Studies On Grafting Polymerization Of Glycidyl Methacrylate On Silica Nanoparticles By ATRP Method

Atom transfer radical polymerization(ATRP) and grafing polymer onto the surface ofinorganic particles are both much attractive research areas in recent years. They haveimprotant theory significance and practical application value. The aim of this article isgrafting polyglycidyl methacrylate(PGMA) onto the surface of silica nanoparticles by ATRP,and investigating the rules of homopolymerization and grafting polymerization of glycidylmethacrylate(GMA) at ambient temperature.ATRP of GMA was carried out by using ethyl 2-bromopropionate (BRA) as initiator andCuBr/bpy as catalyst system in solution polymerization system at ambient temperature, andhomopolymer PGMA with narrow polydispersity was obtained. The polymer PGMA wascharacterized, and the living polymerization was confirmed by GPC, FTIR and 1HNMR. Theeffects of the ratio of monomer concentration to initiator concentration on the rate and controlof the polymerization were examined, and the effect of the polarity of solvents on the controlof the polymerization was also investigated. The dynamics study was performed, and theapparent activity energy of ATRP for GMA was determined. The experimental results showthat the controlled polymerization of GMA by ATRP at ambient temperature can be realizedfavorably by using cyclohexanone as solvent, not only the reaction rate is properly fast, butalso polymers have narrow molecular weight distribution. When anisole is used as solvent,which polarity is weaker than cyclohexanone, the polymerization rate is decreased obviously.The concentration ratio of monomer to initiator has influence on the polymerization ratedistinctly, and the smaller is the ratio, the faster is the rate, additionally, the control of thepolymerization becomes poorer. The apparent activation energy of ATRP for GMA by usingBRA/CuBr/bpy as initiation –catalysis system was determined to be 61.4kJ/mol.Via the reaction between the hydroxyl on the surface of activated silica nanoparticles and2-bromoisobutyryl bromine(BSB), the silica nanoparticles which contain initial radical on thesurface(BSB-SiO₂) were obtained. Grafting GMA onto the surface of BSB-silicananoparticles was carried out by using cyclohexanone as the solvent and CuBr/bpy as catalystsystem in solution polymerization system in the presence of the "sacrificial" free initiator ofBRA at ambient temperature. The polymerization producer was characterized, and the livinggrafting polymerization was confirmed by FTIR, TGA and GPC et al. The researchful resultsindicated that the polymerization exhibited the first-order kinetic rule. The grafting productPGMA has a narrow molecular weight distribution. Both relations between the graftingamount and the monomer conversion, and between the molecular weight and conversion arelinear relation. The grafting density(the number of graft chain per unit area) was constantduring the course of polymerization. The functional monomer GMA could been grafted ontothe surface of silica nanoparticles by ATRP successfully.