Silanes for adhesion promotion and surface modification

Silanes are synthetic compounds containing one or more Si-C bonds. They have wide application in industry, dentistry and medicine. They are used mainly as surface coating agents for surface modification and as coupling agents for adhesion promotion between two dissimilar materials. The role of silanes as either surface coating or coupling agents depends on their chemical structure. A wide variety of reactive organic functional groups can be bonded to the silicon atom such that silanes can react with the functional groups of many substrates. When silanes are used as a surface coating agent, the physical and chemical properties of the substrate surfaces are improved. As coupling agents, silanes enhance the chemical bonding between two dissimilar materials. Reaction mechanisms to illustrate these actions of silanes will be presented. Some techniques of surface treatment such as air-abrasion and chemical etching to enhance the adhesion between a silane and the substrate surfaces will also be covered. Findings from current studies of various silanes as surface-coating and coupling agents in different areas, with an emphasis on dentistry, will be discussed. The focus will be on the findings of performance of silanes as surface coating and coupling agents in different aspects of applications, including limitations in use. Finally, an outlook about on future developing trends of silanes in dental materials science will be provided.