Poly(organophosphazenes): Synthesis, unique properties, and applications

Poly(organophosphazenes) are the first inorganic backbone polymers to be developed on a broad scale since the discovery of the silicones in the 1940's. Polyphosphazenes are synthesized by ring‐opening polymerization of cyclic halogenophosphazenes, followed by nucleophilic replacement of the halogen atoms in the polymer by organic units. Factors that affect the ring‐opening polymerization are discussed, together with the properties and uses of the new polymers.