FT-IR and XPS surface characterization of allyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane mixture adsorbed onto titanium substrate

Organofunctional trialkoxysilane coupling agents are used in restorative dentistry in order to enhance the bonding between restorative and veneering composites and inorganic materials, such as E-glass fibres, grit-blasted dental ceramics, base and noble alloys, and also for composite filler treatment. The most commonly used silane for coupling composite resins to metals, ceramics and silica-coated composites (for repair) is 3-methacryloxypropyltrimethoxysilane (MPS). The aim of this study was to determine whether an allyltrimethoxysilane (ALS) and MPS mixture could form a stable, adhesion-promoting metallo-siloxane layer on a titanium substrate. Two mixtures (0.25 vol%+0.25 vol% and 0.50 vol%+0.50 vol%) were applied to the titanium substrate and cured at room temperature or in an oven (at 110°C for 1 h). The siloxane films were characterized using XPS, RAIR and AFM. The results showed that all samples had siloxane films on them. According to the XPS analysis it might be suggested that silanization with ALS seemed to form a more Si-rich siloxane film compared to silanization with MPS. It was concluded also that MPS + ALS silane mixtures would be worthy of further investigation. The FTIR analysis suggested that Si-O-Ti bonds were formed to bond the siloxane film to the Ti substrates.