Nanosized-hybrid colloids of poly(acrylic acid)/titania prepared via in situ sol–gel reaction

Nanosize-hybrid colloids of poly(acrylic acid) (PAA)–titania (TiO2) were synthesized and characterized. The methods of preparation were based on an in situ sol–gel technique using titanium isopropoxide as precursor in the butanol solution of PAA. Two synthetic pathways to the fabrication of hybrids were utilized, involving adding titanium precursor after or before the PAA was fully dissolved. Different phenomena of phase separation and gelation were observed in these two synthetic pathways, but both yielded stable colloidal solutions after further heating. Various mole ratios of PAA/titanium isopropoxide/water and synthetic routes were employed to examine the interaction between PAA and titania. The hybrid materials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electronic microscopy (SEM). The FTIR results verified the successful formation of the chelation bond between PAA and titania. TGA demonstrated that the thermal stability of pure PAA was improved by chelating with titania. DSC showed the PAA strongly interacted with titania, leading to the confinement of the thermal motion of PAA chains. The SEM results revealed that the preparation method and the mole ratios of PAA/titanium precursor/water considerably affected the size and shape of PAA–titania hybrid aggregates, and the extent of aggregation.