Organic-inorganic interactions in poly(trimethylene carbonate) – titania hybrids

Polycarbonate-titania hybrids were synthesized via sol-gel, starting from polyTMC and titanium isoproproxide in different ratios. PTMC with given chain length was obtained via ring opening polymerization. FT-IR spectra reveal the presence of Ti-O-C covalent bonds between organic and inorganic phases, their number increasing with increasing inorganic phase content. Solvent extractions show that hybrid soluble fraction contains low PTMC chains with isopropoxide ends, suggesting that Ti-O-C bond formation is mainly promoted by transesterification reactions of isopropanol onto the polymer chain, catalyzed by Ti compounds. Hybrid thermal properties reflect the combined effect of the decrease of PTMC molecular weight and of bond formation between PTMC and the inorganic network. Nanometric dimension of TiO2 domains, confirmed by AFM, provides optically transparent hybrids.