Study On The Synthesis Of Functionalized Polysiloxane Catalyzed By Cyclic Phosphazene Base

Organic silicon elastomers play an important role in industrial production and daily life due to their excellent thermal and radiation stability,high permeability,low dielectric constant,damping,electrical insulation,and excellent biocompatibility.Although silicone elastomers have a wide range of applications,there are still shortcomings in the research on silicone films.Currently,the silicone film products that have been applied are mainly made of polydimethylsiloxane（PDMS）based polymers.Long term use in harsh environments can lead to a decline in product performance or even failure.Therefore,the aging resistance,damping,radiation resistance,and high and low temperature resistance of the materials themselves urgently need to be improved.Introducing phenyl groups into the PDMS backbone can effectively inhibit polymer crystallization and enhance the aging and damping properties of the polymer.Therefore,in this paper,functional polysiloxane was synthesized by ring opening copolymerization（ROCP）of D₄（tetramethylcyclotetrasiloxane）,D₄^8Ph（octaphenylcyclotetrasiloxane）and D₄^Vi（tetramethyltetravinylcyclotetrasiloxane）catalyzed by organic catalyst CTPB,and organosilicon films and silicone rubber were prepared by hot pressing and UV curing The impact of aging resistance and damping performance.The main work is divided into the following three parts:1.Using D₄ and D₄^Vi as monomers,CTPB as catalyst,benzyl alcohol as initiator,PMVS with different vinyl content on the side groups was synthesized through ring opening copolymerization（ROCP）;Using D₄,D₄^8Ph,and D₄^Vi as monomers,the molar ratio of D₄^Vi in the monomers was maintained at l mol%.The feed ratio of D₄ and D₄^8Phmonomers was changed from 98/1 to 69/30,and PMPVS with different diphenyl content on the side groups was synthesized through ring opening copolymerization（ROCP）;Organic silicon thin films were prepared by hot pressing to obtain transparent and uniform organic silicon thin films.The silicone film was characterized by DSC,TGA,SEM and FTIR,and the tensile test and thermal oxygen aging test were carried out on the silicone film to explore the influence of the content and type of vulcanizing agent,silica,vinyl content,diphenyl content on the mechanical properties of silicone film,as well as the influence on the aging resistance and thermal stability of silicone film.The experimental results show that the optimal tensile strength and elongation at break of the prepared silicone film are 7.7 MPa and 1043%,respectively;The organosilicon film containing diphenylsiloxane has better aging resistance and thermal stability.2.Using D₄ and D₄^8Ph as monomers,CTPB as catalyst,H₂O as initiator,and a small amount of tetramethyldivinyldisiloxane as blocking agent,PDPS with different diphenyl content on the side groups was synthesized through ROCP in a reactor.Characterization of the prepared silicone rubber using DMA to explore its mechanical and damping properties.The experimental results show that the optimal tensile strength of the prepared silicone rubber is 10.4 MPa,and the elongation at break is 419%.With the increase of diphenyl content,the effective damping temperature range of the silicone rubber gradually increases and widens（the temperature range increases from 20.0℃ to 50 ℃）...