Optical orientation of nematic liquid crystal droplets via photoisomerization of an azodendrimer dopant
نویسندگان
چکیده
Two sequential transformations of the orientational structure in nematic liquid crystal droplets containing a dendrimer additive (nanosized macromolecules with light-absorbing azobenzene terminal moieties) under light irradiation in the UV-blue spectral range were investigated. The origin of these transitions is in the change of the boundary conditions due to photoisomerization of the dendrimer adsorbed onto the liquid crystal-glycerol interface. It was shown that the photoisomerization processes of dendrimer molecules in a liquid crystal are accompanied by a spatial rearrangement of their azobenzene moieties, which is the key point in the explanation of the observed effects.
منابع مشابه
Dynamics of photoinduced changes in birefringence and dichroism in a nematic phase containing an azobenzene as dopant.
Changes in birefringence and dichroism induced by light were monitored after pulse excitation of a nematic phase consisting of a mixture of a low molecular weight liquid crystal (ZLI-1132) and a dopant 4-(N,N-dimethylamino)-azobenzene. After excitation in the UV, large changes in the light transmitted by the sample, placed between polarizers at various angles or in the polarized absorption spec...
متن کاملRotational Diffusion of Monodisperse Liquid Crystal Droplets
many isotropic oils, this liquid crystal is not soluble in water. We therefore We have prepared monodisperse suspensions of nematic liquid use an ionic surfactant, sodium dodecyl sulfate (SDS), to stabilize the crystal droplets in water. The droplets are stabilized by polyvinyl droplets. This allows us to use standard fractionated crystallization methods alcohol, a polymer that induces planar a...
متن کاملPhotochemical switching between colloidal photonic crystals at the nematic-air interface.
A direct observation of the photochemical switching between colloidal crystals with different lattice constants in a liquid-crystal (LC) emulsion is reported. Glycerol droplets introduced in a nematic liquid crystal form two-dimensional hexagonal colloidal crystal at the nematic-air interface with a lattice constant depending on the surface tension sigmaLCA. We dope an azobenzene derivative int...
متن کاملPhotochemical phase transition versus photochemical phase separation.
When a nematic liquid crystal is doped with a large amount of a liquid crystalline azobenzene compound (15 wt %), the photoisomerization of azobenzene under UV and visible light irradiation can give rise to reversible and interconvertible photochemical phase transition and photochemical phase separation. Both normal and reverse modes of photocontrolled switching of transmittance through crossed...
متن کاملNanoparticle self-assembly at the interface of liquid crystal droplets.
Nanoparticles adsorbed at the interface of nematic liquid crystals are known to form ordered structures whose morphology depends on the orientation of the underlying nematic field. The origin of such structures is believed to result from an interplay between the liquid crystal orientation at the particles' surface, the orientation at the liquid crystal's air interface, and the bulk elasticity o...
متن کامل