Research Of Nanometer ZnO/TiO₂ As A Broad Spectrum Sunscreen

Nanometer ZnO/TiO₂ as broad spectrum sunscreen has been gained combining the strongpoint of nanometer ZnO with nanometer TiO₂. The ZnO/TiO₂ composite particles were prepared by sol-gel with Ti(SO4)2 and Zn(AC)2 as raw materials .The surface structure of samples was characterized by IR/TEM/XRD/UV-vis .The results show that the diameter of the composite particles is 50nm-100nm by controlling the different reaction conditions and they have the structure of TiO₂ as core and ZnO as shell .From the results of the characterization we discussed the formative mechanism of the ZnO/TiO₂ composite particle . Because of the strong polarity the nanometer particles agglomerate easily in the un-polarity solutions. we attempted to modify the composite particles with organosiloxane:â‘ Silane coupling agents(KH-570)and methyl methacrylate(MMA) were initiated to polymerize at the surface of nanometer ZnO/TiO₂ composite particles utilizing the un-saturation bonds and hydroxyl in the surface of ZnO/TiO₂ composite particles and the "bridge"actions of the silane coupling agents. â‘¡Cyclomethicones(D4) modified the ZnO/TiO₂ composite particles via emulsion polymerization .The analysis of FT-IR indicates that there are some graft polymer at the ZnO/TiO₂ composite particles .The surface properties of modified composite particles were studied by dispersability and penetration, the results appear that the modification of composite particles can improve both the lipophilicity and dispersion properties .The result of UV-vis absorption spectroscopy indicates the composite particles have elegant ultraviolet absorption, the photocatalytic experiment reveals that the photocatalysis of the modified particles decrease badly, especially the photocatalysis for D4 modified composite particles can be shielded almost completely. Introduced the composite particles into the cosmetic, we have achieved the fine stability. We compared the ultraviolet absorption of sun block (KML and DL) made by ourselves with the Avon's day block SPF30(YFSPF30)and Mininurse's SPF15(XFSPF15),the results display the ultraviolet absorption of KML is as much as the DL .During 280nm-355.2595nm wavelength the ultraviolet absorption of DL excels to XFSPF15,and less than YFSPF30; In the scope of 355.2595nm-400nm wavelength the ultraviolet absorption of DL is stronger greatly than XFSPF15 and YFSPF30.In a conclusion the effect of the ZnO/TiO2 composite particles on ultraviolet prevention in the whole ultraviolet wavelength is excellent and it is also safe.