Surface Chemistries of Self-assembled Dental Silanes Monolayers

Abstract

Objectives: Organosilanes are commonly used in dentistry. Using organosilanes to form self-assembled monolayers (SAM), with the correct selection of functional groups of the organosilanes with respect to the organic and inorganic components, allows the creation of nano-level adhesion which could be a method to impede with the poor adhesion by making a more close intimate contact. This study was going to deposite two dental silanes SAM using different conditions and characterize their surface properties. Methods: Acdified 3-methacryloxyproyltrimethoxysilane (MPS) and 3-acryloyloxypropyltrimethoxysilane (ACPS) in 1% w/w ethanol were dip-coated on n-type Si(100) wafer for 5h and 22h. Uncoated silicon wafer served as control group. The coated surfaces were then characterized by ellipsometry, contact angle and surface free energy (SFE, in deionized water, formamide, diiodomethane and 1-bromonaphthalene model), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Results: The dip-coating method could coat dental silanes SAM on silica in 0.85-1.22 nm that agree with the molecular lengths. No significant correlation between silanization time and thickness of the dental silane films. The surface became hydrophobic after SAM coating in all groups, but overall the slight decrease of SFE did not significantly different from control group surface. Only MPS with 22hr dip-coating gave a significantly higher roughness (0.597 μm) as revealed by AFM, and XPS C1s peak (288.5eV) was observed which corresponds to O-C*=O. Conclusions: Dental silanes SAM can be easily formed using dip-coating method. However, the quality of the SAM is depending on the time and the silane itself.