Blue-phase templated fabrication of three-dimensional nanostructures for photonic applications

Abstract

A promising approach to the fabrication of materials with nanoscale features is the transfer of liquid-crystalline structure to polymers. However, this has not been achieved in systems with full three-dimensional periodicity. Here we demonstrate the fabrication of self-assembled three-dimensional nanostructures by polymer templating blue phase I, a chiral liquid crystal with cubic symmetry. Blue phase I was photopolymerized and the remaining liquid crystal removed to create a porous free-standing cast, which retains the chiral three-dimensional structure of the blue phase, yet contains no chiral additive molecules. The cast may in turn be used as a hard template for the fabrication of new materials. By refilling the cast with an achiral nematic liquid crystal, we created templated blue phases that have unprecedented thermal stability in the range -125 to 125 °C, and that act as both mirrorless lasers and switchable electro-optic devices. Blue-phase templated materials will facilitate advances in device architectures for photonics applications in particular.

Periodic assembly of nanoparticle arrays in disclinations of cholesteric liquid crystals

“…Such an attraction is energetically favored, as the strongly distorted disclination core region is replaced with the additive (4). The unique templating ability of disclinations has stimulated the exploration of their applications, such as the fabrication of optical materials (11), conductive microwires (12), soft magnets (13), and electrooptical devices (5,14,15).Disclinations in nematic liquid crystals are generally onedimensional structures, as the director pattern repeats itself along the line. When an additive is attracted to the disclination core, two possible morphologies are expected: (i) continuous thread-like assembly, or (ii) a linear array of discrete beads.…”

“…Such an attraction is energetically favored, as the strongly distorted disclination core region is replaced with the additive (4). The unique templating ability of disclinations has stimulated the exploration of their applications, such as the fabrication of optical materials (11), conductive microwires (12), soft magnets (13), and electrooptical devices (5,14,15).…”

Large Colloids in Cholesteric Liquid Crystals

“…Recently, there have been significant advances in the technology of blue phases where polymer-stabilised formulations allow BPs to the used in a practically useful temperature range [8,19]. This holds out the promise of useful application in, e.g., photonics [5,6]. More recently, there has also been interest in nanoparticle stabilisation of BPs [18,38].…”

Functional liquid-crystalline polymers and supramolecular liquid crystals

“…245 The formation of LC gels has also been applied to the preservation of exotic LC phases such as blue phases that have intriguing photonic functions. [246][247][248][249] Remarkably, LC chemical gels also show shape variations in response to temperature and external fields. [250][251][252][253][254][255] Thermal actuation in LC chemical gels is often accompanied by volume variations.…”