Synthesis Of A New Type Of Silacyclobutene Monomer And Properties Of Polymers

In recent years,high performance and low dielectric materials have attracted much attention in the fields of microelectronics packaging,high frequency circuit board,radar wave transmission and so on.For low dielectric materials,on the one hand to suppress the need to reduce the dielectric response rate of the chemical structure of polarization,but on the other hand,the need to improve the material cohesive energy to improve the mechanical strength,thus realizing the great conflict between the low dielectric constant and high mechanical strength.The formation of cross-linked network polymer structure is an important means to balance this contradiction,but the research on the crosslinking network structure is not thorough,especially for the design of fine structure and its influence on the performance is still insufficient.Benzocyclobutene(BCB)and silicon heterocyclic butane is one of the few reaction groups reported without catalyst,no release of small molecules with low polarity,but the two groups have different features,BCB group formed after the reaction of benzene and eight membered ring is a rigid structure,and silicon heterocyclic butene open loop forming carbon silane straight chain,belong to flexible structure.Based on this,this paper designs three kinds of crosslinking structure were synthesized,including the main side chain and main chain rigid flexible / rigid main chain and side chain side chain rigid / flexible structure,in-depth comparison and discussion of mechanical properties,low-dielectric and thermal properties,bring the fine structure of the crosslinking effect,to provide ideas and feasible scheme for the realization of the new the balance of low dielectric constant and high mechanical strength.Benzocyclobutene-introduced poly(silmethylene)s(PBCS)was synthesized by ring-opening copolymerization of benzocyclobutene(BCB)functionalized disilacyclobutene(DSCB)with phenyldisilacyclobutene.The incorporation ratio of BCB was tailored by changing feeding ratio of1,3-dimethyl-1,3-dibenzocyclobutene-1,3-disilacyclobutane(DMDBDC)and1,3-dimethyl-1,3-diphenyl-1,3-disilacyclobutane(DMDPDC),thus enabling the control of ultimate properties of cured resins.With increasing the incorporation ratiosof BCB from 9.5 to 28.9 mol%,T5% of cured resins is improved from 404 to 462 oC,while the dielectric constant is decreased from 2.59 to 2.41 at 10 MHz.On the basis of the photoactive silaycyclobutene moiety,a new monomer,1-methyl-1-(4-vinylphenyl)silacyclobutane(1-MVPSCB),was synthesized and demonstrated successful to conduct atom transfer radical polymerization(ATRP).Subsequently,the copolymerization of 1-MVPSCB with 4-vinylbenzocyclobutene(4-VBCB)and styrene produced a kind of benzocyclobutene/silacyclobutane double-crosslinked polymer(BS-DCP)with controlled benzocyclobutene/silacyclobutane ratios and low polydispersity index.Owing to the UV/thermally dual cross-linked structure,benzocyclobutene/silacyclobutane double-crosslinked polymer BS-DCP possesses photapatternability,high dimensional stability,excellent thermal stability and low dielectric constant(2.37 at 10 MHz).The mechanical properties of the polymers was tailored by changing feeding ratio of 1,3-dimethyl-1,3-dibenzocyclobutene-1,3-disilacyclobutane(DMDBDC)and benzocyclobutene/silacyclobutane double-crosslinked polymer.The silacyclobutane of BS-DCP and the disilacyclobutane(DDSCB)of DMDBDC could take ring-opening reaction in the presence of Pt.Nano-indentation results show that with the increase of the molar ratio of DMDBDC,the mechanical properties of the composites are improved boviously.When the content of DMDBDC reaches 30%,the corresponding modulus is 8.01 GPa,meanwhile,the dielectric constant is reduced to2.35 at 10 MHz.