5 research outputs found
Myelin Structures Formed by Thermotropic Smectic Liquid Crystals
We report on transient
structures, formed by thermotropic smectic-A
liquid crystals, resembling the myelin figures of lyotropic lamellar
liquid crystals. The thermotropic myelin structures form during the
solubilization of a smectic-A droplet in an aqueous phase containing
a cationic surfactant at concentrations above the critical micelle
concentration. Similar to the lyotropic myelin figures, the thermotropic
myelins appear in an optical microscope as flexible tubelike structures
growing at the smectic/aqueous interface. Polarizing microscopy and
confocal fluorescence microscopy show that the smectic layers are
parallel to the tube surface and form a cylindrically bent arrangement
around a central line defect in the tube. We study the growth behavior
of this new type of myelins and discuss similarities to and differences
from the classical lyotropic myelin figures
Solubilization of Thermotropic Liquid Crystal Compounds in Aqueous Surfactant Solutions
We study the micellar solubilization of three thermotropic
liquid
crystal compounds by immersing single drops in aqueous solutions of
the ionic surfactant tetradecyltrimethylammonium bromide. For both
nematic and isotropic drops, we observe a linear decrease of the drop
size with time as well as convective flows and self-propelled motions.
The solubilization is accompanied by the appearance of small aqueous
droplets within the nematic or isotropic drop. At low temperatures,
nematic drops expell small nematic droplets into the aqueous environment.
Smectic drops show the spontaneous formation of filament-like structures
which resemble the myelin figures observed in lyotropic lamellar systems.
In all cases, the liquid crystal drops become completely solubilized,
provided the weight fraction of the liquid crystal in the system is
not larger than a few percent. The solubilization of the liquid crystal
drops is compared with earlier studies of the solubilization of alkanes
in ionic surfactant solutions
Solubilization of Thermotropic Liquid Crystal Compounds in Aqueous Surfactant Solutions
We study the micellar solubilization of three thermotropic
liquid
crystal compounds by immersing single drops in aqueous solutions of
the ionic surfactant tetradecyltrimethylammonium bromide. For both
nematic and isotropic drops, we observe a linear decrease of the drop
size with time as well as convective flows and self-propelled motions.
The solubilization is accompanied by the appearance of small aqueous
droplets within the nematic or isotropic drop. At low temperatures,
nematic drops expell small nematic droplets into the aqueous environment.
Smectic drops show the spontaneous formation of filament-like structures
which resemble the myelin figures observed in lyotropic lamellar systems.
In all cases, the liquid crystal drops become completely solubilized,
provided the weight fraction of the liquid crystal in the system is
not larger than a few percent. The solubilization of the liquid crystal
drops is compared with earlier studies of the solubilization of alkanes
in ionic surfactant solutions
Direct Visualization of Spatiotemporal Structure of Self-Assembled Colloidal Particles in Electrohydrodynamic Flow of a Nematic Liquid Crystal
Characterization of spatiotemporal
dynamics is of vital importance
to soft matter systems far from equilibrium. Using a confocal laser
scanning microscopy, we directly reveal three-dimensional motion of
surface-modified particles in the electrohydrodynamic convection of
a nematic liquid crystal. Particularly, visualizing a caterpillar-like
motion of a self-assembled colloidal chain demonstrates the mechanism
of the persistent transport enabled by the elastic, electric, and
hydrodynamic contributions. We also precisely show how the particles’
trajectory is spatially modified by simply changing the surface boundary
condition
Direct Visualization of Spatiotemporal Structure of Self-Assembled Colloidal Particles in Electrohydrodynamic Flow of a Nematic Liquid Crystal
Characterization of spatiotemporal
dynamics is of vital importance
to soft matter systems far from equilibrium. Using a confocal laser
scanning microscopy, we directly reveal three-dimensional motion of
surface-modified particles in the electrohydrodynamic convection of
a nematic liquid crystal. Particularly, visualizing a caterpillar-like
motion of a self-assembled colloidal chain demonstrates the mechanism
of the persistent transport enabled by the elastic, electric, and
hydrodynamic contributions. We also precisely show how the particles’
trajectory is spatially modified by simply changing the surface boundary
condition