Carbonate-Terminated Self-Assembled Monolayers for Mimicking Polycarbonate Surfaces

Polycarbonates (PCs) are known for their durability, optical transparency, and biocompatibility. Despite the stability of PC, they tend to swell after being exposed to organic solvents, leading to a change in the hydrophobicity of the polymer layers and making it difficult to study the interfacial properties of the polymer layers in contact with organic solvents. Organic thin films in the form of self-assembled monolayers (SAMs) have been utilized in various applications such as catalyst modifiers for hydrogenation reactions, anti-corrosion protectants for metal surfaces, and anti-adhesive films for biosensors. In this project, four targeted adsorbate molecules 3-COC11SH, 3-COC12SH, 2-COC11SH, and 2-COC11SH with different positional isomers of the carbonate groups were synthesized and their SAMs were generated on evaporated gold substrates. These nanoscale organic films will mimic bulk polymer coatings for evaluating the interfacial characteristics without suffering from surface reconstruction or swelling found in bulk polymer coatings. The adsorbate molecules were characterized using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. The corresponding SAMs were characterized by ellipsometry, contact angle goniometry, polarization-modulation infrared reflection-adsorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS). The contact angle data showed that the wettabilities of both SAM series were similar to the PEC-coated surfaces for a wide range of contacting liquids.