SULFUR-NITROGEN-PHOSPHORUS POLYMERS

Macromolecules with backbones of sulfur, nitrogen and phosphorus atoms have only been successfully prepared in the last three years and the study of these materials represents a new and interesting area of research. In this article the synthesis and properties of the three currently known classes of sulfur-nitrogen-phosphorus polymers are reviewed. These include poly(thiophosphazenes) and poly(thiazylphosphazenes), which, in addition to nitrogen and phosphorus, possess skeletal three-coordinate sulfur(IV) and two-coordinate sulfur(III) atoms, respectively. Poly(thionylphosphazenes), which were discovered in 1991, appear to represent the most stable and diverse class of S-N-P polymers prepared to date and possess skeletal four-coordinate sulfur(VI), nitrogen and phosphorus atoms. Developments to date concerning this particular polymer system are also described