Molecular dynamics simulations were applied to investigate the adsorption and diffusion processes of a single hydrophilic polyvinylalcohol) chain with different chain lengths on a hydrophobic graphite surface. It was expected that the chain and the surface "dislike" each other because one was hydrophilic and the other was hydrophobic. But surprisingly, a short polyvinylalcohol chain was well adsorbed on the surface, accompanied by large changes in the chain configuration. With increasing degree of polymerization (N), the chain turns gradually from two-dimensional adsorption to possessing certain height in the direction perpendicular to the surface. Moreover, the adsorption energy increased and the diffusion coefficient decreased with increasing N. In particular, for N = 20 in equilibrium, the hydroxyls of this short chain were close to the graphite surface in the stable adsorption configuration. In addition, the effective dielectric constant was changed to 76.0 to mimic good solvent condition.

Molecular Dynamics Simulation Study on Adsorption and Diffusion Processes of a Hydrophilic Chain on a Hydrophobic Surface. Wang, X.L., Lu, Z.Y., Li, Z.S., Sun, C.C.: Journal of Physical Chemistry B, 2005, 109[37], 17644-8