NSF Award
2323483
The goal of the research supported by this Designing Materials to Revolutionize and Engineer our Future (DMREF) award is to design gel materials with controlled mechanical and optical properties. Colloidal gels are bonded, three-dimensional networks of tiny particles (colloids) whose spatial organization and connectivity result in distinctive combinations of properties useful for wide-ranging applications. The project will result in new ways to use computers to simulate and design materials based on their component colloids and their interactions. The investigators will develop soft, processable gels that interact with light in ways typically associated with hard solids and materials that could emulate the mechanical function of natural protein networks to stabilize synthetic cells. Simulation software developed by the team will be shared as open-source code. The award will support the transition of community college students to four-year STEM degree programs through mentorship and summer research experiences.<br/><br/>The dynamic connectivity and organization of gel networks across length scales determine their physical properties, motivating the development of structural design principles applicable to diverse gel compositions. Gels will be assembled from well-defined star-polymers and ligand-functionalized nanocrystals, for which a unified coarse-grained modeling scheme that treats the building blocks as patchy colloids with discrete binding sites will be developed and validated. A linker strategy, in which macromers or nanocrystals are reversibly connected by bifunctional molecules, offers macroscopic control over the number of nearest neighbors and modular tunability of composition, structure, and resulting properties. This strategy and the associated design principles will be advanced to direct the mechanical properties of hydrogels, optical properties of plasmonic nanocrystal gels, and the mechano-optical response of hybrid networks by controlling the phase behavior through modulating linker-to-colloid ratio and properties of the components. The project will leverage recent progress in making and modeling networks with dynamic covalent bonding and in computing the optical response of structurally complex assemblies by considering the mutual polarization of nanoparticle dipoles under resonant excitation. Tight integration of synthesis, assembly, and characterization with theory and modeling will give a full picture of the range of behaviors that can be achieved through use of these hybrid structural motifs.<br/><br/>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.
