NMR in chiral and achiral smectic phases: Structure, orientational order and dynamics

We have controlled the molecular orientation of nematic and smectic A liquid crystal (LC) phases in a porous anodic aluminium oxide (AAO) film, in which the pore diameter was varied from 20 nm to 100 nm. Surface anchoring to induce planar and homeotropic molecular arrangement was controlled by chemical modification of the AAO inner surface. Direct observation of the molecular orientation of LC phases was performed using grazing incidence X-ray diffraction technique, showing in-plane and out-of-plane molecular orientation, and the corresponding layer orientation. The systematic investigation of LC phases under nanoconfinement will be useful to design various kinds of physicochemical environments to control the orientation of other soft matters.

Direct observation of liquid crystal phases under nanoconfinement: A grazing incidence X-ray diffraction study

Electro-optically active polymer–liquid crystal composites based on ferroelectric liquid crystals and stretched porous polyethylene films were developed. The alignment of ferroelectric liquid crystals incorporated into the porous polyethylene films with average porous diameter of around 200 nm was observed and studied. It was shown experimentally that these samples containing ferroelectric liquid crystals are flexible electro-optical films exhibiting a saturation electric field near 2·107 Vm−1 and a response time of about 30 μs under the action of the saturation field. A simple theoretical model of ferroelectric liquid crystal molecules' complete reorientation in electric fields inside pores of the films has been proposed and confirmed experimentally.

Ferroelectric liquid crystal composites based on the porous stretched polyethylene films

Experimental observations show that the nematic–isotropic (N–I) transition temperature (TNI) and nematic to smectic transition temperature (TNA) for liquid crystal (LC) embedded in solid porous mat...

Theoretical study of nematic to smectic transition in cylindrical porous media

We study the temperature evolution of smectic ordering of 8CB liquid crystal confined to various CPG matrices. The characteristic diameters of matrices ranged from 24 nm to 128 nm. The CPG voids were either left non-treated or were treated with silane. A weakly 1st order N-SmA transition in bulk 8CB, which could be attributed to the Halperin-Lubensky-Ma (HLM) effect, is broadened in confined samples. In confined samples substantial pretransitional anchoring was also observed, particularly in the silane-treated samples.

Aleksander Zidansˇek

Papers

Smectic Ordering of 8CB Liquid Crystal Confined to a Controlled-Pore Glass