Polyphosphazenes with High Refractive Indices: Optical Dispersion and Molar Refractivity

The optical properties of a series of high refractive index polyphosphazenes were investigated. The wavelength-dependent change in refractive index (optical dispersion) associated with two selected polymers was examined using variable-angle spectroscopic ellipsometry. Values of the Abbé number for these polymers were calculated. These systems have a ν D = 20−25, which compares closely with other organic polymers with similar refractive indices. Calculation of the molar refractivity ( R m ) associated with the [N P] repeat unit structure yielded a value of R m [N P] = 14.36 cm 3 /mol. This value is compared with other polymer repeat unit structures. The comparison indicates that the [N P] repeat unit has a linear polarizability close to that found in conjugated [C C] bonds.