Photocatalytic self-cleaning keratins: A feasibility study

Anatase nanocrystals were successfully synthesized and deposited on protein keratin-type wool fibers with good compatibility and significant photocatalytic self-cleaning activity using the sol-gel process. Due to the low chemical resistance and liability to photo-degradation of protein materials, the effect of the acid catalyst used in the sol synthesis was studied. The sols were prepared using oxidizing and non-oxidizing catalysts, nitric acid and hydrochloric acid, respectively, for the hydrolysis and condensation reactions of the titanium dioxide precursor. The size distribution and crystallinity of the sols were characterized by X-ray diffraction spectroscopy and photon correlation spectroscopy. The compatibility of sol formulations and wool is thoroughly compared and discussed by analyzing fibers photo-degradation, surface morphology and self-cleaning properties including stain degradation and colorant decomposition. The UV absorption and mechanical properties of wool fibers before and after coating are also discussed. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.