Synthesis And Properties Of Organosilicon Elastomer Via Aza-Michael Reaction

Silicone elastomers are widely used as safe and durable materials for electronic and electrical,building materials,domestic and industrial applications because of their resistance to weathering,high and low temperatures,radiation,and so on.Traditional silicones are normally thermoset materials,which are prepared by three main methods:(1)Pt-catalyzed hydrosilylation between Si-H and vinyl groups;(2)condensation reaction between Si-OR and-OH;(3)free-radical cross-linking.However,these methods have some drawbacks,including the high costs of the catalysts,side reactions and cumbersome steps.Therefore,it is particularly important to explore a simple and efficient method to prepare silicone elastomers and expand their applications.Aza-Michael addition reaction is an important synthetic reaction,which amine compounds react with ?,? unsaturated alkenes.The reaction process has many advantage that catalyst-free,high efficient,no-side products.In this paper,reversible silicone elastomers were prepared based on the reaction of Aza-Michael addition.Photo-initiating and thermo-reversible silicone elastomers were synthesized via Aza-Michael addition reaction.Firstly,anthracene containing polysiloxane was prepared from polypropylmethylsiloxane and anthracene monomer through Aza-Michael addition reaction.Anthracene group can undergo[4+4]cyclo-addition reaction under UV light,thus a crosslinking network is constructed.The crosslinking network can be destroyed when heated,thus endowing the elastomer with reversible properties.In addition,the sunlight instead of the UV light initiated the cyclo-addition reaction,which is a green and environmentally friendly way,compared with the traditional UV light-induced ring addition reaction.The prepared films are fast and convenient for cross-linking,and the films can be prepared on any surface.The UV-LED beads was infiltrated into the uncrosslinked anthracene containing polysiloxane pre-polymer solution and obtained the colored UV-LED light beads after curing.The simple method of "in situ" crosslinking is efficient and does not require high energy consumption.It shows important application value in light-emitting devices.Silicone elastomers with anthracene based polysiloxane as the concentrated crosslinking agent were prepared by "one-pot" process.Due to the dimerization of anthracene with UV light,and the depolymerization was completed by heating.anthracene is connected to poly(amyl methyl siloxane)by the Aza-Michael addition reaction,and the synthetic polysiloxane with different amino content is used.The elastomer with best mechanical properties and reversible is obtained by controlling the proportion of two kinds of polysiloxane and anthracene.Silicon elastomers with self-healing properties were prepared by Aza-Michael addition reaction.The 4-(4,4,5,5-tetramethyl-1,3,2-boroxyl)benzyl acrylate was combined with poly(aminopropyl methyl siloxane),and the silicon elastomer containing boron was prepared by the use of B-N bond.The prepared materials not only have self-healing properties,but also can be reused.It is found that the elastomer is insoluble in trichloromethane,dichloromethane and toluene,but can be dissolved in the solvent of butyl amine;when the solvent is removed,the elastomer can be obtained again.In addition,the elastomer prepared has better self-healing ability.Compared with traditional self-repairing materials,the material not only has simple synthesis process,but also realizes spontaneous self-repair without any external energy.