Study On The Synthesis And Properties Of Polyborosiloxane

Cycle-borasiloxanes and polyborosiloxanes are the more specialized branches in the field of organicsilicones,Since the molecular backbone is not completely connected with Si-O bonds,the main chain is also doped with Si-O-B bonds.So it has its own unique physical and chemical properties compared with ordinary cyclosiloxanes and polysiloxanes.Since 1960,Vale produced the world's first polyborosiloxane through the reaction of dimethyldichlorosilane and boric acid.Due to the unique high-temperature resistance and oxidation resistance properties,polyborosiloxane showing its wide range of applications.Attracting the attention of scholars,and thus become a hot research.But because of its intolerant hydrolysis characteristics,making it cannot be widely used in real life.Cycle-borasiloxane have also been considered the best monomer for the synthesis of polyborosiloxanes,also attracted the attention of countless scholars,Although it was subsequently confirmed that the polyborosiloxane could not be obtained by using ring-opening polymerization of cycloborasiloxane and no one is willing to study the chemical reaction mechanism.So this paper will be from the following aspects to introduce our work:1?Cycle-borasiloxanes were synthesized through a two-step reaction.First,the Phenylboronic acid was reacted with excess amount of dimethyldichlorosilane and thus Si-Cl teminated borasiloxanes were obtained.Subsequently,Si-Cl teminated borasiloxane was used to react with metal oxide and expected products were obtained.The effects of reaction conditions on the reaction were investigated.And the chemical reaction mechanism of cycle-borasiloxane under alkali catalysis was elucidated by experiments.2? Polyborosiloxanes were prepared by the hydrosilylation and the Piers-Rubinsztajn condensation.By changing the substituents of the monomers,the length of the segments and the proportion of boron atoms in the polymer.The relationship between these variables and the hydrolysis resistance and thermodynamic properties of polyborosiloxane was studied.The relationship between the structure and viscosity and molecular weight of the polyborosiloxane is also described.3?Through the synthesis of polysiloxane which contain the vinyl structure.And then it was added to the silicone rubber as an additive to prepare the boron-containing silicone rubber.The relationship between the thermodynamic and mechanical properties of boron-containing silicone rubber was studied.