Study of the kinetics of mushroom-to-brush transition of charged polymer chains

The grafting of thiol-terminated poly[(2-dimethylamino)ethyl methacrylate] (HS-PDMEM) chains to a gold surface from a solution was investigated with quartz crystal microbalance with dissipation (QCM-D) in real time. The frequency and energy dissipation responses revealed a three-regime-kinetics of the grafting. The chains are quickly grafted in regime I forming a random mushroom. In regime II, the grafted chains have a rearrangement and form an ordered mushroom structure. The grafting is accelerated in regime III. As the grafting density increases, the chains form brushes. From regime II to III, the mushroom-to-brush transition occurs. The results were further supported by atomic force microscopy (AFM) imagines.