Phase stability of dispersions of hollow silica nanocubes mediated by non-adsorbing polymers

TL;DR

This study experimentally investigates the phase stability of hollow silica nanocube dispersions with non-adsorbing polymers, confirming theoretical predictions through structure factor measurements and visual observations.

Contribution

It provides the first thorough experimental verification of the phase behaviour of cube-polymer mixtures, aligning with theoretical phase boundary predictions.

Findings

Experimental phase boundaries agree with theoretical predictions

Structure factor measurements reveal depletion effects

Visual observations confirm phase stability trends

Abstract

Although there are theoretical predictions [\textit{Eur.~Phys.~J.~E} \textbf{41} (2018) 110] for the rich phase behaviour of colloidal cubes mixed with non-adsorbing polymers, a thorough verification of this phase behaviour is still underway; experimental studies on mixtures of cubes and non-adsorbing polymers in bulk are scarce. In this paper, mixtures of hollow silica nanocubes and linear polystyrene in \textit{N,-N-}dimethylformamide are used to measure the structure factor of the colloidal cubes as a function of non-adsorbing polymer concentration. Together with visual observations these structure factors enabled us to assess the depletion-mediated phase stability of cube-polymer mixtures. The theoretical and experimental phase boundaries for cube-depletant mixtures are in remarkable agreement, despite the simplifications underlying the theory employed.