Specialized phosphorus containing polymers

Surprisingly, very few publications reporting the use of bismuth catalysts have appeared in the field of polymer chemistry although bismuth(III) salts, due to their ability to form weak complexes with various heteroatoms and functional groups commonly encountered in polymer chemistry, clearly have potential as catalysts (Bronsted or Lewis cationic activation) for the synthesis of these special multi-Lewis base type of macromolecules. In one of the few reported examples, the polycondensation of dimethyl terephthalate with 1,4-butanediol has been carried out under BiCls catalysis and leads to telechelic poly(butylenes terephthalates) [125]. Bi(0Tf)3 xH20 has been patented as a catalyst for the cationic polymerization of THF using selected phosphorus-containing compounds [126]. 

Macromolecules that contain phosphorus as a skeletal atom have been studied in detail for many years. Yet, compared to the vast array of known carbon-backbone polymers, macromolecules based on phosphorus have occupied only a small and very specialized niche. We have been systematically exploring the prospect that a broad new class of high polymers, the poly-(organophosphazenes) (III), can be synthesized in which phosphorus rather than carbon plays a key role in the skeletal chain (1-3). 

---