An experimental study of the conformational energies of poly(neopentyl glycol succinate)

Abstract

Values of the dipole moment ratio 〈µ²〉/nm² of poly(neopentyl glycol succinate), obtained from dielectric measurements on dilute solutions of the polymer in benzene, varied from 0.548–0.586 in the temperature range 30–60 °C. From thermoelastic experiments, performed on polymer networks prepared by cross-linking hydroxy-terminated poly(neopentyl glycol succinate) chains, a value of 0.52 × 10^–3 K^–1 was obtained for the temperature coefficient of the unperturbed dimensions. Critical analysis of the thermoelastic and dielectric results, using the rotational isomeric state model, suggests that whereas the gauche states about the C–C bonds of the neopentyl glycol residue have an energy of ca. 0.6 kcal mol^–1 lower than that of the alternative trans states, the former conformational states are disfavoured with respect to the corresponding trans states in the case of the central C–C bond of the succinyl residue. This study also suggests that the skeletal bonds of the type OC–C bonds are almost freely rotating.