Symmetry-breaking in patch formation on triangular gold nanoparticles by asymmetric polymer grafting

Patchy nanoparticles are desirable building blocks for the guided assembly of functional superstructures. Here, the authors demonstrate quantitative control over asymmetric polymer grafting on triangular Au nanoprisms based on polymer scaling theory. Synthesizing patchy particles with predictive control over patch size, shape, placement and number has been highly sought-after for nanoparticle assembly research, but is fraught with challenges. Here we show that polymers can be designed to selectively adsorb onto nanoparticle surfaces already partially coated by other chains to drive the formation of patchy nanoparticles with broken symmetry. In our model system of triangular gold nanoparticles and polystyrene-b-polyacrylic acid patch, single- and double-patch nanoparticles are produced at high yield. These asymmetric single-patch nanoparticles are shown to assemble into self-limited patch-patch connected bowties exhibiting intriguing plasmonic properties. To unveil the mechanism of symmetry-breaking patch formation, we develop a theory that accurately predicts our experimental observations at all scales-from patch patterning on nanoparticles, to the size/shape of the patches, to the particle assemblies driven by patch-patch interactions. Both the experimental strategy and theoretical prediction extend to nanoparticles of other shapes such as octahedra and bipyramids. Our work provides an approach to leverage polymer interactions with nanoscale curved surfaces for asymmetric grafting in nanomaterials engineering.

Automated summary

This study demonstrates quantitative control over asymmetric polymer grafting on triangular Au nanoprisms based on polymer scaling theory. The authors show that polymers can selectively adsorb onto nanoparticle surfaces already partially coated by other chains, resulting in the formation of patchy nanoparticles with broken symmetry. These asymmetric nanoparticles exhibit intriguing plasmonic properties and their formation can be accurately predicted by a developed theory.