Self-assembly and structural relaxation in 'patch-clasping' nanoparticles

Polymer-grafted ‘patchy’ nanoparticles (NPs) can self-assemble into open network structures, making them great building blocks for tunable metamaterials. However, a fundamental understanding of the underlying driving forces remains elusive. Here, we combine simulation and experiments to study the assembly dynamics of a model system of triangular gold nano-prisms functionalized with polystyrene-polyacrylic acid block copolymers (PS-b-PAA). We show that inter-NP bonds formed between interacting polymeric patches are longitudinally robust and rotationally flexible. Scaling theory reveals that inter-NP bond formation is driven by chain reorganization between interacting patches. This enables the development of a coarse-grained model that reproduces experimental dynamics of network chains formed from multiple NPs. Simulations reveal that the network’s rotational relaxation, and therefore reconfiguration, is influenced by chain architecture and relative bond orientations between NPs. Our results suggest that tuning the relative orientations between patchy-NP during bond formation can provide a powerful handle for controlling the dynamical responses of reconfigurable nanomaterials.