Self-assembled monolayers of alkylsilanes have been studied in tribological applications as a means to eliminate adhesion and wear in silicon based microelectromechanical systems (MEMS) devices. Unfortunately, they are easily damaged during incidental and intentional contact of surfaces, and roughness on the nanoscale, which focuses contact pressures to asperity contacts, plays a major role in their failure. Complementing prior studies employing AFM and FTIR, molecular dynamics simulations were performed to determine how nanoscopic curvature at asperities affects the pathways of heat and pressure dissipation in these films on a molecular scale. Simulated silica nanoparticles functionalized with alkylsilanes were used to simulate functionalized asperities. Tribologically relevant properties were examined, including gauche defect density and exposed silica surface. Surface curvature had a moderate direct effect on these properties, but more substantially, films on surfaces with nanoscopic curvature were found to have lower packing densities, which had a much greater impact on film integrity.

Molecular dynamics simulations of alkylsilane monolayers on silica nanoasperities: Impact of surface curvature on monolayer structure and pathways for energy dissipation in tribological contacts

244th National Meeting (2012)

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