Soft materials that can dramatically change size, shape from two-dimensional (2D) to three-dimensional (3D), volume, and physical properties in response to external stimuli are of great interest for a wide range of potential applications. Plants can achieve complex responsive morphing via a pre-programmed anisotropic deformation of cell walls, which are made of hierarchically arranged fibrous polymers of different stiffness. This project aims to mimic the cell wall structures and functions by programming the anisotropy in fibrous polymers, while exploring molecular heterogeneity and phase separation that are ubiquitous in biology. The research will foster synergistic interactions across disciplines of polymer science and engineering, soft matter physics, and mechanical engineering to develop complex, multi-component, multi-phased networks. The research outcome will lead to potential applications in next generation smart sensors, actuators, soft robots, smart wearables, and 3D displays. It will also act as an effective tool to recruit and train students at all levels. Special emphasis will be given to underrepresented groups to carry out research on campus. The latest research results will be showcased at the Philadelphia Materials Day and Penn Science CafÃ© Program. Shape morphing and reshaping of the polymer networks will create a significant outreach opportunity to excite the general public, thereby provoking and engaging interest in Science, Technology, Engineering, and Mathematics (STEM). A symposium will be organized to feature research outcome and facilitate interactions with researchers from academic, industrial and national labs.
The planned research is based on multi-pronged activities, including design, synthesis, assembly, fabrication, characterization, and property optimization of a unique set of environmentally responsive polymers. These are liquid crystal elastomers and their composites in the form of fibers with precisely controlled compositions, molecular orientations, architectures and mechanical responses from nano- to macroscales. Importantly, the research will offer a holistic view on how to dynamically configure the materialâ€™s intrinsic properties at the molecular level, that is chemical composition, phase separation, and crosslinking gradient, while keeping sights of geometric controls at the micro- to macroscale in the form of cylindrical confinement. The multi-component, multi-phased networks will broaden the materials palette to create more complex structures with precisely controlled anisotropy in material elasticity. Complex shapes in response to an external stimulus will be created to mimic plant cell wall structures and functions, with bonuses such as tunable photonic colors and mechanical adaptivity. The research outcome will enrich fundamental knowledge that relates the locally controllable degrees of freedom to the global geometries, shapes and shapeshifting paths. The insights could contribute to the development of the next generation composite fibers for potential applications such as smart sensors, actuators, 3D displays, soft robots, and smart textiles. .
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.