Carbon-13 NMR in Organic Solids: The Potential for Polymer Characterization

NMR in Chemistry--An Evergreen

“…However, only the isotropic parts of the interactions remain to be seen in the high resolution spectrum of a liquid whereas in a solid, the isotropic as well as the anistropic contributions to the line shape are obscured by the usually much larger dipolar broadening. Fortunately, during the past decade these limitations have been circumvented to a significant degree by the development of a new field of NMR-the high resolution NMR spectroscopy of solids (25,(40)(41)(42)(43)(44). These developments have already changed the character of NMR studies of solids and polymers, and there is a steady stream of new applications.…”

“…This can extend unduly the data acquisition time necessary to obtain an adequate SIN. For tunately, the problem can be alleviated with an ingenious scheme of cross polarization introduced by Hartmann & Hahn in 1962 and first applied to \3C nuclei by Pines, Gibby & Waugh (40,44) in 1973.…”

“…Hartmann & Hahn proposed that by doing the cross-polarization in a double rotating-frame, spin-locking experiment, the energies could be matched. The RF rotating field There are two different ways of accomplishing the cross polarization -spin locking and adiabatic demagnetization in the rotating frame (40,44). In addition, Pines and co-workers (25,41) (46), studies of solid biopolymers, and applications in polymer chem istry (43,44,47).…”

“…The RF rotating field There are two different ways of accomplishing the cross polarization -spin locking and adiabatic demagnetization in the rotating frame (40,44). In addition, Pines and co-workers (25,41) (46), studies of solid biopolymers, and applications in polymer chem istry (43,44,47). Their success is attributable in large measure to the rapid progress in solid state digital and RF components that has made feasible the high power RF pulse sequences, better recovery and sensi tivity of the receiver detection system, and the use of Fourier transform methods.…”

“…It seems worthwhile, however, to at least mention several of the other main directions. For example, the long tradition of using NMR to study polymers (6 1 -63) is being expanded these days by taking advantage of the new discoveries and progress in high resolution NMR spectroscopy of solids (43,44,47). The same techniques are being applied to the important field of surfaces and catalysts (64).…”