UNUSUAL PHASE-BEHAVIOR OF SOME POLY(DIALKOXYPHOSPHAZENES)

An unusual transition from the mesomorphic state to the amorphous state has been found on cooling some poly(dialkoxyphosphazenes). This transition is proved by data obtained from thermomechanical analysis and optical and X-ray investigations. A generalized phase diagram is constructed for these polymers showing the influence of the alkoxy side group length on their glass transition temperatures, crystallization, and ability to form mesophases. The competition of interactions of the polar inorganic main chains and the side methylene chains has been proposed to be an important factor which controls the phase behavior of poly(dialkoxyphosphazenes).