Synthesis And Properties Of Novel Polysiloxane Materials

In this paper,monofunctionalized POSS was introduced into the side chain of Polymethylvinylpolysiloxane by chemical bonding method,and a soluble,meltable thermoplastic silicone polymer was prepared by using a POSS-specific cage-type rigid structure.A series of properties of the material were studied.The specific work is as follows:(1)Synthesizing linear Polymethylvinylpolysiloxanes with different molecular weight and similar to vinyl content,and linear Polymethylvinylpolysiloxanes with different vinyl content and approximate molecular weight,the specific vinyl content was determined by iodometric method.The heptaphenyl monohydrogen POSS was synthesized by a two-step method,and all the above materials were characterized by Nh4R and FT-IR.(2)Heptaphenyl monohydrogen POSS(Si-H POSS),as bulky siloxane side group,was grafted onto the linear polysiloxane backbone via hydrosilylation,tailoring the properties of the polymer.The effects of the change of POSS content on the thermal properties,crystallization properties and glass transition temperature of the materials were studied.The results show that the addition of POSS significantly improves the thermal stability of the polysiloxane chain(the initial decomposition temperature and residual rate increase significantly),and the glass transition temperature increases with the increase of POSS grafting content.(3)Mercaptopropyl Isobutyl POSS(MIPOSS),as bulky siloxane side group,was grafted onto the linear polysiloxane backbone via thiol-ene click reaction,tailoring the properties of the polymer.The effects of POSS loading and PMVS chain molecular weight change on thermal properties,rheological properties,crystallization properties,glass transition temperature and surface morphology of thermoplastics were investigated.The results show that we have successfully prepared thermoplastic silicone materials,the glass transition temperature increases with the increase of POSS content in the material,and has no relationship witih the molecular weight change of PMVS chain.At the same time,POSS can be uniformly dispersed in the material,and no crystallization phenomenon caused by self-aggregation of POSS is found.