A Three Dimensionally Oriented Texture for Poly(tetrafluoro-p-xylene)

Films of poly(α,α,α‘,α‘-tetrafluoro-p-xylylene) prepared by vapor deposition polymerization are highly crystalline and have uniplanar orientation. This orientation is maintained on drawing ×10 at 350 °C, when the chains become aligned parallel to the direction of draw, leading to a texture of three-dimensionally oriented crystals. Thirty-five X-ray reflections are resolved by controlled rotation and tilting of the drawn specimen, and these can be indexed by a triclinic unit cell with dimensions a = 5.36 A, b = 5.92 A, c = 6.57 A (chain axis repeat), α = 97.0°, β = 63.1°, and γ = 73.1°, containing one monomer unit. Molecular mechanics favors a trans-planar conformation for the −CF2−CF2 linkage which is inclined at 90° to the adjacent phenyl groups, leading to a fiber repeat that is equal to that observed. Packing analyses point to a structure in which the phenyl groups are approximately perpendicular to the ac plane, and this gives good agreement between the observed and calculated structure amplitudes (R ...