Probing Molecular Mobility at the PNIPAM Brush Surface*

Diffusion of single polyelectrolyte molecules, poly 2- vinylpyrindine (P2VP), on N-isopropylacrylamide (PNIPAM) brush was studied by single molecule fluorescence techniques. The dependence of the surface diffusivity on varying temperature and brush thickness was studied. We observed a strong dependence of the surface diffusivity on the brush thickness while a minor dependence on the temperature. We attribute these effects to the surface mobility of the adsorption sites of the P2VP to the PNIPAM brush surface.