Characterization of anisotropic structure in poly(phenylene vinylene) films

The evolution of the anisotropic structure in poly(phenylene vinylene) (PPV) films was studied using three nondestructive characterization techniques: prism waveguide coupling, infrared dichroism, and X-ray diffraction. The anisotropic PPV films were thermally converted from precursor drawn films at fixed length. The three-dimensional refractive indices, infrared dichroic ratios, crystal alignment, and orientation function were determined from each film. The results show that converted cast PPV film has a highly planar structure with a tendency for the PPV chains to orient parallel to the film surface. The a axis of the crystal unit cell is normal to the film plane. One-way stretching converts the film from a planar structure to a uniaxial structure.