Precipitation of multilayered core-shell TiO2 composite nanoparticles ontopolymer layers

A composite film of titanium dioxide (TiO2) nanoparticles and hydrolyzed st yrene-maleic anhydride alternating copolymer (HSMA) was obtained on a subst rate when a TiCl4 solution was heated at 80 degreesC with a spin-cast thin HSMA film present in the solution. The composite film was characterized wit h x-ray photoelectron spectroscopy and transmission electron microscopy. Re sults revealed that TiO2 nanoparticles discretely dispersed on the poly-mer layer, and they were dominantly rutile phase, of a spherical shape and 18- 20 nm in diameter. In contrast, mainly amorphous TiO2 powders were obtained from the identical TiCl4 solution by drying the solution with the absence of the HSMA film. The TiO2 nanoparticles deposited on the polymer layer wer e regarded to contain polymer chains, rind a multilayered core-shell model was suggested for the formation of these composite nanoparticles. It is reg arded that the core of a composite particle consisted of an anatase-phase T iO2 colloidal nanoparticle, while the shell layer was made of rutile-phase TiO2/polymer multilayers; the composite particles formed by a layer-by-laye r self-assembly of TiO2 and polymer layers analogous to biomineralization, where the polymer promoted the crystallization of rutile-phase TiO2 when Ti O2 deposited from solution.