Dynamical behavior of a nematic lyotropic liquid crystal in flat confined samples.
We investigate the dynamical behavior of the director in the surface layer of lyotropic nematic liquid crystals in an external magnetic field. The characteristic time of the orientation process is obtained from optical measurements for samples of different thickness (200, 50, and 10 microm). The boundary surfaces are glass plates coated with rubbed polymer [polymethylmethcrylate (PMMA)], to introduce an easy axis. Drastic changes in the dynamical behavior are observed when the thickness is decreased and the experimental results indicate a uniaxial to biaxial transition due to the confinement of the nematic sample.
Bechtold
I H
IH
Instituto de Física, Universidade de São Paulo, São Paulo, P.O. Box 66318, CEP 05315-970, São Paulo, Brazil.
Bonvent
J J
JJ
Oliveira
E A
EA