Experimental Advances in Nanoparticle-Driven Stabilization of Liquid-Crystalline Blue Phases and Twist-Grain Boundary Phases

Abstract

Recent advances in experimental studies of nanoparticle-driven stabilization of chiral liquid-crystalline phases are highlighted. The stabilization is achieved via the nanoparticles’ assembly in the defect lattices of the soft liquid-crystalline hosts. This is of significant importance for understanding the interactions of nanoparticles with topological defects and for envisioned technological applications. We demonstrate that blue phases are stabilized and twist-grain boundary phases are induced by dispersing surface-functionalized CdSSe quantum dots, spherical Au nanoparticles, as well as MoS2 nanoplatelets and reduced-graphene oxide nanosheets in chiral liquid crystals. Phase diagrams are shown based on calorimetric and optical measurements. Our findings related to the role of the nanoparticle core composition, size, shape, and surface coating on the stabilization effect are presented, followed by an overview of and comparison with other related studies in the literature. Moreover, the key points of the underlying mechanisms are summarized and prospects in the field are briefly discussed.

Mechanical Actuation via Homeomorphic Transformations of Topological Solitons within Polymer Coatings

“…Torons were created by using laser tweezers with a power of 100 mW, as described in refs. [11,12,21]. After generation, the torons were optically manipulated with the laser tweezers at a lower power of the order of 10 mW, remaining stable when spatially translated.…”

“…The utilized laser tweezer setup was built around an inverted optical microscope (IX-81, Olympus) and also comprised a 1064 nm ytterbium-doped fiber laser (YLR-10-1064, IPG Photonics) and a phaseonly spatial light modulator (P512-1064, Boulder Nonlinear Systems), in addition to various lenses and other optical elements described in detail elsewhere. [11,12,21] In some cells, torons were further controlled by applying a 1 kHz AC sinusoidal voltage across the gap between ITO glass substrates using a function generator (DS345, Standford Research Systems).…”

“…In its most simple form, describes a continuous twist to form a helix, [ 11 ] but more spatially distorted structures are possible as well. [ 12 ] In general, the interactions that break the inversion symmetry are weak, and the twisted ground states easily take additional conformations by external fields or surface interactions. For instance, they may lead to particle‐like excitations with skyrmion (2D) or toron‐shaped (3D) internal director patterns of various complexity.…”

Exploring Quantum Dots Size Impact at Phase Diagram and Electrooptical Properties in 8CB Liquid Crystal Soft-Nanocomposites

“…It has been observed that the properties of the LC-host are primarily affected by the geometry of the NPs (size, shape), their bulk and/or surface properties, and their concentration. Over the past two decades, numerous theoretical and experimental studies have been appeared regarding the influence of NPs on phase transitions, orientational order, and the response of the host liquid crystalline matrix to external fields [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Naturally, the well-known Fréedericksz transition has been studied too in certain soft-nanocomposite materials for the voltage threshold of this transition is crucial for applications.…”

Supramolecular Tools for the Stabilisation of Blue-Phase Liquid Crystals

“…Therefore, in the last few decades, a lot of efforts have been made into the stabilisation of BP for making them appealing for application in optoelectronics or photonic sensing. To stabilise the structural features of BPs, and thereby widening the temperature range, different approaches have been followed like the introduction of polymers 11c and nanoparticles (NPs), 14 or by doping with low-molecular weight additives. 15 Polymer stabilisation was first reported by Kikuchi et al who could achieve a BP temperature range of more than 60 °C.…”