Engineering azeotropy to optimize the self-assembly of colloidal mixtures

TL;DR

This paper investigates how engineering azeotropic points in patchy particle systems can simplify the self-assembly process of complex structures, enabling the design of multi-component systems that behave as effective one-component systems at specific conditions.

Contribution

It introduces a method to select patchy particle systems with azeotropic points to control and optimize the self-assembly of complex structures, demonstrated with a binary mixture forming cubic diamond crystals.

Findings

Identified azeotropic points in patchy particle systems for self-assembly.

Mapped phase diagram of a binary mixture assembling into cubic diamond.

Showed azeotropy can simplify multi-component self-assembly pathways.

Abstract

The goal of inverse self-assembly is to design inter-particle interactions capable of assembling the units into a desired target structure. The effective assembly of complex structures often requires the use of multiple components, each new component increasing the thermodynamic degrees of freedom and hence the complexity of the self-assembly pathway. In this work we explore the possibility to use azeotropy, i.e. a special thermodynamic condition where the system behaves effectively as a one-component system, as a way to control the self-assembly of an arbitrarily number of components. Exploiting the mass-balance equations we show how to select patchy particle systems that exhibit azeotropic points along the desired self-assembly pathway. As an example we map the phase diagram of a binary mixture that, by design, fully assembles into cubic (and only cubic) diamond crystal via an azeotropic point. The ability to explicitly include azeotropic points into artificial designs opens novel pathways to the self-assembly of complex structures.