Dynamic Complex Liquid Crystal Emulsions

Abstract

We report a new class of dynamically reconfigurable complex colloids comprising immiscible liquid crystals (LCs) and fluorocarbon oils. Producing stable spherical droplets requires the utilization of appropriately designed surfactants to reduce the high intrinsic surface tension between the LCs and the fluorocarbon oils that initially lead to non-spherical, "snowman-shaped" Janus droplets. After stabilizing the interfaces via surfactants, the LC droplet morphology can be dynamically switch between LC-in-fluorocarbon-in-water double emulsions (LC/F/W), spherical Janus emulsions, and inverted double emulsions (fluorocarbon-in-LC-in-water, F/LC/W) in response to changes in the surrounding surfactants. These stabilization methods can be extended to smectic LCs to create droplets with more complex internal arrangements and expand the range of LC emulsions that can be prepared. In addition, by using new mesogenic surfactants that control the LC director field at each LC-interface, we prepare LC complex colloids exhibiting different internal configurations. The ability to control the LC anchoring conditions made possible to create topological singularities as powerful templates for the precision assembly of antibodies at the droplets' interface. These dynamic LC complex colloids of controllable morphology and LC orientation are rich soft materials platforms that will find utility in a variety of sensing applications.

Responsive drop method: quantitativein situdetermination of surfactant effectiveness using reconfigurable Janus emulsions

“…the droplet geometries can be controllably altered after emulsification by triggering changes in the surfactant effectiveness, 15,16 and examples of the latter include stimuli-responsive or cleavable surfactants. 17 Owing to this unique morphological response to targeted chemical stimuli, Janus emulsions have been exploited in a number of applications, including as tunable microlenses, 18 optical waveguides, [19][20][21] scaffolds for the fabrication of anisotropic solid objects, 22,23 motile particle systems, 24,25 and as transducers and signal amplifiers in improved chemo-and biosensing platforms. [26][27][28][29] Herein, we leverage the exquisitely sensitive chemicalmorphological coupling inside Janus emulsions for the development of a new simple and broadly applicable method for the quantitative characterization of surfactants.…”

Controlled Movement of Complex Double Emulsions via Interfacially Confined Magnetic Nanoparticles

“…These droplets were obtained by using our previously reported method based on mesogenic surfactants that promote an alternative parallel (planar) LC anchoring at the LC/W interface ( Figure S10 ). 15 Janus monopolar droplets concentrate the MNP-NH 2 assembly at the topological defect at the droplet’s pole. Aldehyde 2 , which is not liquid crystalline, concentrates around the defect core to minimize the free energy and subsequently reacts with MNP-NH 2 at this location.…”

Temperature-induced liquid crystal microdroplet formation in a partially miscible liquid mixture

“…optical properties and stimuli response. [28][29][30][31][32][33][34][35] LC microdroplets embedded in a polymer matrix have attracted considerable interest in optoelectronic applications, such as variable transmittance windows and reflective mode displays. 27,36,37 Solutiondispersed LC droplets are a promising platform for chemo-& biosensing.…”