Fabrication method of TiO 2–SiO 2 hybrid capsules and their UV-protective property

Abstract

This article presents a novel miniemulsion-combined sol–gel process to fabricate TiO 2–SiO 2 hybrid capsules. In this approach, the oil phase composed of acetylacetone (Acac) modified titanium (IV) butoxide (TBT), dimethyl benzene (DB) and hexadecane (HD) is confined in the miniemulsion droplet microreactors with the aid of a cationic emulsifier hexadecyltrimethylammonium bromide (CTAB). Then, a silica layer was coated onto the miniemulsion droplets by the co-condensation of amino-silane and tetraethyl silicate (TEOS). At the same time, TBT in the miniemulsion droplets diffused to the O/W interface and then initiated the sol–gel reaction, hence TiO 2–SiO 2 hybrid shell with TiO 2 colloids loading inside formed. TEM, FTIR, EDX and XPS indicated that TiO 2–SiO 2 hybrids possess hollow-like structure, with small titania colloids loaded in the titania/silica hybrid shells. Some influencing parameters, such as the concentrations of TBT in the oil droplet, the content of amino-silane in the silica precursor, on the morphology of the TiO 2–SiO 2 hybrid capsules were investigated. UV–vis spectra and dye degradation experiments showed that the polyurethane films doped with these hybrid colloids had a very good UV-protective property.