Unraveling and controlling the self-assembly pathways of cubic colloids

TL;DR

This study experimentally shows how tuning shape-induced directional bonds in cubic colloids alters their self-assembly pathways, revealing three regimes and enabling pathway control for designing advanced materials.

Contribution

It demonstrates that adjusting attraction strength influences self-assembly pathways of cubic colloids, providing a method to control structure formation.

Findings

Identified three self-assembly regimes: nucleation, dynamic, and static.

Transitions between regimes are reversible and pathway-dependent.

Directional bonding governs pathway selection and structure outcome.

Abstract

The self-assembly of anisotropic building blocks into complex spatial architectures is an important design strategy in material science but the mechanisms by which the anisotropic interactions influence the early-stage growth and formation of disordered (non-)equilibrium structures remain poorly understood. Here, we experimentally demonstrate that tuning the strength of shape-induced directional bonds changes the self-assembly pathways of cubic colloids. By tracking the growth kinetics and internal reorganizations of small clusters at increasing attraction strength, we identify three self-assembly regimes: (i) nucleation and growth regime: slow reorganization-dominated growth of crystalline clusters, (ii) dynamic regime: diffusion-limited growth with dynamic cube reorganizations leading to disordered crystalline clusters and (iii) static regime: diffusion-limited growth of kinetically arrested clusters unable to reorganize due to directional bonding constraints. We further show that transitions between these regimes are reversible and allow pathway engineering to control the structure and disorder. Our results reveal how directional bonding governs pathway selection, providing important insights for the rational design of reconfigurable colloidal, nano-, and biomaterials.