Kinetics of Dynamic Polymer Brush Formation

The kinetics of dynamic polymer brush formation, which is driven by interfacial segregation of amphiphilic block copolymers, was investigated by quartz crystal micro-balance (QCM) and neutron reflectivity (NR). High speed formation kinetics in the early stage was probed by QCM, and the later stage, where the formation kinetics became relatively slow, was investigated by NR. QCM detected fairly the fast brush formation kinetics on the order of tens of seconds for the copolymers in use. The dynamic polymer brush rapidly grows initially and hence repairs itself when the surface is damaged and the brush is partly lost. This fast dynamic polymer brush formation is driven by relatively slow diffusion of block copolymers in the matrix. The slow diffusion suggests that the diffusion mechanism is not controlled by simple Rouse or reputational diffusion but by the activation hopping mechanism of self-assembled diblock copolymers.