SEGMENTAL MOTION OF SURFACE-BOUND SWOLLEN POLY(METHYL ACRYLATE)-D

Poly(methyl acrylate)-d (PMA-d), labeled in the backbone a position, w as prepared and adsorbed from toluene on silica at a coverage of 0.38 mg of PMA-d/mg of silica. This coverage was roughly that of the maximu m found in the adsorption isotherm. Comparisons of deuterium NMR spin- lattice relaxation time, T-1, and spin-spin relaxation time, T-2, for the adsorbed, swollen polymer at different temperatures were made to o btain information about the backbone motion of the surface-bound polym er. The results were consistent with a system where the fast local mot ions were similar to those in solution but the longer range segmental motions were more restricted than those in solution. The log-normal di stribution yielded mean correlation times which were 4-10 times slower for the surface-bound species than that in solution. The Hall-Helfand (HH) model with two correlation times yielded slow correlation times more than an order of magnitude slower for the surface species. Compar ed to previous studies on terminally attached polymers which formed ex tended blushes, liquid-like segments of randomly attached homopolymers have significantly reduced longer range segmental motions.