Hybrid molecular-colloidal liquid crystals

Abstract

Finding order in twos In nematic liquid crystals, the local orientation of the molecules hovers around an average direction. The orientational control bestows unusual optical properties. In theory, with the right sort of two-dimensional shape, it should be possible to create nematics with biaxial ordering, but this has proven elusive. Mundoor et al. dispersed colloidal rods into a nematic solvent (see the Perspective by Poulin). Within a range of temperature and concentration, the rods ordered orthogonally to the solvent molecules, thus giving the mixture the type of properties that one would expect from a biaxial liquid crystal. Science , this issue p. 768 ; see also p. 712

High-order elastic multipoles as colloidal atoms

“…On the other hand, the concept of controlling surface anchoring on spherical constituents of composite colloidal objects that we present here can be extended to patchy particles [7][8][9]54], where different patches can exhibit different boundary conditions, and particles with controlled surface topography [43], surface charging [55] and chemical functionalization [15]. In nematic hosts, these highly tunable multipolar elastic interactions can be further enriched by weakly screened electrostatic monopole-like [56] and magnetic dipolar [57,58] interactions in cases of charged or magnetic particles. The ability of describing elastic, electrostatic and magnetic interactions as multipoles of different nature and order is a useful platform for designing LC colloidal composites.…”

“…Interestingly, in this respect the electrostatic monopoles in LCs have been studied [56] but designing higher order electrostatic multipoles appears to be challenging so far. Differently, magnetic monopoles are considered impossible while dipoles can be easily obtained by using magnetically monodomain particles [57,58].…”

Colloidal interactions and unusual crystallization versus de-mixing of elastic multipoles formed by gold mesoflowers

“…Deviations of n(r) in opposite directions away from the far-field uniform alignment can be interpreted analogously to opposite charges in electrostatic charge distributions, defining the design principles for achieving diverse types of colloidal interactions and assemblies that mimic the well-understood interactions between electrostatic charge distributions 11 . In addition to theoretical analysis [5][6][7][12][13][14][15]17 , a number of elastic multipoles have been discovered experimentally 3,[8][9][10][11][16][17][18][19][20][21] . Surface anchoring boundary conditions on the particles and size, shape, topology and chirality are all found to be important factors, defining behavior of nematic LC colloids 11 .…”

Gold Nanoparticles Thin Films with Thermo‐ and Photoresponsive Plasmonic Properties Realized with Liquid‐Crystalline Ligands

“…Utilization of liquid crystals has been a promising approach . Combining the optical properties of nanoparticles with the structural adaptability of liquid crystal (LC) systems has allowed the development of switchable materials . However, most of these systems are obtained by doping the LC matrix and can only achieve a low metal concentration which limits the plasmonic applications.…”