Poly(Phosphazophosphazenes): A New Class of Inorganic Polymers with Short-ChainBranching

摘要

A method is reported for the introduction of molecular asymmetry and materialsfree volume at the polymerization stage to yield a new series of polyphosphazenes. Here we report a method for the introduction of molecular asymmetry and materials free volume at the polymerization stage to yield a new series of polyphosphazenes. gem-Bis(trichlorophosphazo)tetrachlorocyclotriphosphazene (1) undergoes an unusual low-temperature, ring-opening polymerization to form a high molecular weight poly(phosphazophosphazene) (2) This is the first example of a phosphazene polymer with well-defined short-chain branching. Polymer 2 can act as a macromolecular intermediate in selected cases and can be converted to hydrolytically stable, branched-structure poly(organophosphazenes). Air-sensitive crystals of 1 were placed in an airless, flask, and the entire apparatus was evacuated through a vacuum line. Under a dynamic vacuum, the flask and its contents were heated at 150 C for 2 h with stirring. The molten 1 was slowly converted to an immobile gel.