Thermoelastic and dielectric studies of poly(3,3-dimethyl oxetane) chains

Poly(3,3-dimethyl oxetane) was synthesized by ring opening polymerization of 3,3-dimethyl oxetane. Elongation experiments were performed on unswollen elastomeric networks prepared from this polymer over the temperature range 30–90°C. The changes in the tensile stress while the networks crystallized were examined at various elongations. From thermoelastic data which were free from the effects of network crystallization, the temperature coefficient of the chain dimensions was found to be 1.1 × 10^?3 K^?1 in the vicinity of 60°C. The dipole moment ratio and its temperature coefficient were also measured; the average values of these parameters at 30°C were 0.20₆ and 2.5 × 10^?3 K^?1, respectively. All of these experimental-configuration-dependent properties were critically interpreted in terms of the rotational isomeric-state model. In comparing theory and experiment, conclusions were obtained which confirm earlier results according to which gauche states about C—C skeletal bonds in poly(3,3-dimethyl oxetane) are strongly favored over the alternative trans states.