Bioactive glass-mesoporous silica coatings on Ti6Al4V through enameling and triblock-copolymer-templated sol-gel processing.

Abstract

The combination of thick glass coatings that can protect Ti6Al4V from corrosion in the body fluids, and mesoporous silica films able to readily induce the formation of apatite when immersed in a simulated body fluid (SBF), has been investigated in this work as a possible route towards more resistant and long-lasting implants. Glasses in the system Si-Ca-Mg-Na-K-P-O with thermal expansion coefficients close to that of Ti6Al4V were prepared and used to coat this alloy by an enameling technique. However, the glasses apt to coat Ti6Al4V exhibited a very limited capacity to induce apatite formation in SBF. In order to enhance their bioactivity, a thin film of mesoporous silica was applied on the exterior of the specimens by spin coating a sol-gel solution. When tested in SBF, these coatings induced apatite formation after 7 days. The mesoporosity of the silica film was created through a triblock-copolymer-templating process. The diameters of the mesochannels could be adjusted by changing the size of the directing agent. A preferred alignment of the mesostructure was observed. The removal of the organic templates could be achieved through a photocalcination treatment, which, compared to conventional thermocalcination, offered several advantages.