Hybrid Well-Defined Stimuli-Responsive Materials

NON-TECHNICAL SUMMARY With support from the Solid State and Materials Chemistry Program in NSF's Division of Materials Research, this project focuses on achieving fast and reversible control over the switching properties of stimuli-responsive materials. These properties are critical for developing and advancing a broad spectrum of current technologies, ranging from ultra-efficient, high-speed optoelectronics to photochromic catalysis and on-demand drug delivery systems. This project provides an understanding of fundamental principles behind the synthesis of materials with light-responsive building blocks, allowing control of their properties. The well-defined light-responsive materials proposed in this project enable such control by leveraging their cooperative response to external light sources, which allows for the precise switching of material properties. Besides fundamental impacts, this research program integrates workforce development and educational opportunities for a broad range of students, including, but not limited to, high school, graduate, and undergraduate students. TECHNICAL SUMMARY The synthesis of well-defined stimuli-responsive materials whose photophysical properties can be controlled orthogonally or cooperatively is driven by a wide range of applications, including the next generation of sensors, “smart” capacitors, heterogeneous photocatalysts, self-healing and recyclable materials, and artificial muscles. Despite the great interest in this class of materials, the fundamental principles that enable fast and reversible photoisomerization kinetics controlled orthogonally or cooperatively under one or multiple external stimuli such as light and/or heat are still underdeveloped. With support from the Solid State and Materials Chemistry Program in NSF's Division of Materials Research, this work is focused on the primary scientific challenge of developing synthetic methodologies for preparing stimuli-responsive materials incorporating one or two photochromic moieties with rapid and adaptive photoisomerization kinetics. The preparation of materials that allow for (a) integration of distinct classes of photochromic linkers within the same platform, (b) facilitation of reversible isomerization of sterically demanding photochromic moieties due to intrinsic tailorable voids, (c) pore evacuation to enhance photoisomerization kinetics and rapid material response, and (d) precise tuning the photophysical properties through the use of orthogonal external stimuli will be carried out. 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.