Grafting of poly(sodium styrenesulfonate) onto gold surface from NaNO3 solution

The chemical grafting of thiol terminated poly(sodium styrenesulfonate) (HS-PSSS) chains from sodium nitrate (NaNO3) salt solution to a gold surface was investigated with a quartz crystal microbalance with dissipation monitoring (QCM-D) in different salt concentrations. It was found that at low salt concentration grafting density of HS-PSSS was low and the grafted chains adopted a mushroom conformation. With the increase of salt concentration polyelectrolyte chains underwent a transition toward coiled state due to reduction of electrostatic repulsion and as a result more chains were grafted on the surface. When the grafting density reached a certain limit after which further grafting caused repulsion between already grafted HS-PSSS chains and as a result grafted chains adopted a brush conformation.