Deposition of Bioactive Titania Layers on Non-Metallic Substrates under Ambient Conditions due to Hydrolysis of Titanium Oxysulfate Solution

Abstract

The paper presents a simple chemical treatment to provide various non-metallic substrates such as polypropylene or polyethylene with in vitro bioactivity or ability to deposit apatite in SBF. Anatase/rutile dual layers were deposited at low temperature on the substrates when they were soaked in TiOSO4/H2O2 solution and aged in hot water: The dense bottom layer predominantly consisted of rutile, while the upper layer consisted of loosely packed aggregation of anatase particles. The titania deposition was the results of compromise among two conflicting processes: 1) hydrolysis of TiOSO4 to yield either soluble titania-H2O2 complexes or titania, and 2) dissolution of the titania layer under the presence of H2O2. The dissolution-deposition equilibrium was found associated with pH of the sulfate solution. Thus, proper pH value in the treating solution was the key factor to control the formation of dense titania layers. The resulted titania layers were easily covered with fine apatite particles when soaked in SBF supersaturated with its component ions.