The fundamental tenet of nanoscience is that new properties arise in materials when at least one dimension is smaller than 100 nm. Whereas most examples of this phenomenon relate to size-dependent optoelectronic properties, mechanical forces also show scaling relationships that suggest dramatically different behavior in small particle systems. For example, the energy required for elastic deformation shows a power law dependence on the material thickness, indicating that thin inorganic nanostructures are, in fact, quite malleable, and amenable to novel methods of structure manipulation by ostensibly weak nanoscale forces. In this talk I will discuss recent work from my group which demonstrates the ability for surface ligand chemistry, which is ubiquitous in colloidal nanoscience, to control the mechanical properties of inorganic nanoparticles and drive reconfigurable shape changes via intentional deformation. More specifically, I will show that an increasing coordinating strength of surface-bound ligands results in a rigidification of surface metal atoms in silver nanostructures. When particles are sufficiently thin and have a high ratio of surface to bulk atoms, this results in measurable changes to the mechanical properties of the nanostructure overall. We leverage this understanding to create new curvilinear morphologies from nanoparticle building blocks and show the ability to alter particle shape through ligand chemistry. This kind of coupling between mechanical and chemical forces is rarely explored in inorganic nanostructures but challenges conventional depictions of inorganic nanoparticles as static objects and instead highlights the possibility for novel methods of structure and property control via mechanochemical actuation.

Ligand-derived nanoparticle mechanochemistry

ACS Fall 2021

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