Photoisomerization-controlled phase segregation in a submicron confined azonematic liquid crystal.

Deuteron nuclear magnetic resonance is used to study the phase segregation behavior of photoisomerizable liquid crystal diheptylazobenzene (7AB) confined into cylindrical pores of Anopore membranes. It is demonstrated that the concentration of both components in a binary trans-7AB and cis-7AB mixture can be controlled dynamically using UV-illumination stimulated trans-to-cis photoisomerization and thermally induced cis-to-trans backisomerization. The so far elusive temperature-concentration phase diagram of such system is determined by comparative analysis of the behavior in bulk, thin-planar, and Anopore-confining geometry.