Structural diversity in binary superlattices self-assembled from polymer-grafted nanocrystals

Matthew R Hauwiller,Peter Ercius,Xingchen Ye,A Paul Alivisatos,Yi Liu,Chenhui Zhu,Bo He,Ting Xu,Shilpa N Raja,Matthew R Jones

doi:10.1038/ncomms10052

Abstract

Multicomponent nanocrystal superlattices represent an interesting class of material that derives emergent properties from mesoscale structure, yet their programmability can be limited by the alkyl-chain-based ligands decorating the surfaces of the constituent nanocrystals. Polymeric ligands offer distinct advantages, as they allow for more precise tuning of the effective size and ‘interaction softness' through changes to the polymer's molecular weight, chemical nature, architecture, persistence length and surrounding solvent. Here we show the formation of 10 different binary nanocrystal superlattices (BNSLs) with both two- and three-dimensional order through independent adjustment of the core size of spherical nanocrystals and the molecular weight of densely grafted polystyrene ligands. These polymer-brush-based ligands introduce new energetic contributions to the interparticle potential that stabilizes various BNSL phases across a range of length scales and interparticle spacings. Our study opens the door for nanocrystals to become modular elements in the design of functional particle brush solids with controlled nanoscale interfaces and mesostructures.

Highlights

Multicomponent nanocrystal superlattices represent an interesting class of material that derives emergent properties from mesoscale structure, yet their programmability can be limited by the alkyl-chain-based ligands decorating the surfaces of the constituent nanocrystals
These results allow us to access a set of modular building blocks from which a desired binary nanocrystal superlattices (BNSLs) phase can be created via rational choice of NC component
Distinct from alkyl-chainbased ligands, one unique advantage of using polymeric ligands is that the interparticle spacing can be predicted and experimentally accessed with high precision ranging from one to several tens of nanometres, which can be important for tailoring magnetic dipolar coupling[36], plasmonic coupling[37,38] and energy transfer mediated by dipole–dipole interactions within NC assemblies[39]

Summary

Introduction

Multicomponent nanocrystal superlattices represent an interesting class of material that derives emergent properties from mesoscale structure, yet their programmability can be limited by the alkyl-chain-based ligands decorating the surfaces of the constituent nanocrystals. We show the formation of 10 different binary nanocrystal superlattices (BNSLs) with both twoand three-dimensional order through independent adjustment of the core size of spherical nanocrystals and the molecular weight of densely grafted polystyrene ligands. These polymer-brush-based ligands introduce new energetic contributions to the interparticle potential that stabilizes various BNSL phases across a range of length scales and interparticle spacings. Grafting polymers onto NCs introduces new energetic contributions arising from polymer chain conformational entropy and interaction enthalpy These energetic contributions can be readily tailored by the control of the polymer’s molecular weight, chemical nature, architecture, persistence length and surrounding solvent. Distinct from alkyl-chainbased ligands, one unique advantage of using polymeric ligands is that the interparticle spacing can be predicted and experimentally accessed with high precision ranging from one to several tens of nanometres, which can be important for tailoring magnetic dipolar coupling[36], plasmonic coupling[37,38] and energy transfer mediated by dipole–dipole interactions within NC assemblies[39]

Methods

Results

Conclusion