CHAIN SEGMENTAL MOTION AND SIDE-CHAIN INTERNAL ROTATIONS OF POLY(1-NAPHTHYLALKYL ACRYLATE)S IN SOLUTION STUDIED BY C-13 NUCLEAR MAGNETIC-RELAXATION

C-13 longitudinal relaxation times and nuclear Overhauser enhancements were measured as a function of temperature in three magnetic fields f or a series of poly(1-naphthylalkyl acrylate)s in 1,1,2,2-tetrachloroe thane-d2. Variable-temperature C-13 transverse relaxation time measure ments at 75.4 and 125.7 MHz also were undertaken. The relaxation data have been described by using various models for main-chain segmental m otion and side-chain internal rotations. Among these, the Dejean-Laupr etre-Monnerie (DLM) model offered the best description of segmental mo tion for the poly(1-naphthylalkyl acrylate) chains. Internal rotations about the side-chain bonds, including naphthyl internal motion, were described by hindered rotations superimposed on segmental motions, the latter being described by the DLM model. An attempt was made to corre late rates and activation energies associated with the various modes o f reorientation in the aforementioned polymers with the rates of excim er formation between the side-chain naphthalene chromophores.