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

Abstract

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.

Ligand Effects in Assembly of Cubic and Spherical Nanocrystals: Applications to Packing of Perovskite Nanocubes

“…In contrast with spherical NCs, where the breakdown of the hard sphere representation is spontaneous and occurs at low coordination, , in cubes, vertices and edges provide explicit sites for the appearance of vortices; see Figure . Although the precise formulation of the OTM to many relevant shapes ,,− is beyond the scope of this work, the same assumptions used to derive the effective cube sizes (see eq and eq ) also apply to these more complex shapes and the emergence of splayed ligand configurations (vortices) at edges and vertices is therefore a general NC effect.…”

“…This study is explicitly performed for cubes, but the arguments, which are summarized in Figure and Figure , are general and apply to any other shapes, for example. ,,− Our own work ref considered, in addition to cubes, truncated cubes and disks with different shapes, which assemble into diverse superlattices.…”

Molecular Engineering of Colloidal Atoms

“…Reproduced with permission. [ 165 ] Copyright 2022, Springer Nature. c) Copolymer‐mediated site‐selective assembly of plate‐like and sphere‐like nanoparticles into edge‐type and face‐type colloidal molecules.…”

Do chemists control plane packing, i.e. two-dimensional self-assembly, at all scales?

“…47 Such anisotropic functionalization of nanoobjects has already been reported, e.g. on nanorods by differential functionalization of different crystalline face, 48 on isotropic nanoparticles by phase segregation of ligands at their surface or by differential densities, 49,50 or even on triangular gold nanoparticles by asymmetric polymer grafting on the apexes, 51 but no well-organized 2D porous arrays have been reported with these systems. There is therefore a clear space for research in this perspective.…”