Nanoparticle self-assembly is a powerful method of building materials with precisely architected structures at the molecular to micrometer length scales. In particular, self-assembled nanoparticle superlattices — three-dimensional ordered arrays of nanoparticles — have been the subject of significant interest due to their emergent properties that arise from the ordering of their nanoparticle building blocks. As a result, these nanoparticles superlattices are promising materials for a variety of applications, from optoelectronics to energy storage. While significant efforts have been made on understanding and controlling the formation of these nanoparticle superlattices, investigations on their mechanical properties are scarce. As the mechanical properties of a material impacts its processing and its suitability for a given application, it is critical that we understand the mechanical behavior of these self-assembled nanoparticle superlattices and develop chemistries to control them.<br/><br/>Here, we discuss how the self-assembly chemistry and superlattice structure impacts the mechanical behavior of these nanoparticle superlattices. Nanocomposite tectons (NCTs), a recently developed nanoparticle superlattice system that uses polymer brush particles functionalized with supramolecular binding groups to drive assembly, are ideal for exploring these parameters as the strength of the supramolecular interactions and the superlattice structure can be easily tuned. In-situ uniaxial compression of substrate-grown hydrogen-bonded nanoparticle superlattices show that these materials undergo significant plastic deformation with an associated loss of nanoparticle ordering. Our systematic nanomechanical experiments, performed to various compression states (up to 50% strain), shed light on the mechanisms of deformation as well as the evolution of properties such as Young’s modulus and yield strength. By modulating the strength of the nanoparticle interactions, via the use of different supramolecular binding groups or covalent bonds, we show that the mechanical properties and deformation behavior of these nanoparticle superlattices can be controlled. The impact of superlattice crystal structure on the mechanical properties are also discussed. These observations provide a more general understanding of how self-assembly chemistry and superlattice structure can be used to control the mechanical properties of these nanoparticle superlattices.

Mechanical properties and deformation behavior of self-assembled nanoparticle superlattices

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.