Elasticity-mediated Morphogenesis in Interfacial Colloidal Assemblies

TL;DR

This study investigates how particle elasticity influences the self-assembly and structural organization of colloidal microgel particles at an air-water interface, revealing a transition from crystallization to gelation.

Contribution

It demonstrates that particle elasticity is a crucial parameter controlling non-equilibrium colloidal morphogenesis at interfaces, supported by experimental and simulation evidence.

Findings

Increased elasticity shifts assembly from crystallization to gelation.

Diverse metastable structures observed include clusters, voids, and anisotropic aggregates.

Simulations replicate experimental morphologies, highlighting key interaction roles.

Abstract

We study the self-assembly of colloidal microgel particles at a quasi-two-dimensional air-water interface of a drying droplet. Using bright-field microscopy, we demonstrate that increasing particle elasticity drives interfacial organization from repulsion-stabilized crystallization to attraction-dominated gelation, via diverse metastable structures including clusters, voids and anisotropic aggregates. Molecular dynamics simulations using an effective potential that captures the interplay between hydrophobic, capillary, steric and dipolar interactions, reproduce the overall phenomenology of the observed colloidal morphogenesis. Our findings establish particle elasticity as a key parameter governing non-equilibrium structural organization of colloids at an interface.