Monte Carlo simulations of liquid spreading on a solid surface: Effect of end-group functionality

The spreading of liquid droplets composed of molecules with or without reac tive end groups over a solid surface has been studied using Monte Carlo sim ulations, For molecules without reactive end groups, a molecular layering i n the spreading profiles is predicted, depending on the ratio of the magnit ude of intermolecular interactions to thermal energy. As intermolecular int eractions become smaller than thermal energy, the layered structure vanishe s. For molecules with reactive end groups, interactions between end groups and between end groups and the surface complicate the situation. By assumin g an end-to-end interaction between molecules and the pinning of end groups to the surface, a complex layered structure is obtained. Our simulation pr edicts spreading profiles that accurately describe the broad spectrum of da ta obtained from scanning microellipsometry for perfluoropolyalkylethers wi th and without reactive end groups. [S1063-651X(99)09911-0].