Synthesis And Properties Of Organosilicon Polymers Containing Perfluorocyclobutane Rings

Fluorosilicone polymer is a kind of polymer containing fluorine groups and siloxane structure by covalent bond.It has not only the excellent properties of polysiloxane,such as temperature resistance and weather resistance,but also the advantages of solvent resistance of fluoropolymer.Therefore,it has been widely used in the fields of aerospace,chemical,paint,textile etc..Usually fluorosilicone polymer means fluorosiloxane with-Si-O-Si-as the backbone and fluoroalkyl as the side chain.Due to the strong electron withdrawing effect of fluorine atoms,the effective positive charge of Si atoms is increased,so the thermal stability of polymer is reduced.In order to meet the requirements of high temperature resistance and solvent resistance,perfluorocyclobutyl-aryl-ether structure(PFCB)is introduced to the backbone of polysiloxane.Starting from p-bromophenol and 1,2-dibromotetrafluoroethane as raw materials,[4-(1,2,2,-trifluorovinyloxy)phenyl]dimethylsilane was synthesized through three steps reactions.ATR-FTIR,NMR had been used to characterize the structure and purity of each intermediate.Then we synthesis four new kinds of trifluorovinyl aryl ether compounds by Rubinsztajn reaction and hydrosilation reaction.Three kinds of highly cross-linked polymers were prepared by the[2? + 2?]thermal cyclization reaction of the trifluorovinyl aryl ether.After confirming the structure of the polymers,the thermal stability,solvent resistance,dielectric property,transparency and water absorption were characterized.The results showed that these polymers have excellent thermal stability,high transmittance,low dielectric constant and low water absorption,and they can be used as high temperature resistant optical components or low dielectric materials.In the meantime,using trifluorovinyl aryl ether compounds as crosslinking agent,HTV fluorosilicone rubber were prepared by the cyclization reaction of the trifluorovinyl.The results showed that the PFCB structure gives the material excellent solvent resistance,the rigid group gives the material excellent thermal stability.