CAREER: Crystallization of Chiral Liquid Crystals Under Curved Confinement

University Of South Carolina At Columbia, Columbia SC

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). NON-TECHNICAL ABSTRACT Liquid crystals, with properties between conventional liquids and crystalline solids and facile electric response, are the heart of many displays and electro-optic technologies. However, the advent of miniaturized, curved, and flexible devices such as displays, fiber optics, or wearable sensors has created a significant knowledge gap as crystallization under curved confinement remains less well-understood. This project combines experimental and computational studies to discover the governing mechanisms by which high chirality liquid crystals reconfigure their 3D crystal lattices to adapt to curved confined boundaries. These basic nanoscale physical processes underlie a range of macroscopic phenomena, including response time and photonic bandgap, which can be utilized to expand the applications of soft chiral liquid crystals from photonics, sensing, and electronic displays to information technologies. PI combines this research with synergistic educational and outreach activities, including research training for students from minority-serving institutions, curriculum development, and organizing a regional “Soft Matter Workshop” to enhance the exposure of the broader scientific community to soft condensed matter. TECHNICAL ABSTRACT Blue phases (BPs) are chiral liquid crystals with submicron cubic-crystalline lattices that exhibit Bragg refraction of visible light and short coherent length, enabling fast response times of <1 ms, making them attractive for display, photonics, and sensing applications. Geometrical incompatibility between the three-dimensional cubic lattice structure of BPs and curvature can constrain the organization of these nanostructures within curved confined spaces, which can lead to structural instability and the emergence of topological defects. In this project, top-down fabrication strategies are employed to systematically confine BP soft crystals in well-defined curved geometries and tailor the self-assembly of chiral entities over multiple length scales. Moreover, reshaping the BP lattices through interactions with electric fields and mechanical forces are examined, which may enrich the means of controlling the light bandgap of BPs in curved geometries. This work advances our fundamental understanding of the mechanism by which BP 3D crystalline lattices deform, contract, and reconfigure to adapt to the curvature of the bounding surfaces and respond to the environment. Moreover, it provides a foundation for understanding and developing design principles of complex skyrmion structures, which may appear in chiral materials under strong curved confinement. Understanding the fundamental underpinnings of this “curvature-guided” self-assembly and crystal growth may catalyze the use of tailored BP soft nanocrystals and enable the development of new fast-response materials with unique properties needed for practical devices, such as flexible displays, wearable sensors, and information storage devices. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.