Direct Observation of In-plane Diffusion of Isolated Polymethacrylates Chains on Solid Surfaces

Polymer composites have attracted a great deal of attention as light-weight structural materials with excellent mechanical properties. It has been widely accepted that the polymer adsorbed layer on the filler surface is a key to controlling the performance of the material. Although there is no doubt that the interaction between polymer and solid surface is of importance to designing it, the effect of the interaction on the dynamics of chains on the surface is not yet fully understood. Therefore, we visualized the in-plane diffusion of poly(methyl methacrylate) (PMMA) and poly(tert-butyl methacrylate) (PtBMA) chains on solids using atomic force microscopy. We also tackled the effect of condensed surface water on the in-plane chain diffusion. The diffusion of PMMA chains was not observed regardless of the thickness of the water layer. On the other hand, PtBMA chains diffused on a wet surface, while they did not on a well-dried surface. These results imply that the presence of the bulky side group alters the interaction with the solid surface having the condensed water layer.