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-grafted polymer chains in bad-solvent conditions using a scanning force microscope. The polymer layers were prepared by exposing a gold substrate in a dilute toluene solution of thiol-terminated polystyrene (PS-SH). Although the adsorption process took place in good-solvent conditions, the imaging was performed in water (bad solvent for polystyrene chains). For short incubation times and low concentrations, we identified individual polymer chains. For longer incubation times (higher surface coverage), we observed microphase separation of the polymer monolayer into globular clusters. Using different molecular weights of PS-SH, we showed that the sizes of these clusters satisfy the scaling laws that were predicted for pinned micelles.