Alignment of high-aspect ratio colloidal gold nanoplatelets in nematic liquid crystals

Abstract

We study elasticity-mediated alignment of anisotropic gold colloids in liquid crystals. Colloidal gold particles of controlled shapes (spheres, rods, and polygonal platelets) and sizes are prepared using well-established biosynthesis techniques with varying solvent conditions. When introduced into liquid crystalline structured solvents, these gold particles impose tangential or vertical surface boundary conditions for the liquid crystal molecules or building blocks such as chromonic molecular aggregates. This allows for multiple types of their controlled alignment in both lyotropic and thermotropic liquid crystals and is of interest for self-assembly-based fabrication of tunable nanostructured composite materials. V

Elasticity-dependent self-assembly of micro-templated chromonic liquid crystal films

“…43,44 Additionally, the patterns and order induced in theses LCLC films could be transferred to suspended colloids, suspended nanotubes and bacterial systems to create novel metamaterial films. [21][22][23][24][25] …”

“…As a result, their mesophases differ significantly from thermotropic and amphiphilic lyotropic liquid crystals. Patterned films of LCLCs have a wide variety of emerging applications distinct from other types of liquid crystals, including inexpensive polarizing films, [12][13][14] holographic displays, 15,16 organic electronics and solar cells, 17,18 biosensors, 19,20 , aqueous colloidal, nanotube and bacterial assembly, [21][22][23][24][25] and precursors to structured graphene-based materials. 26,27 LCLCs also offer useful attributes for fundamental investigation of the effects of elasticity on self-assembly behavior, since their elastic properties can be tuned via control of mesogen concentration, 28 depletants and ions.…”

Active Shape-Morphing Elastomeric Colloids in Short-Pitch Cholesteric Liquid Crystals

“…Within a far-field approximation, even spherical particles with strong boundary conditions induce dipolar or quadrupolar n(r)-distortions arising due to the anisotropic nature of the host medium and particle-induced satellite defects, such as point defects and disclination loops [1,2]. Although many methods for self-assembly of anisotropic particles in isotropic solvents have been introduced [4], LC hosts bring a number of unique capabilities, such as the well-defined long-range alignment of anisotropic particles with respect to n controlled by external fields [3,[5][6][7][8][9][10].…”

“…Along with symmetry considerations, this brings about an expansion into multipole series and electrostatic analogies between long-distance colloidal interactions and that of multipoles in electrostatics [1][2][3][4][5][6][7][8][9][10][11]36]. The ground state in a CLC is strongly twisted and a direct parallel with the homogeneous nematic ground state is impossible because homogeneity of the ground state is a prerequisite of the symmetry-based considerations [11].…”

“…Shape of particles dictates colloidal self-assembly [3,[7][8][9][10][11][12][13][14][15] and may enable practical utility of these fascinating LC-colloidal systems. Although complex-shaped particles can be fabricated using photolithography [3,6], two-photon polymerization [10], nanocrystal growth [8], and wet chemical synthesis [7,9], these approaches provide nematic dispersions of non-responsive particles with no means for altering their shape, alignment, locomotion, and self-assembly [3,[5][6][7][8].…”