Self-assembly and crystallisation of indented colloids at a planar wall

TL;DR

This study investigates how indented colloids assemble and crystallize on a planar surface, revealing that they form plastic crystals under certain conditions, with implications for designing complex colloidal structures.

Contribution

It provides experimental and simulation insights into the crystallization behavior of indented colloids and explores conditions for forming various crystal states.

Findings

Indented colloids crystallize less easily than spheres.

Simulations show formation of plastic (rotator) crystals.

Conditions for lower-symmetry crystal states are discussed.

Abstract

We report experimental and simulation studies of the structure of a monolayer of indented ("lock and key") colloids, on a planar surface. On adding a non-absorbing polymer with prescribed radius and volume fraction, depletion interactions are induced between the colloids, with controlled range and strength. For spherical particles, this leads to crystallisation, but the indented colloids crystallise less easily than spheres, in both simulation and experiment. Nevertheless, simulations show that indented colloids do form plastic (rotator) crystals. We discuss the conditions under which this occurs, and the possibilities of lower-symmetry crystal states. We also comment on the kinetic accessibility of these states.