Hindered cracking in colloidal suspension coatings via evaporation‐driven lyotropic liquid crystals

Abstract We demonstrate that lyotropic liquid crystalline (LC) phases, formed by the molecular interactions between 1‐glyceryl monooleyl ether (GME) and water, offer new pathways for producing crack‐free particulate films from colloidal suspensions. Drying experiments on titanium dioxide‐ethanol‐water‐GME suspension systems revealed a 15‐fold increase in the critical cracking thickness, above which cracks spontaneously evolve, compared to suspensions without additives. Contrary to previous theoretical predictions based on capillary forces, the critical thicknesses ethanol‐lean suspensions increased with higher particle packing volume fractions in the dried films. We developed a new phenomenological model that incorporates the formation of viscoelastic LC phases and found it to be in quantitative agreement with measurements. This suggests a versatile route for delaying cracking by introducing thermodynamically metastable phases of amphiphilic molecules. The evaporation‐induced isotropic‐LC transition was further verified by numerical predictions of the compositional trajectories on the phase diagram.