Synthesis, Structures, and Emerging Uses for Poly(organophosphazenes)

Several different methods exist for the synthesis of poly(organophosphazenes), including ring-opening polymerization followed by macromolecular substitution, and several condensation methods. The macromolecular substitution alternative allows the linkage of a very wide range of different side groups to the inorganic backbone via reactions that permit the structure of the final polymer to be controlled by the electronic and steric characteristics of the side groups. The product polymers are elastomers, film-and fiber-formers, gels, membranes, and bioactive or biostable macromolecules that have many actual and potential biomedical or engineering uses. These opportunities are illustrated by a table of structure-property relationships which provides guidance for the design of polymers with predictable combinations of characteristics and potential uses.