Shape-dependent oriented trapping and scaffolding of plasmonic nanoparticles by topological defects for self-assembly of colloidal dimers in liquid crystals

TL;DR

This paper explores how topological defects in liquid crystals can be used to precisely position and orient plasmonic nanoparticles of various shapes, enabling controlled self-assembly of complex colloidal structures.

Contribution

It introduces a method to scaffold anisotropic plasmonic nanoparticles using topological defects for directed self-assembly in liquid crystals, highlighting shape-dependent trapping and orientation.

Findings

Nanoparticles localize and orient at defects based on shape.

Hierarchical structures like chains and arrays can be self-assembled.

Elastic binding strength can be probed with laser tweezers.

Abstract

We demonstrate scaffolding of plasmonic nanoparticles by topological defects induced by colloidal microspheres to match their surface boundary conditions with a uniform far-field alignment in a liquid crystal host. Displacing energetically costly liquid crystal regions of reduced order, anisotropic nanoparticles with concave or convex shapes not only stably localize in defects but also self-orient with respect to the microsphere surface. Using laser tweezers, we manipulate the ensuing nanoparticle-microsphere colloidal dimers, probing the strength of elastic binding and demonstrating self-assembly of hierarchical colloidal superstructures such as chains and arrays.