COMPOSITE OF SIO2 AND HYDROGEL HAVING MICROPHASE-SEPARATED STRUCTURE - PHYSICAL-PROPERTIES DEPENDENCE ON PH

Organic-inorganic composite gel was prepared by using PEG-modified ure thane acrylate (PMUA) gel and tetraethoxysilane (TEOS). PMUA gel was p repared by the phase-inversion emulsion polymerization of PMUA emulsio n. The gelation of PMUA emulsion using this method enables PMUA gel to swell with H2O, TEOS, and ethanol. Hydrolysis and condensation reacti on rates of the sol-gel process are strongly influenced by the pH cont rolled by catalysts such as HCl and NH4OH. Additionally, the morpholog y on the cross section of composite and the amount of silica ingredien t incorporated into the composite gel were dependent on solvent, the m olar ratio of H2O to TEOS, as well as the pH value. As the silica cont ent increased, due to hydrogen bonds interacting between PMUA gel and SiO2, particles, the tensile strength of composites considerably incre ased, whereas the elongation at break decreased. The incorporation of silica ingredient in PMUA gel/silica composites was verified with FTIR /ATR and SEM. The amount of the silica component in the composite was indirectly investigated by using TGA thermal analysis.