A Three-Dimensionally Oriented Texture for Poly(α,α,α′,αα′-tetrafluoro-p- xylylene)

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Abstract

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 threedimensionally 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 Å, b = 5.92 Å, c = 6.57 Å (chain axis repeat), α = 97.0°, β= 63.1°, and y = 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 = 0.18). The crystal structure is similar to that proposed for the α-form of poly(p-xylylene), except that the chain separation along the a axis direction is increased due primarily to the presence of the fluorine atoms.

Original languageEnglish
Pages (from-to)7845-7852
Number of pages8
JournalMacromolecules
Volume32
Issue number23
DOIs
StatePublished - 16 Nov 1999

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