Synthesis And Performances Study Of A Novel Silicone Adhesive

Silicone adhesives have been widely used in aviation,electronics,communications,construction,and other fields because of its radiation resistance,high and low-temperature resistance,solvent resistance,and so on.However,its weak adhesion to metal limits its application.In this paper,Nacetylcysteine(NAC),an amino acid substance,was introduced into the side chain of hydroxyl-terminated methyl vinyl polysiloxane to obtain the silicone adhesives that can be cured at room temperature and has strong adhesion to iron copper and aluminum.Then octa(trimethoxysilyl-4-sulfidehexyl)POSS(OTPOSS)and octaepoxycyclohexylethylPOSS(OEPOSS)were synthesized and used as curing agents to modify the silicone adhesives.A series of POSS modified silicone adhesives with strong adhesion to iron,copper,and aluminum was obtained.These are the main research contents of this paper.(1)Two different molecular weight hydroxyl-terminated methyl vinyl polysiloxanes were prepared by anionic polymerization method,and different proportions of NAC were grafted to the side chain of hydroxyl-terminated methyl vinyl polysiloxane through "thiol-ene" click chemistry.The results showed that the obtained adhesives had a certain degree of hydrophobicity and thermal stability,their hydrophobic angles were greater than 90°,and the initial thermal decomposition temperatures were above 200℃.The adhesion ability of the adhesives to iron was stronger than those of copper and also stronger than that of aluminum.Among them,PVMS-40%NAC-C had the best adhesive performance to iron,and the tensile shear strength of 40#Steel reached 7.76 MPa;PVMS-80%NAC-C had the best adhesive performance to copper,and the tensile shear strength to brass reached 4.96 MPa;PVMS1-40%NAC-C had the best adhesive performance to aluminum,and it had the best adhesive performance to aluminum alloy.The tensile shear strength reached 2.66 MPa.(2)The OTPOSS was synthesized by the "thiol-ene" addition reaction.The dielectric constant and hydrophobicity of the POSS-modified silicone adhesives were increased.The adhesion of iron and aluminum was improved.The tensile shear strength of 40#Steel was increased by 39.66%,and the tensile shear strength of aluminum alloy was increased by 244.60%。(3)The OEPOSS was synthesized by hydrolysis and condensation of trimethoxysilane.The dielectric constant and thermal stability of the OEPOSS modified silicone adhesives were increased.The adhesion of three kinds of metal was greatly improved.For 40#Steel,the maximum increase in tensile shear strength was 59.72%,and the maximum increase in tensile shear strength of brass was 43.84%;the maximum increase in tensile shear strength of aluminum alloy was 194.53%.