Fabricating Photocatalytic Titania Thin Films on Nylon

Photocatalytic titania thin-films were fabricated by a hybrid sol-gel method, and then deposited on nylon-6 substrates by dip-coating, followed by annealing at different temperatures (120 degrees C, 160 degrees C, and 200 degrees C) for 16 h. The effective solids loading of the sol was varied as 150: 1, 125: 1, 100: 1, 70: 1, and 50: 1 moles of titania to water. The mineralogy, microstructure, adhesive bonding, and photocatalytic properties of the films were determined using laser Raman spectroscopy, optical and scanning electron microscopy, pull-off tests, and methylene blue photodegradation tests, respectively. Crystalline anatase nano-particles were formed by the hybrid sol-gel method and further recrystallisation occurred during subsequent heat treatment. Coherent titania thin-films were fabricated on all samples, except at the highest solids loading (50:1) where an inhomogeneous rough film was observed. Oxidative degradation of nylon occurred at regions not covered by the protective TiO2 film. All coatings were strongly adhered to the substrate irrespective of the solids loading or annealing temperature. Furthermore, all the films were photocatalytic, with the best performance seen at the highest heat treatment temperature. The effect of solids loading on the photocatalytic performance was not clear. The work showed that a coherent photocatalytic thin film of TiO2 can be successfully deposited on nylon-6 substrates.