Mechanisms of orientational ordering of bipolar nematic droplets in a stretched polymer matrix

Oleg A. Aphonin

doi:10.1117/12.230656

19 January 1996 Mechanisms of orientational ordering of bipolar nematic droplets in a stretched polymer matrix

Oleg A. Aphonin

Proceedings Volume 2731, International Liquid Crystal Workshop on Surface Phenomena; (1996) https://doi.org/10.1117/12.230656
Event: International Liquid Crystal Workshop: Surface Phenomena, 1995, St. Petersburg, Russian Federation

Abstract

The orientational ordering of nematic (5CB) droplets with the bipolar director-field configuration, embedded in the uniaxially stretched polyvinyl alcohol matrix, is studied by polarizing optical microscopy. It is found that at small matrix deformations each bipolar structure is captured by the surface of the droplet cavity but, if the droplet non-sphericity further increases, there comes a point where the droplet abruptly reorients parallel to the long cavity axis. The measurements of the orientational distribution function testify the threshold nature of the bipolar droplet's ordering process. The heating of the slightly elongated polymer matrix above its glass transition temperature is found to eliminate the captured structures and produces the irreversible uniaxial orientation of the sample. The obtained information is analyzed in terms of three models taking into account the microrelief of the droplet surface, the ordered organization of polymer molecules at the droplet boundary, and the initial non- sphericity of droplet cavities, respectively. It is inferred that the formation of the supramolecular polymer structure at the matrix/droplet interface during the matrix curing process and its changes with stretching and heating are the governing factors responsible for the experimentally observed phenomena.

Citation Download Citation

Oleg A. Aphonin "Mechanisms of orientational ordering of bipolar nematic droplets in a stretched polymer matrix", Proc. SPIE 2731, International Liquid Crystal Workshop on Surface Phenomena, (19 January 1996); https://doi.org/10.1117/12.230656

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