ERI: Engineering self-assembled responsive materials by employing light-driven shapeshifting of colloidal particles

Microscopic responsive materials that can change their shapes in response to stimuli from the environment have many transformative applications. The current technology of manufacturing responsive microstructures faces significant challenges due to the cost of expensive tools, such as high-resolution 3D printers, and limitation in the diversity of target 3D shapes. This award will investigate the potential of an inexpensive alternative manufacturing method based on self-assembly process. In a self-assembly process, the small building blocks of a material organize themselves into a functional structure without human intervention. By using responsive building blocks, the shape of a self-assembled structure can be reconfigured on demand. Because self-assembly provides access to the material response at a building-block level and the flexibility to assemble and disassemble on demand, it is a promising candidate for solving the engineering challenges of responsive material design at small scales. This award will provide opportunities to train undergraduate and Masters’ students at CSUF (a Hispanic-serving Institution) into highly skilled researchers and future leaders of engineering research. It will also engage the broader community in cutting-edge soft materials research. Colloidal particles that change their shape in response to light will be employed to investigate responsive self-assembly, with a focus on shaping the global structure using local tuning of particle shapes. A new experimental system will be developed that allows for static and dynamic patterned light illumination on colloidal assemblies. The specific goals of this award are (1) to test the hypothesis that ordered colloidal crystals can be shaped through emission and migration of dislocations, and (2) to investigate shapeshifting of disordered colloidal clusters. In addition, a numerical model will be developed to understand the impact of colloidal interaction range and strength on the shapeshifting dynamics. To date, experiments on responsive self-assembly have been studied only in the context of global shape reconfiguration. This award will allow testing of theoretical predictions suggesting that control over local particle shapes will lead to intriguing global behavior with applications in defect engineering, colloidal robotics, and the study of active matter. 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.