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CHAPTER 6
Hierarchically Organized Systems
Based on Liquid Crystalline Phases
CHANDRASHEKHAR V. KULKARNI and OTTO GLATTER
Department of Chemistry, University of Graz, Graz, Austria
Abstract
In this chapter, we present hierarchically organized nanostructures formed from lyo-
tropic liquid crystalline (LC) phases. The nano-, micro-, and macroscopic structural
hierarchy arises from the kinetic stability of various lyotropic phases dispersed in oil-
in - water (O/W) or water - in - oil (W/O) emulsions. When an O/W emulsion consists of
a dispersion of LC nanoparticles stabilized by certain stabilizers, it is called an ISAsome,
that is, an internally self-assembled particle. In contrast, when the water droplets are
dispersed in a continuous fi lm of LC nanostructures, they are called W/O-nanostructured
emulsions, which do not require a stabilizing agent. Both emulsions exhibit fascinating
properties that can be tuned to a great extent. Such tunability proliferates their per-
formance in various applications. Herein, we discuss the formation, multiscale structure,
properties, and their modulation for the aforementioned superstructures formed from
LC phases. Focusing further on ISAsomes we present Pickering emulsions stabilized
by using various nanoparticles, including synthetic clay Laponite and silica nanopar-
ticles. The transfer of hydrophobic components among several differently nanostruc-
tured ISAsomes was studied by time-resolved X-ray scattering; the effects of
Isasome-forming components are also illustrated. The continuous aqueous region of
ISAsome dispersions can be loaded with water-soluble polymers that form thermorev-
ersible hydrogels. This enables the entrapment of ISAsome systems into such hydrogel
networks. Subsequent drying of these loaded systems facilitates immobilization of
ISAsomes, which can be easily restored by rehydration of the loaded dry fi lms. The
formation of hydrogels in the aqueous reservoirs of W/O-nanostructured emulsions
also proved advantageous in terms of tuning their viscosity and, in some cases, enhanc-
ing their stability. The current contribution covers systems with diverse structural
hierarchy, ranging from equilibrium liquid crystalline nanostructures to the systems
with multiple orders of length scales in their structure.
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