The methods of correlation optics are for the first time applied to study structure of liquid crystal (LC) – polymer (P) composites at various concentrations of LC and P. Their phase correlation function (PCF) was obtained considering LC-P composite as a random phase screen. The amplitude of PCF contains information about number of LC domains and structure of LC director inside of them, while a half-width of this function is connected with a size of these domains. We studied unpowered and powered composite layers with a thickness of 5 μm. As liquid crystal and polymer were used nematic LC E7 from Merck and photopolymer composition NOA65 from Norland. Concentration of polymer φ_P was varied in a range 10-55 vol. %. In good agreement with previous studies by SEM technique we detected monotone decrease of LC domains with concentration of polymer. With application of electric field, amplitude of PCF behaves differently for the samples with different polymer content. For the samples with φ_P>35 vol. % (samples having morphology of polymer dispersed LC), this dependence is monotonic. In turn, if φ_P<35 vol. % (samples with polymer network LC morphology), the amplitude of PCF non-monotonically depends on the applied voltage going through a maximum. The latter fact is explained by transformation of orientational defects of LC phase with the applied voltage.

Date Published: 30 November 2015
PDF: 7 pages
Proc. SPIE 9809, Twelfth International Conference on Correlation Optics, 98090T (30 November 2015); doi: 10.1117/12.2228586

Published in SPIE Proceedings Vol. 9809:
Twelfth International Conference on Correlation Optics
Oleg V. Angelsky, Editor(s)