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

Although there are theoretical predictions [$\mathit{\text{Eur.}}\mathit{\text{Phys.}}\mathit{\text{J.}}\mathit{\text{E}}$ $\mathbf{\text{41}}$ (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 $\mathit{\text{N,-N-}}$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.