Effect of Colloidal Surface Charge on Desiccation Cracks

Wereport the effect of polarity and surface charge density onthe nucleation and growth kinetics of desiccation cracks in depositsof colloids formed by drying. We show that the average spacing betweendesiccation cracks and crack opening are higher for the deposit ofpositively charged colloids than that of negatively charged colloids.The temporal evolution of crack growth is found to be faster for positivelycharged particle deposits. The distinct crack patterns and their kineticsare understood by considering the spatial arrangement of particlesin the deposit, which is strongly influenced by the substrate-particleand particle-particle interactions. Interestingly, the crackspacing, the crack opening, and the rate at which the crack widensare found to increase upon decreasing the surface charge of the colloids.

Automated summary

This study reports on the influence of polarity and surface charge density on the nucleation and growth kinetics of desiccation cracks in colloidal deposits during drying. The results show that deposit formed by positively charged colloids has higher average spacing between cracks and crack opening compared to that formed by negatively charged colloids. The temporal evolution of crack growth is found to be faster for deposits of positively charged particles. The distinct crack patterns and kinetics are explained by considering the spatial arrangement of particles in the deposit, which is strongly influenced by the substrate-particle and particle-particle interactions. Interestingly, decreasing the surface charge of the colloids leads to an increase in crack spacing, crack opening, and crack widening rate.