(484f) Assembly of Nanoparticles into Unique Clusters, Strings, Networks, Monolayers, and Bilayers at Interfaces

Many novel applications of polymer nanocomposites require higher-order organization of the embedded nanoparticles (NPs) within the polymer. In this talk, I will discuss a new approach we have proposed for assembling NPs into unique and anisotropic architectures within a polymer matrix. The approach takes advantage of differences in the surface tension between two immiscible polymers forming a bilayer, and those between polymer grafts attached on the particles and the two polymer layers, to trap NPs within 2D planes at tunable distances parallel to the interface. The interactions between multiple NPs trapped in distinct planes can then be used to assemble particles into unique arrangements near the interface. We demonstrate using molecular dynamics (MD) simulations that this approach can be used to assemble spherical NPs into unique clusters, such as tilted dimers and open trimers, as well as unique quasi-1D and 2D architectures, such as serpentine and branched structures, ridged hexagonal monolayers, and square-ordered bilayers.¹ Since MD simulations are very inefficient in determining the equilibrium configuration of NP assemblies involving large numbers of particles, we have developed an efficient basin-hopping Monte Carlo optimization approach for rapidly obtaining the global minimum-energy configurations of such NP assemblies. This strategy is allowing us to explore the full breadth of binary and ternary NP superlattices achievable using our interfacial assembly approach. Lastly, our interfacial assembly approach can also be used to control the orientation and assembly of shaped NPs at the interface. In particular, we have demonstrated the ability to tune the orientation of nanocubes between face-up, edge-up, and vertex-up orientations and to assemble them into rectilinear 1D strings and 2D porous monolayers. Overall, this work suggests that interfacial assembly of NPs could be a promising approach for fabricating next-generation functional materials with potential applications in plasmonics, electronics, optics, and catalysis.

¹ T.Y. Tang, Y. Zhou, and G. Arya. (2019) “Interfacial Assembly of Tunable Anisotropic Nanoparticle Architectures.” ACS Nano 13:4111-4123.