomposition mechanism was nucleation and growth process,its reaction order was 3,its thermal decomposition kinetics equation was d?/dt= 3.6/×109(1-?)[-ln(1-?)]-2 exp(-1.85×104/T).VPPS-4 was synthesized by using HPPS-2 as raw.The difference of catalyst had an important effect on VPPS-4.Sulfuric acid gave rise to badly yellow.Through the addition of p-toluenesulfonic acid could improve the mass fraction of vinyl,the products was yellow slightly.So the HCl was best choice.The effect of reaction temperature on the mass fraction of vinyl.was unconspicuous.The change of the concentration of HCl had an important influence on the mass fraction of vinyl of VPPS-4 and the best concentration of HCI was 3wt%.The synthetic VPPS-4 had a high molecular weight,little Si-OH and DOC reached 95.95%.The thermal degradation of the synthetic VPPS-4 experienced two stages.In the first stage,the thermal degradation products were oligomer polysilsesquioxane and a little CO2 and H2O.its thermal degradation mechanism was nucleation and growth process and its reaction order was 4.Its thermal decomposition kinetics equation was d?/dt=7.0 × 1017(1-?)[-ln(1-?)]-3 exp(-3.57×104/T).d?/dt=3.25×1017(1-?)[-In(1-?)]-3 exp(-2.73×104/T).In the second stage,the thermaldegradation products were a lot of benzene and its derivatives.Its thermal degradation mechanism was nucleation and growth process and its reaction order was 4.-And its thermal decomposition kinetics equation was d?/dt=5.37×1015(1-?)[-In(1-?)]-3 exp(-3.60 × 104/T).To further improve the refractive index of vinylphenylpolysilsesquioxane,the diphenyldimethoxysilane(DPDMS)was added in later stage reaction.The addition of DPDMS could significantly improve the refractive index of HVPPS from 1.5582 to 1.5921.The thermal degradation of HVPPS was complex and it can be divided intothree stages.In the first stage,it was the volatilization of linear oligomer.Its thermal degradation mechanism was one dimensional diffusion and the thermal decomposition kinetics equation was d?/dt=4.84×107 1/2?-1 exp(-9.02×103/T).In the second stage,there were a lot of oligomer polysilsesquioxane,benzene and its derivatives.Its thermal decomposition mechanism was nucleation and growth process and its reaction order was 4.Its thermal decomposition kinetics equation was da/dt= 6.35×1012(1-?)[-ln(1-?)]-3 exp(-2.4×104/T).In the third stage,the decomposition of organic groups was intensive.the products of benzene derivatives was increased.Its thermal degradation mechanism was nucleation and growth process and its reaction order was 4.Its thermal decomposition kinetics equation was d?/dt=7.0 × 1017(1-?)[-ln(1-?)]-3 exp(-3.57×104/T).From the above,a series of different vinylphenylpolysilsesquioxane were synthesized by kinds of methods.We can control the molecular weight,the vinyl content and the structure of products by changing reaction condition and the molar ratio of raw.We also lucubrated the structure,thermal decomposition kinetics and thermal decomposition mechanism of different vinphenylpolysilsesquioxane.All of these have important guiding significance in both preparation and application of vinylphenylpolysilsesquioxane.