POLYMER AND MATERIALS SYNTHESIS AND PROPERTIES .2. HYBRID PHOSPHAZENE-ORGANOSILICON POLYMERS .1. BACKGROUND, RATIONALE, AND SMALL-MOLECULE MODEL-COMPOUND CHEMISTRY

Most of the polymers that have been synthesized and studied over the p ast 50 years are organic macromolecules. However, many advantages exis t for the development of polymers with inorganic backbones. The first major class of inorganic backbone polymers to be developed widely were the poly(organosiloxanes) (silicones), and these now are the subject of broad industrial and fundamental interest. Polyphosphazenes are a r elatively new class of inorganic backbone polymers which rival many or ganic systems in their molecular structural diversity and property var iations. They constitute only the second group of inorganic-organic po lymers to be developed extensively. An emerging field of research invo lves an attempt to create a new area of polymer science at the interfa ce between these two subjects, by the synthesis of hybrid organo-phosp hazene-organosilicon systems. This review is a summary of recent progr ess in this new field.