Spherulitic Morphology and Polymorphism of Poly[bis(3,4-dimethylphenoxy)phosphazene]

Abstract

Spherulitic morphology and phase transition of poly[bis(3,4-dimethylphenoxy)phosphazene] have been studied by optical microscopy, depolarized light-intensity measurements, DSC and X-ray diffraction. When the thin film of the polymer in its mesomorphic state was cooled down at 5°C/min to room temperature, several larger spherulites (B-type) appeared in the first stage, followed by development of a number of smaller spherulites (A-type). When the sample was heated subsequently, the A-type spherulites and B-type spherulites disappeared at 96°C and 110°C, respectively. These transition temperatures coincided with two DSC endothermic peaks. The extinction in the powder X-ray diffraction patterns of the spherulitic films indicated that thermodynamically less-stable α-type form (orthorhombic, primitive lattice) melted out in the vicinity of 100°C, but the β-type form (orthorhombic, base-centered lattice) remained. The A-type spherulites and B-type spherulites were composed of α-type crystals and β-type crystals, respectively. © 1995, The Society of Polymer Science, Japan. All rights reserved.