Self-assembled monolayers of organophosphonic acids supported on teeth

Controlling the surface properties of the tooth, e.g. adsorption and adhesion to its surface is of interest for use in dental applications. This work investigates self-assembled monolayers (SAMs) of organophosphonic acids supported on the surface of human teeth. The SAMs were prepared via a solution-phase reaction of C18H37P(O)(OH)2 with enamel chips. ATR suggests the formation of SAMs with highly ordered alkyl groups (based on the CH2 stretching). Water contact angles of the enamel-supported SAMs are in the range ∼100–70° (advancing/receeding), which is consistent with the formation of hydrophobic surfaces. According to atomic force microscopy imaging, the SAM growing process appears as the formation of islands on the surface of the tooth. At the late stages of the reaction, islands merge yielding larger domains covering almost the entire surface of the tooth. The size of these domains undergoes a complex change during the course of the deposition and after 100 h of reaction it becomes ∼40–60 nm in lateral dimension. The surfaces prepared demonstrate good stability in the presence of water and organic solvents, showing the potential uses of SAMs of organophosphonic acid for permanent modification of the surface properties of the tooth.