(115e) Threading the Thermodynamic Needle - Balancing Enthalpy and Entropy to Design Complex and Reconfigurable Assemblies

Designing nanoscale synthons with predictive control over shape, size, and interparticle interactions is a holy grail for materials design. To date, there exists a large space of experimental parameters that can be employed to direct nanoscale assemblies. Tuning such experimental handles produces different modes of interactions such as hard particle packing, soft deformable ligand shells, or patchy/selective attraction. However, a major limitation intrinsic to such building blocks lies in the fixed nature of their pre-programmed interactions. This means that the assembled morphologies are also often static, thereby limiting the a priori design of reconfigurable structures. Here, we present strategies for designing building blocks that address the above limitation. We first discuss theoretical insights into how to imbue secondary interactions into synthesized building blocks that can be toggled on/off via experimentally relevant external stimuli such as temperature, external field, and/or solvent change. We then showcase how synthon reconfigurability shifts the preferred, thermodynamically stable assembly structures, validated by both simulation and experiments. Our works provide unique insights into nanoscale synthesis, allowing for a priori design of complex building blocks that can target novel and reconfigurable assemblies.