Substrate-Independent Approach to Dense Cleavable Polymer Brushes by Nitroxide-Mediated Polymerization

High grafting density polymer brushes are grown on an inimer coating bearing nitroxide-mediated polymerization (NMP) inimers and glycidyl methacrylate (GMA). The inimer coating is cross-linked on the substrate to provide an initiator layer with needed stability during long exposure to organic solvents at moderate to high temperatures. Surface-initiated nitroxide-mediated polymerization (SI-NMP) is conducted to grow polystyrene (PS) brushes on the coating with a sacrificial layer designed to cleave the brushes. The cleaved brushes have larger molecular weights than the corresponding free polymers. The grafting density of the brushes is as high as 1.12 chains/nm² throughout the brush growth, which is among the densest PS brushes reported so far. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) depth profiling are used to reveal the surface morphology and kinetics of the growth.