The effect of polymer concentration on the dynamics of adsorbed poly(N-isopropylacrylamide) at particle surfaces in water

Results are presented of a light scattering study of the dynamics of absorb ed poly(N-isopropylacrylamide) (PNIPAM) chains at the surfaces of poly(N-te rt-butylacrylamide) (PNTBA) latex particles using several different feed we ight ratios of PNIPAM to latex particles. The adsorbed layer dynamics under the present experimental conditions were postulated to include both the ex tended-to-loopily adsorbed state transition of tightly adsorbed chains and the diffusion of tenuously adsorbed chains. The dynamics were described by a nonexponential rate process. The relaxation times calculated were found t o increase with increasing polymer to latex feed weight ratio. Kinetic cons traints were inferred to play a crucial role in controlling the overall dyn amics. A higher polymer to latex feed weight ratio was considered to enhanc e these kinetic constraints. (C) 1999 Academic Press.