Solid-State Deuterium NMR of Acrylate Polymers

摘要

Solid-state deuterium NMR has proven to be a valuable technique for examining the molecular motions of polymers. Selective deuteration of acrylate monomers has provided a site for observing the motions of the polymer backbone. Polymers of methyl, ethyl, and butyl acrylate alpha-d1 and acrylonitrile alpha-d1 and acrylamide-alpha-d1, were prepared free radically under the same conditions. Crosslinked polymers were also formed using an acrylate and appropriate diacrylate as crosslinking agent. Of the two crosslinked systems examined, one contained deuterium in the main chain backbone while the other was deuterated in the crosslink. Solid state deuterium NMR solid echo spectra and relaxation data were obtained for these polymers at various temperatures. The spectra show that the backbone motion of the polyacrylates and crosslinked polyacrylates is similar, being very slow below Tg and random (isotropic) above Tg. The motion of the polyacrylonitrile backbone around Tg is very rigid but well above Tg the spectra indicate a specific jump motion is occurring. Reprints. (aw)