A STUDY OF SOLUTION POLYMERIZATION OF POLYPHOSPHAZENES

Several alkoxy/aryloxy-substituted phosphazene polymers [P(OR)2=N]n(R = CH3, C6H5, C6H4CH3, CH2CF3, C6H4C6H5, C6H4C1, C6H4Br, C8H10) were prepared by the reaction of poly(dichlorophosphazene) with their corresponding sodium salts. The poly(dichlorophosphazene) was obtained by the solution polymerization of hexachlorocyclotriphosphazene in 1,2,4-trichlorobenzene. Sulfamic acid and ammonium sulfamate were used as catalysts. Apparently sulfamic acid functions as a catalyst through its acid group in some decomposed form. Toluenesulfonic acid and sulfobenzoic acid were new catalysts developed for solution polymerization. The polymerization favors a cationic mechanism. Promoters were found to speed up to polymerization reaction. Effects of different parameters including dilution, catalyst concentration, and promoter concentration on the properties of the final polymer were investigated. The changes in molecular weight and molecular weight distribution of the polymer as a function of polymerization reaction time were noted. The nucleophilic reaction was studied, and the effect of reaction time and temperature on the properties of the final polymer was investigated. Ring opening on fully substituted cyclotriphosphazenes at elevated pressures and temperatures was unsuccessful. The polymers were characterized by differential scanning calorimetry, gel permeation chromatography, infrared spectroscopy, and 31P solution nuclear magnetic resonance spectroscopy. © 1990, American Chemical Society. All rights reserved.