COMPOSITE SPECTRAL DENSITY-FUNCTIONS FOR THE INTERPRETATION OF THE C-13 NMR RELAXATION BEHAVIOR OF POLYMERS CONTAINING HYDROCARBON SIDE-CHAINS - FREE AND RESTRICTED SIDE-CHAIN MOTION

C-13 NMR NT1 and NOE have been calculated by using composite spectral density functions describing polymer chain segmental motion and intern al rotation of a hydrocarbon side chain attached to the polymer backbo ne. Numerical results at two magnetic fields are presented as a functi on of the various motional parameters characterizing the various model s. NT1 and NOE relaxation parameters are well behaved and appear to ha ve practical value for describing the dynamics of these systems. The m odels have been applied to the relaxation data of poly(n-butyl methacr ylate) and poly(n-hexyl methacrylate) in toluene solutions. The dynami cs 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. (C) 1995 John Wiley & Sons, Inc.