“…The structure of the isotropic melt of the polyphosphazene retains the main features of the mesophase structure but is distinguished by a coil conformation of macromolecules. 212 In the 453 ± 493 K temperature range, rheological properties and structural characteristics of the mesophase melt of the polymer substantially change, which is accompanied by a thermal effect. 213 It is believed that this change corresponds to a conformational transition of macromolecules into a structure intermediate between one-dimensional layered and two-dimensional pseudo-hexagonal structures.…”