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Proceedings Paper

Kinetics study of phase separation in polyacrylic acid/nematic LC system by optical technique
Author(s): Maria Mucha; Z. Krolikowski
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Paper Abstract

Thin polymer layers containing liquid crystal LC of non- linear optical properties were obtained from polyacrylic acid. Samples were produced by phase separation as a consequence of chemical polymerization (PIPS method) resulting in precipitation of liquid crystals in the form of droplets in a polymer matrix being formed. Films were produced in variable conditions of polymerization time and temperature and different content of an initiator (1 - 3 wt%). They contained of 10 - 40 wt% of LC. The cell thickness was constant and equal to 20 micrometers . Systems obtained in this way were subjected to thermo-optical and electro-optical studies, morphological structure investigation and DSC analysis. The polymerization time has a significant influence on the size and number of LC droplets. The presence of benzoyl peroxide can cause partial destruction of LC properties which is reflected by a decrease of isotropization temperature TI of the liquid crystal. An increase of the initiator amount shortens the time of polymerization (ti), while process enthalpy ((Delta) H) increases. Hence, the liquid crystal separation time decreases as well. Films prepared by this method present good electro-optical properties. Rise and decay times of orientation are short and equal to 2 - 17 ms (depending on driving voltage applied) and about 80 ms, respectively. Threshold voltage for the best sample is equal to 5 V. Optimal conditions are found: LC content equals 20%, wt(i) equals 1%, polymerization temperature Tp equals 100 - 110 degree(s)C.

Paper Details

Date Published: 27 June 2002
PDF: 10 pages
Proc. SPIE 4759, XIV Conference on Liquid Crystals: Chemistry, Physics, and Applications, (27 June 2002); doi: 10.1117/12.472197
Show Author Affiliations
Maria Mucha, Technical Univ. of Lodz (Poland)
Z. Krolikowski, Technical Univ. of Lodz (Poland)


Published in SPIE Proceedings Vol. 4759:
XIV Conference on Liquid Crystals: Chemistry, Physics, and Applications

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