Stretchable liquid-crystal blue-phase gels

Abstract

Liquid-crystalline polymers are materials of considerable scientific interest and technological value. An important subset of these materials exhibit rubber-like elasticity, combining the optical properties of liquid crystals with the mechanical properties of rubber. Moreover, they exhibit behaviour not seen in either type of material independently, and many of their properties depend crucially on the particular mesophase employed. Such stretchable liquid-crystalline polymers have previously been demonstrated in the nematic, chiral-nematic, and smectic mesophases. Here, we report the fabrication of a stretchable gel of blue phase I, which forms a self-assembled, three-dimensional photonic crystal that remains electro-optically switchable under a moderate applied voltage, and whose optical properties can be manipulated by an applied strain. We also find that, unlike its undistorted counterpart, a mechanically deformed blue phase exhibits a Pockels electro-optic effect, which sets out new theoretical challenges and possibilities for low-voltage electro-optic devices.

Blue-phase liquid crystal droplets

“…In the bulk, however, BPs are only found in a narrow range of temperature, between the cholesteric and the isotropic phases (1-6, 10-18), thereby placing limits on their practical utility. Recent efforts have therefore focused on increasing their stability over wider ranges of temperature and chirality, for example through addition of nanoparticles (19, 20, 21-23), polymers (24-26), or by manipulating their flexoelectricity (14).Confined chiral liquid crystals are of interest for applications in optical devices (27)(28)(29)(30)(31). Simulations of chiral LCs in channels have shown that their defect structure can be manipulated through confinement, thereby raising intriguing prospects for technology (32)(33)(34)(35).…”

“…Confined chiral liquid crystals are of interest for applications in optical devices (27)(28)(29)(30)(31). Simulations of chiral LCs in channels have shown that their defect structure can be manipulated through confinement, thereby raising intriguing prospects for technology (32)(33)(34)(35).…”

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.…”