Polyphosphazene

Polyphosphazenes include a wide range of hybrid inorganic-organic polymers with a number of different skeletal architectures that contain alternating phosphorus and nitrogen atoms. Nearly all of these molecules contain two organic or organometallic side groups attached to each phosphorus atom. These include linear polymers with the formula (N=PRR)_n, where R and R are organic or organometallic side groups. The linear polymers are the largest group, with the general structure shown schematically in the picture. Other known architectures are cyclolinear and cyclomatrix polymers in which small phosphazene rings are connected together by organic chain units. Other architectures are available, such as block copolymer, star, dendritic, or comb-type structures. More than 700 different polyphosphazenes are known, with different side groups (R) and different molecular architectures. Many of these polymers were first synthesized and studied in the research group of Harry R. Allcock at The Pennsylvania State University.