Organic-inorganic polymer hybrids using polyoxazoline initiated by functionalized silsesquioxane

New hybrid polyoxazolines (CubePOZO) were synthesized by ring-opening polymerization of 2-methyl-2-oxazoline initiated by functionalized polyhedral oligomeric silsesquioxane (POSS) with various feed ratios. The hybrid micelles derived from CubePOZO with both seven hydrophobic cyclopentyl groups of POSS and polyoxazoline (POZO) as a hydrophilic segment were prepared in an aqueous phase. Compared to POZO initiated by cyclohexyl iodide or methyl p-toluenesulfonate, increased hydrophobicity caused by the structure of POSS in CubePOZO played a major role in the micelle formation. This depended on the amount of POSS incorporated into the POZO. The CubePOZO100 and CubePOZO200 formed micelles in an aqueous phase with critical micelle concentrations (cmc) of 55 and 100 mg/L, respectively. Transparent polymer hybrids, homogeneous dispersion of hydrophobic POSS bonded covalently to POZO in the silica gel matrix at the molecular level, were obtained through hydrogen-bonding interaction between CubePOZO and silica gel. The obtained polymer hybrids from CubePOZO showed excellent solvent resistance, similar to that of polymer hybrids having an interpenetrating polymer network structure. It was concluded that the solvent-resistant property came from the size of POSS and the hydrophobic interaction between the POSS in the silica gel matrix. In addition, thermal stability of the polymer hybrids from CubePOZO was much increased compared to that of the polymer hybrids from homoPCZO and POSS.