Microscopic Observation of Phase Transition Behavior Induced Photochemically in Photoresponsive Liquid Crystals with Azobenzene Derivatives

Abstract

Photochemically induced nematic (N)-to-isotropic (I) phase transition behavior in mixtures of an azobenzene derivative and a host liquid crystal (LC) was observed in the presence of non-mesogenic dopants. On photoirradiation of the mixtures to cause the trans-cis isomerization of azobenzene, the formation of local I domains was observed. When a bent-shaped dopant was added as a non-mesogenic molecule to the mixtures, the I domain formation took place more effectively. The domain formation seems to result from the aggregation of cis isomers, which could be enhanced to more extent with the aid of the bent-shaped dopant with the common structural feature to the cis-azobenzene.