S. Park, J. Blackwell, S. Chvalun
Apr 1, 2000
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Influential Citations
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Journal
Polymer
Abstract
Abstract Films of poly(cyano- p -xylylene) (CN-PPX) synthesized by vapor deposition polymerization are highly crystalline and can be prepared with uni-planar orientation. This orientation is maintained after drawing the film 700% at 350°C, when the chains become aligned parallel to the direction of draw, leading to a mosaic texture of doubly-oriented crystals. Three-dimensional wide angle X-ray data show that the polymer has a monoclinic unit cell with dimensions a=5.96 A , b=13.52 A , c=6.48 A and β =135.9°, containing two monomer units from symmetry related chains. The unit cell is almost identical to that of the α-form of the unsubstituted polymer, poly( p -xylylene), except for the increased b dimension ( b=10.64 A in PPX), which is due to the –CN substituent. Molecular modeling and X-ray simulations show that the two polymers have similar crystal structures. The best agreement between the observed and calculated structure amplitudes ( R =0.21) is for a model where there is random substitution of the –CN groups.