References of "Liang, Hsin-Ling"
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See detailTuneable Multicoloured Patterns From Photonic Cross Communication Between Cholesteric Liquid Crystal Droplets
Noh, Junghyun UL; Liang, Hsin-Ling; Drevensek-Olenik, Irena et al

in Journal of Materials Chemistry C (2014), 2(5), 806-810

Monodisperse droplets of planar-aligned cholesteric (N*) liquid crystal exhibit an intriguing capacity for photonic cross-communication, giving rise to colourful patterns that depend sensitively on the N ... [more ▼]

Monodisperse droplets of planar-aligned cholesteric (N*) liquid crystal exhibit an intriguing capacity for photonic cross-communication, giving rise to colourful patterns that depend sensitively on the N* pitch, droplet positions and illuminated area. The phenomenon results from a combination of omnidirectional selective reflection of N* droplets—which thus act as spherically symmetric self-assembled photonic crystals—and total internal reflection at the continuous phase surface. We outline how the unique optical properties can be employed in numerous applications. [less ▲]

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See detailTowards tunable defect arrangements in smectic liquid crystal shells utilizing the nematic-smectic transition in hybrid-aligned geometries
Liang, Hsin-Ling; Zentel, Rudolf; Rudquist, Per et al

in Soft Matter (2012), 8(20), 5443-5450

We produce and investigate liquid crystal shells with hybrid alignment—planar at one boundary, homeotropic at the other—undergoing a transition between the nematic (N) and smectic-A (SmA) phases. The ... [more ▼]

We produce and investigate liquid crystal shells with hybrid alignment—planar at one boundary, homeotropic at the other—undergoing a transition between the nematic (N) and smectic-A (SmA) phases. The shells display a dynamic sequence of patterns, the details depending on the alignment agents and on the diameter and thickness of the shell. In shells of sufficient diameter we typically find a transient striped texture near the N–SmA transition, stabilising into a pattern of tiled, more or less regularly spaced focal conic domains in the SmA phase. The domain size and spacing decrease with reduced shell thickness. In case of strong homeotropic anchoring at one boundary and small shell size, however, the increased curvature favors homeotropic against planar alignment in the smectic phase, and the shell then tends to adapt to complete homeotropic alignment at the final stage of the transition. This is the first study of hybrid-aligned smectic shells and the results constitute a beautiful demonstration of the capacity for dynamic structure formation and reformation via self-assembly in soft matter. The new patterns extend the range of arrays of topological defects that can be realised with liquid crystals in spherical morphology and the correlation between the feature arrangements and the variable parameters of the shell and its environment opens a route towards tunability. However, the observed strong impact from increasing curvature, even for these rather large shells, indicates that the choice of alignment agents inducing planar or homeotropic alignment with varying strength will become critical when targeting the most attractive colloidal size scale of about a micron or smaller. [less ▲]

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See detailOne-piece micropumps from liquid crystalline core-shell particles
Fleischmann, Eva-Kristina; Liang, Hsin-Ling; Kapernaum, Nadia et al

in Nature Communications (2012), 3

Responsive polymers are low-cost, light weight and flexible, and thus an attractive class of materials for the integration into micromechanical and lab-on-chip systems. Triggered by external stimuli ... [more ▼]

Responsive polymers are low-cost, light weight and flexible, and thus an attractive class of materials for the integration into micromechanical and lab-on-chip systems. Triggered by external stimuli, liquid crystalline elastomers are able to perform mechanical motion and can be utilized as microactuators. Here we present the fabrication of one-piece micropumps from liquid crystalline core-shell elastomer particles via a microfluidic double-emulsion process, the continuous nature of which enables a low-cost and rapid production. The liquid crystalline elastomer shell contains a liquid core, which is reversibly pumped into and out of the particle by actuation of the liquid crystalline shell in a jellyfish-like motion. The liquid crystalline elastomer shells have the potential to be integrated into a microfluidic system as micropumps that do not require additional components, except passive channel connectors and a trigger for actuation. This renders elaborate and high-cost micromachining techniques, which are otherwise required for obtaining microstructures with pump function, unnecessary. [less ▲]

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See detailLiquid Crystals in Novel Geometries prepared by Microfluidics and Electrospinning
Liang, Hsin-Ling; Enz, Eva; Scalia, Giusy et al

in Molecular Crystals & Liquid Crystals (2011), 549

We describe two new techniques of preparing liquid crystal samples and discuss their potential for novel research and applications. Very thin polymer composite fibers func- tionalized by a liquid ... [more ▼]

We describe two new techniques of preparing liquid crystal samples and discuss their potential for novel research and applications. Very thin polymer composite fibers func- tionalized by a liquid crystalline core are realized by coaxial electrospinning of a polymer solution surrounding the liquid crystal during the spinning process. The re- sulting fiber mats exhibit the special properties and responsiveness of the liquid crystal core, e.g. temperature dependent selective reflection when a short-pitch cholesteric is encapsulated. In the second approach an axisymmetric nested capillary microfluidics set-up is used to prepare liquid crystalline shells suspended in an aqueous continuous phase. The spherical geometry of the shell imposes specific defect configurations, the exact result depending on the prevailing liquid crystal phase, the director anchoring conditions at the inner and outer surfaces, and the homogeneity of the shell thickness. With planar director anchoring a variety of defect configurations are possible but for topological reasons the defects must always sum up to a total defect strength of s = +2. Homeotropic anchoring instead gives a defect-free shell, in contrast to a droplet with homeotropic boundary conditions, which must have a defect at its core. By varying the inner and outer fluids as well as the liquid crystal material and temperature, the defect configuration can be tuned in a way that makes the shells interesting e.g. as a versatile colloid crystal building block. [less ▲]

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See detailNematic-smectic transition under confinement in liquid crystalline colloidal shells
Liang, Hsin-Ling; Schymura, Stefan; Rudquist, Per et al

in Physical Review Letters (2011), 106(24), 247801

We carry out the first study of smectic liquid crystalline colloidal shells and investigate how their complex internal structure depends on the director configuration in the nematic phase, preceding the ... [more ▼]

We carry out the first study of smectic liquid crystalline colloidal shells and investigate how their complex internal structure depends on the director configuration in the nematic phase, preceding the smectic phase on cooling. Differences in the free energy cost of director bend and splay give an initial skewed distribution of topological defects in the nematic phase. In the smectic phase, the topological and geometrical constraints of the spherical shell imposed on the developing 1D quasi-long-range order create a conflict that triggers a series of buckling instabilities. Two different characteristic defect patterns arise, one driven by the curvature of the shell, the other by the strong nonuniformities in the director field in the vicinity of the topological defects. [less ▲]

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