Composite spectral density functions for the interpretation of the 13C NMR relaxation behavior of polymers containing hydrocarbon side chains. Free and restricted side chain motion

¹³C NMR NT₁ and NOE have been calculated by using composite spectral density functions describing polymer chain segmental motion and internal rotation of a hydrocarbon side chain attached to the polymer backbone. Numerical results at two magnetic fields are presented as a function of the various motional parameters characterizing the various models. NT₁ and NOE relaxation parameters are well behaved and appear to have practical value for describing the dynamics of these systems. The models have been applied to the relaxation data of poly(n-butyl methacrylate) and poly(n-hexyl methacrylate) in toluene solutions. The dynamics of the two polymers are characterized by a very localized backbone motion and restricted internal rotation about successive C? C bonds of the side chains. © 1995 John Wiley & Sons, Inc.