Polyphosphazene Elastomers, Gels, and Other Soft Materials.

Nearly all soft materials are based on organic polymer molecules. In other words they are derived from macromolecules constructed around the chemistry of carbon. Yet there are roughly 100 other elements in the periodic table that could in principle provide the building blocks for polymers and for soft materials. A few "inorganic" elements are incorporated into gels and related materials. Examples include silicate, aluminate, and titanate sol-gel substances, but the opportunities for diversification within these systems are relatively limited. The poly(organosiloxanes) (silicones) were the first hybrid inorganic-organic polymers to be discovered and they continue to play a major role in research and technology. Nevertheless, a need exists for additional systems that have the structural diversity found in the field of organic polymers, combined with the attributes of inorganic skeletal elements rather than carbon. It is with this objective in mind that we have devoted several decades to exploring the synthesis and diversification of the polyphosphazenes.