Periodic Reporting for period 1 - IMAGINE_LC (Investigating the Manipulation of Alignment/Activity via Geometrical INteraction Effects in Liquid Crystals)
Reporting period: 2023-01-01 to 2024-12-31
Over the last half-century liquid crystals have become a ubiquitous part of daily life due to how they revolutionized the modern display industry. Most common liquid crystals are made of rod-like components (mesogens) that self-assemble, with the simplest liquid crystal phase, nematic, assembling its rod components to generate long-range orientational order. This in turn gives rise to anisotropic properties. For instance, their dielectric and optical anisotropy facilitates their reorientation with applied electric fields and subsequent alteration of light intensity – essential for making a pixel, amongst other liquid crystal technologies. Nematic ordering can occur across length scales from nanometric, molecular systems to centimeter-scale, rod-shaped wires. Indeed, although most people associate liquid crystals with displays, they are also pervasive in larger scaled, living systems. Liquid crystals can even be found within our bodies, such as in the organization of proteins and cells. Recent research aims to apply liquid crystal physics to active, biological systems, to better understand how anisotropy influences function. Yet, the tools developed for the display industry to structure liquid crystals remain to be leveraged for active liquid crystal systems. To advance our understanding of active liquid crystals, essential for elucidating biological processes, I will carry out this fellowship to develop a model liquid crystal system that can be structured through confinement, using techniques inspired by display technologies. My experimental system will probe the impact of geometry on liquid crystal alignment and dynamics. This project will be performed at Utrecht University (UU) under the supervision of Dr. Lisa Tran. The Tran group expertise includes control of molecular liquid crystals under varying geometrical confinement. The Tran group is embedded in the Soft Condensed Matter and Biophysics (SCMB) group and the Debye Institute for Nanomaterials Science, with expertise in nano/micro particle synthesis and high-resolution imaging techniques. Combined with my multi-disciplinary background in liquid crystal physics, chemistry, and engineering, I will innovate the geometrical alignment of passive and active liquid crystals beyond current state of the art.
Colloidal rods of varying aspect ratios and that are trackable with confocal microscopy were successfully synthesized and used to form both a nematic liquid crystal phase and a smectic phase. These colloidal liquid crystals were confined into wells using soft contact photo lithography. Two different confinement geometries were studied: a family of ellipses and walls with topographical features. Active colloidal rods were also synthesized, and a light responsive, colloidal liquid crystal was formed.
In this project, we have mapped out the geometric parameters of the patterned boundary that dictate the transition between planar and homeotropic anchoring, relevant for liquid crystals across length scales. The work has been shared in an open access publication and code developed for particle tracking and defect characterisation has been published in an open access repository.