Applications and limitations of deuterium labeling methods to neutron scattering studies of polymers

Deuterium labeling techniques have been widely used to study polymer chain configuration and motion, based on the assumption that the H‐ and D‐ chains are thermodynamically identical and that the interaction parameter between them, X HD is zero. By an appropriate choice of the degree of polymerization and temperature, both critical scattering and phase separation can be made to occur, due solely to the small but finite thermodynamic differences between protonated and deuterated molecules. These experiments helped delineate the range of validity of the assumptions which had been used hitherto in neutron scattering studies of polymers. The majority of previous experiments, carried out at modest molecular weights, have been shown to be in large part unaffected by such effects.