Nuclear magnetic relaxation without spin diffusion in polymers at interfaces.
We consider theoretically the possibility of solid state NMR experiments with frozen linear polymer chains at interfaces. Three different cases are studied, namely, when the macromolecules are grafted on the surface, when they are adsorbed, and when they are very strongly adsorbed from a melt that is subsequently washed by a good solvent. The latter case is somewhat intermediate between the two former ones. For each case, we consider the relaxation when paramagnetic centers are located on the surface. We show that the shape of the relaxation curves depends critically on the monomer concentration profile, and exhibits characteristic power-law variations.
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