X-ray Diffraction Analysis of the Structure of Poly (dichlorophosphazene)

Improved X-ray diffraction photographs, containing 63 unique reflections, have been obtained for highly purified poly(dichlorophosphazene) with the use of inclined-beam X-ray techniques. The results have been analyzed by a combination of unit cell indexing, model building, conformational analysis, and helical and optical transform methods. The chain-repeat distance is 4.92 A. An exact structural solution was precluded by an unusual combination of factors that lead to disorder of the system. However, the data are consistent with a cis-trans planar chain conformation and with a chain-packing arrangement that allows appreciable “rotational” disorder between adjacent chains and additional disorder with respect to the directional “sense” of different chains. These factors help to explain the unusual physical properties of this polymer.