Microplate Active Migration Emerging From Light‐Induced Phase Transitions in a Nematic Liquid Crystal

Abstract

Achieving precise control over the diverse equilibrium configurations and corresponding optical textures of motile liquid crystals (LCs) in response to a wide range of external stimuli is a formidable challenge. This complexity becomes even more intriguing when applied to far‐from‐equilibrium systems. In this work, we investigate how LC phase transitions are leveraged to achieve controlled self‐propulsion of colloids. To accomplish that, we designed quasi‐2D solid, micron‐sized, light‐absorbing platelets suspended in a thermotropic nematic LC. When exposed to light, these platelets self‐propel, generating localized nematic‐isotropic (NI) phase transitions. The system's dynamics are governed by temperature, light intensity, and confinement, giving rise to three regimes: a large 2D regime where the platelet‐isotropic phase bubble remains stationary with a stable NI interface; a compact motile‐2D regime where the NI interface is closer to the platelet; and a motile‐3D confinement regime, marked by the appearance of multipolar LC configurations. Furthermore, we employed continuum mean‐field simulations to predict stable platelet‐LC states in slab confinements. The approach gives insights crucial for designing far‐from‐equilibrium synthetic systems with controlled propulsion and tunable topological reconfigurations. This has implications for advancements in photonics and material sciences.