Synthesis and characterization of poly(organophosphazenes) bearing Schiff's base linkages

Two new classes of Schiff's base poly(organophosphazene)s have been synthesized and characterized. The substitution degree of the Schif's base linkage was found for the products of the form, [NP(O-Ph-CHO)(x)(O-Ph-CH=N-PhR)(y)](n)(polymer II series), where R are H, OCH3, OH(p), OH(m) and -N=N-Ph, was less than 35%, while the products of the second class, [NP(OCH2CH2OCH2CH2O-Ph-CHO)(x)(OCH2CH2OCH2-CH2O-Ph-CH=N-Ph-R)(y)](n) (polymer III series), where R are H, COOH(m), COOH(p), NO2, and OCH3, marked 65% on the average. The solubility of the polymers in the common organic solvents was found very poor, except such strong polar or aprotic solvents at elevated temperature. The existence of flexible spacer group connected to the Schiffs base linkage has greatly influenced the thermal properties of the polymers. DSC measurements revealed about 100 degrees C of melting transition for the polymer II series, while 214 degrees C for the polymer III series with exhibiting multistage of thermal transition. The DSC results gave some evidences that the products of polymer III series have potentials for the thermotropic liquid crystalline polymers.