Evaporative deposition patterns: spatial dimensions of the deposit

Area of Science:

• Colloid science
• Materials science
• Fluid dynamics

Background:

• Evaporating sessile drops of colloidal solutions form characteristic deposit patterns.
• Previous models often neglect the finite volume of solute particles, limiting predictive accuracy.

Purpose of the Study:

• To develop a theoretical model for colloidal deposition patterns that accounts for the finite spatial dimensions of solute particles.
• To establish the relationship between geometrical characteristics of deposition patterns and key experimental parameters.

Main Methods:

• A theoretical model based on steric effects of solute particles was developed.
• The model was solved analytically for low concentrations and numerically for arbitrary concentrations.
• Theoretical predictions were compared with experimental data.

Main Results:

• Geometrical characteristics of deposition patterns are functions of initial concentration, drop geometry, and drying time.
• The finite size of solute particles is shown to be the cause of observed dependencies on experimental parameters.
• The model demonstrates good agreement with experimental results.

Conclusions:

• The proposed model accurately predicts colloidal deposition patterns by incorporating solute particle dimensions.
• These findings provide a universal, parameter-free explanation for evaporative deposition phenomena.
• The results are valuable for understanding and controlling material deposition processes.