Phototuning the Properties of Liquid Crystals

Non-Technical Summary: With support from the Solid State and Materials Chemistry program in the Division of Materials Research, the Aprahamian group investigates the nature of the interaction between a pinch of light-sensitive additives, called switchable molecules, and spiral structures made of liquid crystals - the active components in Liquid Crystal Displays (LCDs). The research focuses on gaining important insights into how the switchable molecules can control the color reflected from the liquid crystal surface. Understanding and harnessing this capability opens the door to the development of different types of low-energy-consuming devices and applications such as smart price tags, anti-counterfeit and cryptography devices, and even adaptive camouflage material. To help disseminate this research and its outcomes with broad audiences, Aprahamian and his group engage in educational and outreach activities, such as the National Chemistry Week, involving high-school and undergraduate students, and use interactive demonstrations to communicate the societal relevance and benefits of this type of fundamental research. Technical Summary: Tuning the photophysical properties of liquid crystals (LCs) using photoswitchable chiral dopants enables a wide range of applications, including smart tags, low-energy displays, and adaptive bandpass filters. The realization of these technologies depends on a fundamental understanding of how dopants interact with the LC host and how these interactions affect the helical pitch of the chiral LC—an essential determinant of its photophysical behavior. With support from the Solid State and Materials Chemistry program in the Division of Materials Research, the Aprahamian group employs halogen bonding to strengthen the interactions between hydrazone-based dopants and the LC host with the goal of improving the chiral information transfer between them, thus enabling precise tuning of the color reflected from the LC surface. The group also develops new chiral architectures, including macrocyclic hydrazones and C3-symmetric scaffolds such as tribenzotriquinacene, to expand the design space and capabilities available to materials scientists. In parallel, they investigate the potential for using switchable dopants to modulate the reflective properties of ferroelectric LCs. In addition to their research efforts, the Aprahamian group engages in educational and outreach initiatives aimed at broadening the impact of their work and communicating the value of fundamental science to broad audiences. 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.