(6d) Benign Nano-Thin Film Composite Particles for Protection from Uva/Uvb - Rays

Authors: 
King, D. M., University of Colorado, Boulder
Hakim, L. F., University of Colorado
McCormick, J. A., University of Colorado
Zhan, G., University of Colorado
Gump, C., ALD NanoSolutions, Inc.
Buechler, K. J., ALD NanoSolutions, Inc.
George, S. M., Rensselaer Polytechnic Institute/University of Colorado at Boulder
Weimer, A. W., University of Colorado at Boulder


Composite TiO2/ZnO particles capped with an Al2O3 nanolayer have been designed and synthesized for the benign protection from UVA/UVB ? rays. Titania (TiO2) provides excellent protection against UVB ? rays. Zinc oxide (ZnO) protects against UVA-rays very efficiently. The manufacture of composite particles via novel Atomic Layer Deposition (ALD) thin film technology allows for the synthesis of composite particles with dual effectiveness. In the first aspect of this work, two ZnO/TiO2 systems are evaluated with ALD coatings on commercial inorganic sunscreen ingredients. ZnO was deposited on nanosized TiO2 particles (25nm primary) and TiO2 was deposited on nanosized ZnO (60nm primary) particles for enhanced UV protection. In the second aspect of this work, nanolaminated films of TiO2 and ZnO were prepared on the surface of submicron sized spherical silica (SiO2) particles. The large SiO2 substrate provides a particle size for the "UVA/UVB sun blockers" that is large enough to be used in ?soft focus? cosmetic products. In all instances, the composite particles are capped with an alumina (Al2O3) nanolayer to facilitate dispersion; rheological properties are addressed using an FDA approved sunscreen formulation. This Al2O3 nanolayer also prevents direct contact of the active TiO2/ZnO with the skin, thus protecting the skin from potential UV-photactivated reactions. The particle dispersions have been tested for UVA/UVB transmittance and Sun Protection Factors (SPF) have been calculated. ALD functionality is used to enhance primary particles that are currently used in commercial cosmetic and sunscreen products.

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