FORMATION OF LAYER STRUCTURES IN H2SO4 INTERCALATED POLY(P-PHENYLENE VINYLENE)

X-ray-diffraction studies of highly oriented poly(p-phenylene vinylene ) (PPV) films before and after vapor phase or liquid-phase intercalati on by H2SO4 have been performed. In both cases the data support a stru ctural evolution dominated by a direct transformation of the original PPV polymer to a single, heavily doped phase. The best-fit model obtai ned from structure-factor refinements to the H2SO4-PPV equatorial data is fully consistent with the previously proposed ''stage-1'' layered structure in which the PPV chains and the sulfate ions form an alterna ting sequence of cation- and anion-radical layers with a monoclinic un it cell dominated by the PPV placement and lattice parameters of a=9.9 8 Angstrom, b=6.80 Angstrom, c=6.6 Angstrom, and gamma=94.5 degrees. N onequatorial scattering data suggest that at room temperature the H2SO 4 layer is not well ordered. Additional data sets probing the anisotro py within the equatorial plane (perpendicular to the PPV chain axis) c learly indicate that the insertion of H2SO4 layers occurs by creating galleries that are parallel to a-e plane of the PPV host polymer. This direction is effectively perpendicular to the commonly accepted inter calation scheme, which has these layers parallel to the pristine PPV [ 100] planes.