Synthesis Of Novel Carborane Derivatives And Graft Modification Application On Silk Fabrics

In this dissertation,a series of novel carborane derivatives were synthesized by the addition reactions of alkynyl compounds with boron cage acetonitrile complexes.Carborane-based monomers were applied on silk fabrics modification by graft copolymerization.The modification provided excellent thermal stability and flame retardancy because of the introduction of poly(carborane)branched chains.The main discussions were as followings:(1)Using hydroxyethyl methacrylate(HEMA),propargyl bromide and boron cage acetonitrile complexes as raw materials,1-methacryloxyethyloxamethyl carborane(PMAC)was synthesized as intermediate.Then treating with chlorodimethylsilane and chlorotrimethylsilane by reduction and substitution reactions,the siloxane chain was successfully introduced into PMAC.And the target monomer named 1-methacryloxyethyloxamethyl-2-(1,1,1,3,3-pentamethyldisiloxanyl)carborane(PMASC)was formed,which was then used to modify silk fabrics.Modified silk fabrics were tested by FT-IR,XRD and SEM.The thermal stability of silk was measured by TGA,DSC and MCC analysis as well.It could be observed that the silk fabrics with higher graft yields exhibited stronger heat-resistance.(2)The intermediate of 1-phenylacyloxyethyl carborane was prepared using 3-butyn-1-ol,benzoyl chloride and boron cage acetonitrile complexes as raw materials.After 1-phenylacyloxyethyl carborane was hydrolyzed and then esterified,hydroxyethyl carborane and 1-acryloyloxyethyl carborane were obtained respectively.The obtained carborane acrylate was emulsified and applied onto silk fabrics by graft copolymerization.FT-IR showed the evidence of the reaction between carborane acrylate and silk fabrics,and the thermal stability of silk fabrics were tested as well as the flame retardancy.The results indicated that the flame retardant properties of the modified silk fabrics had been improved.MCC analysis demonstrated that with the increase of the grafting ratio,the performance of the modified silk fabrics was identified to be more thermal stable because more carborane-based polymers were introduced onto the surface of silk fabrics.(3)The carborane acrylate monomer and phosphate containing methacrylate(PAM-200)monomer were blended and grafted onto silk fabrics via copolymerization method.This could introduce branched chains containing boron and phosphorus elements simultaneously into silk fibers.The graft copolymerization between these two monomers and silk were elucidated by FTIR,SEM and EDS.The shape of the silk fabrics treating according to the above method was kept after burning even if the silk had decomposed completely,and thus the holes and channels structure formed in the residual char skeleton.The reason for the formation of the skeleton was the carbonization of phosphorus and generating of boron oxide at high temperature.All these results suggested the formation of a protective layer,which insulated the oxygen and heat and enhanced the flame retardancy of the silk fabrics by graft modification.Comparing the above three different grafting methods,it could be found that the heat release rate of modified silk fabrics decreased obviously when grafted with the silicon-carborane containing acrylate monomer.Meanwhile,the char yields and LOI values increased.This indicated that the fire risk of the modified silk fabrics decreased when compared with that of the untreated silk fabrics.Unfortunately,the modified silk fabrics could not reach the requirement of the flame retardant fabrics standard,while the silk fabrics modified with phosphate methacrylate showed better flame retardancy.Furtherly,using 1-acryloyloxyethyl carborane and phosphate containing methacrylate as blended monomers,the treated silk fabrics could be obtained with excellent flame retardancy,whose LOI value had reached 29.8%.