SYNTHESIS OF CATIONIC THERMO-RESPONSIVE MICROGELS AND THEIR APPLICATION FOR BIOMIMETIC MINERALIZATION OF SILICA

Cationic thermo-responsive microgels of P (NIPAM-co-DMC) were synthesized by copolymerizing mononers of N-isopropylacrylamide (NIPAM) and 2-methylacryloyloxyethyltrimethyl ammonium chloride (DMC) in the presence of a crosslinker N, N'-methylene-bis-acrylamide (MBA) by soap-free emusion polymerization. TEM observation indicates that the average diameter of copolymer microgels is about 200 nm. The lower critical solution temperature (LCST) of the prepared microgel is estimated to be about 34 degrees C by both DLS and H-1-NMR measurements. This cationic microgel was further used as a colloidal template for biomimetic mineralization of silica. The silica deposition was performed by simply stirring a mixture of aquous solution of microgel and TMOS at room temperature and neutral pH. The combination of FTIR, TEM, H-1-NMR and TGA characterizations indicated that silica mainly deposited on the shell region of microgels. Moreover, we observed that hybrid nanoparticles with shringaged shape were formed when the silicification was performed at 40 degrees C