Interfaces between metal coordinating proteins and inorganic surfaces have a vital role in the mechanical properties of some of the most remarkable composites found in nature. From the underwater adhesive glues of mussels to the tough shells of nacre, sticky interactions between metal binding proteins and inorganic surfaces have increasingly been found to control their mechanical properties. A simpler, synthetic system, where inorganic nanoparticles serve as dynamic bridges for metal binding polymers, will be investigated to learn principles of composite material design from nature and to apply these principles for engineering new materials with controlled and responsive mechanical properties. Potential applications for these materials include drug delivery, self-healing composites, and 3D printing. The PIs will develop learning modules based on these bio-inspired composites for use in outreach activities to increase public awareness about nanotechnology and to recruit more students into STEM careers.
The goal of this project is to utilize bio-inspired metal coordinating polymer-nanoparticle (MCP-NP) composites as model systems for understanding how to engineer novel mechanics via controlled MCP-NP interfacial dynamics. In contrast to previous MCP materials with metal ion crosslinkers, NPs will serve as supramolecular crosslinkers, with a tunable number of ligands bound per NP. Chemical and physical parameters of the system will be adjusted to obtain a fundamental understanding of how molecular interactions at MCP-NP interfaces affect the bulk mechanical properties of MCP-NP composites and to demonstrate control over the mechanical response. In comparison with traditional engineering composites and other composite hydrogels, MCP-NP composites are viscoelastic and have tunable interfacial bonding. Magnetically and optically responsive NPs have been selected to also allow remote heating using light and magnetic fields. This project will provide a deeper understanding of composite interfacial dynamics critical for improved engineering of composite mechanical properties, such as self-healing and tunable fluid-solid transitions. Insights about the relationship between chemistry at MCP-NP interfaces and the mechanical response will be applicable to other composite systems with dynamic interfaces.
