How Complex Fluids Dry? Flow, Solidification, and Pattern Formation

Evaporation-driven pattern formation occurs across different engineered systems like coatings and printed films. In colloidal suspensions, interactions among fluid flows, including evaporation, capillary and Marangoni flows, generally transport particles toward the contact line during evaporation, resulting in various drying morphologies. While such behavior is dominated by fluid flow in colloidal suspensions, in more complex systems where particles are dispersed within polymer solutions, the combined effects of particle-induced advection and polymer rheology produce intricate drying behaviors that need further investigation to elucidate the coupling between particle transport and polymer rheology.

We investigate the drying of colloidal suspensions under controlled parameters to determine how fluid flow and particle interactions shape the final pattern. The analysis is extended to polymer and particle–polymer mixtures, where increasing polymer concentration transforms the liquid from Newtonian to viscoelastic. In this transition, elastic stresses emerge as the polymer matrix stores and releases energy. The resulting elastic stresses interact with fluid flow, creating complex morphologies. This study explains how particle and liquid properties govern drying behavior, providing a foundation for controlling structure formation in various applications.