Anchoring Of Photo-initiator Onto Nanometer Silica Particles Surface And The Photo-grafting Polymerization Of Vinyl Monomer

In this paper, the anchoring of photoinitiator onto the surface of nano-silicaparticles and photo-grafting polymerization of vinyl monomer initiated by modifiedparticles under UV irradiation have been investigated and the change of the nano-silica particles before and after photo-grafting have been characterized by FTIR,TGA/TA, SEM and TEM.The nano-silica surface was modified by TDI and thionyl chloride, and then thephoto-sensitive Irgacure2959 was anchored onto the surface of nano-silica particles.The evidence of the surface initiator was confirmed by FTIR, SEM, TGA/TA and UVabsorption spectrum. The SEM technique showed that the surface appearancechanged little when the particles were modified by thionyl chloride, but changed a lotby the TDI modified particles. The initiator contents were 47 mg/g and 37 mg/grespectively when the particles were modified by thionyl chloride and TDI. The UVabsorption spectrum showed that all the two particles could absorb UV.The organic/inorganic hybrid nano-silica particles were prepared by solutionpolymerization of MMA monomer initiated by Silica-C1-2959 and Silica-TDI-2959under UV irradiation. The change of monomer conversion, grafting ratio and graftingefficiency ratio, and the performances of two particles were investigated. The resultsshowed that the grafting ratio could reach to 300% after reaction for 3 h when usedSilica-TDI-2959 as an initiator, and the grafting density was higher. TGA resultsshowed that the thermostability of the MMA homopolymers was improved thanwithout the photo-grafting. SEM and TEM results approved that the particles havenanometer size and the diameter of the particles increased after the photo-grafting. The PMAA-g-Silica and the PAM-g-Silica particles were synthesized by thephoto-grafting polymerization under UV irradiation, the Silica-TDI-2959, MAA andAM were used as a photosensitive particles and a monomer respectively. The graftingratio of PMAA increased rapidly according to irradiation time, and could achieved200% after irradiation for 60 min; the grafting ratio of PAM increased a little andmaintain to about 40%. TGA and FTIR results afforded evidence of the graftedpolymer. SEM photograph showed that the morphological feature of the particleschanged a lot after grafted PMAA and PAM.