Journal of Materials Science

, Volume 49, Issue 8, pp 3080–3098 | Cite as

Chain flexibility versus molecular entanglement response to rubbing deformation in designing poly(oxadiazole-naphthylimide)s as liquid crystal orientation layers

  • Andreea Irina Barzic
  • Radu Dan Rusu
  • Iuliana Stoica
  • Mariana Dana Damaceanu


Four poly(oxadiazole-imide)s containing naphthalene rings, with different flexibility and molecular weight, are investigated with respect to their rheological properties to establish the optimal processing conditions from solution phase to film state for liquid crystal orientation purposes. The film uniformity and strength are determined by monitoring the flow behavior and chain entanglements. The solution rheological data are in agreement with film tensile testing, revealing that higher molecular weight favors chain entanglements and implicitly the film mechanical resistance. In order to analyze the suitability of these films as alignment layers their surface is patterned by rubbing with two types of velvet. Liquid crystal alignment of 4′-pentyl-4-biphenylcarbonitrile nematic is tested by polarized light microscopy. The resulting behavior is correlated with the polyimide malleability and characteristics of the textile fibers, namely their polarity, size, and mechanical features. The competitive effects between chain flexibility and entanglements, together with the interactions occurring between the polymer and velvet are analyzed in order to explain the surface regularity, which influences the uniformity of the liquid crystal alignment. The contrast between dark and bright states recorded on the liquid crystal cell indicates that some of these polynaphthalimides are promising candidates for liquid crystal display devices.


Liquid Crystal Polyimide Nematic Liquid Crystal Polarize Light Microscopy Polyimide Film 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This work was financially supported by PNII-RU project, code TE_221/2010, no. 31/10.08.2010.


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Andreea Irina Barzic
    • 1
    • 2
  • Radu Dan Rusu
    • 1
  • Iuliana Stoica
    • 1
  • Mariana Dana Damaceanu
    • 1
  1. 1.“Petru Poni” Institute of Macromolecular ChemistryIasiRomania
  2. 2.Faculty of Physics“Alexandru Ioan Cuza” UniversityIasiRomania

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