Analysis of Extraordinary Birefringence Dispersion of Uniaxially Oriented Poly(2,6-dimethyl 1,4-phenylene oxide)/Atactic Polystyrene Blend Films

Abstract

The birefringence dispersion of uniaxially oriented poly(2,6-dimethyl 1,4-phenylene oxide) (PPO)/atactic polystyrene blend films has been investigated by polarization-modulated transmission spectro-ellipsometry measurements. The films show reverse birefringence dispersion in the region of PPO volume fraction from 0.21 to 0.29, where the birefringence is negative and close to zero, indicating ordinary refractive index dispersion. The reverse birefringence dispersion can be explained by the birefringence equation of a multicomponent system based on the preconditions that the intrinsic birefringence of each component in the blend is not changed and the form birefringence is ignored. Furthermore, it has been found that the orientation functions change depending on the volume fractions by the new method for obtaining orientation functions from birefringence dispersion.