Surface-modification Of Silica Carbide Nanoparticles Via Reverse Atom Transfer Radical Polymerization

Nano-SiC particles are easily reunited for its ultra-fine-grained and macro surface energy.Surface modification and coating of nano materials for the improvement of the dispersion property and surface property have being become the critical technique in the preparation and application of nano particles. The surface-initiated reverse atoms transfer radical polymerization (RATRP) a new surface modification technique of nano material which is well-proved to dispersion property of nano particles.A new surface modification of nano-SiC in water by RATRP was designed and studied according to polymerization mechanism of RATRP and stability mechanism of nano-SiC dispersion in water.Firstly, The introduction of active group for RATRP and optimum conditions with KH-570 to nano-SiC were discussed. Surface- initiated RATRP modification of nano-SiC was investigated with catalysts of CuCl2/O-phen and FeCl3/PPh3 . Activation index zete potential and turbidity were used as index of modification effect of nano-SiC particles. Chemical composition, thermal properties, particle size, dispersion state of nano-SiC after modification were characterized by IR, TG-DTA, XRD, TEM, FESEM and so on. Finally the modification effect by RATRP and conventional radical polymerization was compared .The results show that the good introduction of the active groups for RATRP was–C=C- on the surface of nano-SiC though coupling reaction of KH-570 after hydrolysis. The better coupling condition under KH-570/H2O 1:9(molar ratio) , pH 6.2 toluene as solvent and coupling reaction time 7h. The optional process conditions with RATRP modification of nano-SiC were CuCl2/O-phen was acted as catalytic system, AM as monomer and AM/KPS=100, AM/CuCl2=150, AM/O-phen=100, water as solvent. Compared with conventional radical polymerization that RATRP had better effect for formation of a large area, controlled thickness, union PAM film covered on the surface of nano-SiC was formed through physical and chemical cross-linking functions to produce electrostatic and steric stabilization mechanism.