MOLECULAR MOTIONS OF POLY(ETHYL ACRYLATE) AND POLY(N-BUTYL ACRYLATE) STUDIES BY SOLID-STATE NMR AND MOLECULAR-DYNAMICS COMPUTER EXPERIMENTS

The C-13 spin-lattice relaxation time (T1C) has been measured for bulk poly(ethyl acrylate) (PEA) and poly(n-butyl acrylate) (PBA) as a function of temperature. Some side-chain carbons in PEA and PBA show minima in T1c. On the basis of these results, the motion of CH3 carbons and the CH2 carbons in the side chain can be accounted for by the superposition of mainly two motions. One involves internal rotation or torsional oscillation of each functional group. The other is a slower motion induced by backbone motion. In addition, a molecular dynamics (MD) trajectory of 1.0-ns duration has been computed for a methyl-terminated atactic poly(ethyl acrylate) at 80-degrees-C. The results of the MD calculation were in general agreement with the results of C-13 spin-lattice relaxation.