Electrophoretic deposition of functionalized polystyrene particles for TiO2 multi-scale structured surfaces

Titanium is an interesting material for biomedical implants thanks to its physical and chemical properties. In particular, TiO2 coatings with a surface characterized by micro-patterning combined with nano-topography are extremely attractive for orthopaedic implants in terms of enhanced osteointegration and consequently improved implant fixation. In the present work, a new method for the preparation of TiO2 multi-scale structured coatings is presented. This method is based on three steps. Firstly, monodispersed polystyrene (PS) microsized beads are functionalized with TiO2 submicron particles by a wet process involving a cationic polyelectrolyte. Secondly, the resulting TiO2-PS composite particles in suspension are used to prepare coatings by electrophoretic deposition (EPD), a simple and flexible electrochemical technique. The EPD is performed cathodically, avoiding uncontrolled oxidation of the substrate. Finally, after removal of the PS spacers during the sintering process, TiO2 coatings with a combined micro- and nano-topography are achieved from deposits thicker than 100 µm. This achievement presents two relevant aspects: potential applications of the multi-scale structured TiO2 surfaces (particularly in the biomedical field); the simplicity and flexibility of the process used.