Synthesis Of Hydroxyl-Containing POSS And Thermal Properties Of Its Modified Silicone Resin

Polyhedral oligomeric silsesquioxane?POSS?has received extensive attention due to its organic-inorganic nanocage particle structure.POSS has excellent dielectric properties,heat resistance,mechanical properties,and good compatibility with polymers.It is commonly modified into polymers,including silicone materials.However,the problems of controlling accurate cage formation,low synthesis yield,long synthesis cycle and high synthesis cost are common in the synthesis process of POSS.This paper mainly discusses the synthesis of trisilanolphenyl POSS and the modification of POSS in methylphenyl silicone resin.The effects of reaction temperature and time on the synthesis of trisilanol-phenyl POSS are studied.The effects of POSS on the structure and heat resistance of methylphenyl silicone resin are also studied.In this artical,a scheme for the low temperature synthesis of trisilanolphenyl POSS is proposed.The reaction temperature,reaction time at high temperature and the effect of segmented dropping monomer on the synthesis of POSS are discussed.It is found that the synthesis of trisilanolphenyl POSS is more favorable at low temperatures.In the POSS synthesis system at high temperature,the silane monomer formed a stable T₄ and T₆structure which is difficult to continue to be caged,and the additional monomer can not successfully synthesize the trisilanol-phenyl POSS.The structure of the product in the POSS synthesis is verified by MS,²⁹Si NMR,FTIR and GPC.Based on the above synthesis,POSS is introduced into the methylphenyl silicone resin,wherein the trisilanolphenyl POSS can be directly applied to the hydroxy-terminated silicone resin due to its highly active Si-OH group.This paper synthesizes POSS/0806 methylphenyl silicone resin?American Dow Corning Company,abbreviated as 0806 resin?modified resin,and discusses different kinds of POSS?octasilicate hydroxy POSS,octahydric hydroxyl POSS,trisilanolphenyl POSS?,different content of POSS modified 0806 silicone resin,in which 5 mass%trisilanolphenyl POSS modified 0806silicone resin has a T_?d,5%?of up to 539.00^°C,which is increased by 32.96^°C.At the same time,a trisilanolphenyl POSS/synthetic methylphenyl silicone resin modified resin is synthesized.The influence of the way of POSS addition is discussed.The addition of POSS in the synthesis of silicone resin is more beneficial to the modification of resin.The modification of silicone resin with different content of trisilanolphenyl POSS is discussed.Among them,5 mass%trisilanolphenyl POSS had the best modification effect on the resin,T_?d,5%?is 543.24^°C,which is increased by46.95^°C.The modified resin is tested by FTIR,SEM and GPC to study the structure,molecular weight and dispersibility of the modified resin.Finally,the decomposition activation energy of pure resin and 5 mass%POSS modified self-synthesized methyl phenyl silicone resin is solved by thermal decomposition kinetics.The activation energy of the high temperature stage of resin decomposition increased by 44.7%?53.34 kJ/mol?.