STRUCTURE OF CHEMICALLY END-GRAFTED POLYMER-CHAINS STUDIED BY SCANNING FORCE MICROSCOPY IN BAD-SOLVENT CONDITIONS

In this paper, we study the polymer conformation of chemically end-gra fted polymer chains in bad-solvent conditions using a scanning force m icroscope. The polymer layers were prepared by exposing a gold substra te in a dilute toluene solution of thiol-terminated polystyrene (PS-SH ). Although the adsorption process took place in good-solvent conditio ns, the imaging was performed in water (bad solvent for polystyrene ch ains). For short incubation times and low concentrations, we identifie d individual polymer chains. For longer incubation times (higher surfa ce coverage), we observed microphase separation of the polymer monolay er into globular clusters. Using different molecular weights of PS-SH, we showed that the sizes of these clusters satisfy the scaling laws t hat were predicted for pinned micelles.