Synthesis And Characterization Of The Self-healing Monomers For Polymer Composites

Based on the "implant" self-healing system developed by S. R. White et. al, we proposed a novel self-healing polymer composite system. In our system, healing is accomplished by incorporating a microencapsulated healing agent dispersed in matrix and by a supported catalyst on particle or fiber fillers. The catalyst fixed on supported platinum catalyst which can catalyze hydrosilylation reaction quickly at ambient atmosphere. The healing agent could be a kind of oligo-organosiloxane containing both Si-H bonds and Si-vinyl bonds.In this system, synthesis of vinyl branched oligo-organosiloxane takes a crucialplace.α,ω-dichlorine-terminated vinyl branched siloxane(?)(â… ) and(?)(â…¢) were synthesized via ring-opening of two kinds of cyclosiloxane,hexamethyl-cyclotrisiloxane (D₃) and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (D₄^v₁), in the presence of vinylmethydichlorosilane (MeViSiCl₂).Then the healing agents (?) ,n=3, 4,5(â…¡)and (?), n=4, 5, 6 (â…£),which contain both vinyl group and double Si-H bonds, were prepared by reducing the oligomers by lithium aluminum tetrahydride.Polymerization of the two healing agentsâ…¡andâ…£catalyzed by Karstedt catalyst was investigated. The results show that the healing agents can be polymerized by hydrosilylation reaction. The intrinsic viscosity of polymerized products P1 and P2 was measured with Ubbelohde viscometer. Compared with the two healing agents, the intrinsic viscosity of P1 and P2 both increase. Finally, P2 turned into gel while P1 didn't.