Elimination of the Coffee-Ring Effect by Promoting
Particle Adsorption and Long-Range Interaction
- Publication date
- Publisher
Abstract
A Monte
Carlo model has been developed to investigate the transition
from the coffee-ring deposition to the uniform coverage in drying
pinned sessile colloidal droplets.
The model applies the diffusion-limited aggregation (DLA) approach
coupled with the biased random walk (BRW) to simulate the particle
migration and agglomeration during the droplet drying process. It
is shown that the simultaneous presence of the particle adsorption,
long-range attraction, and circulatory motion processes is important
for the transition from the coffee-ring effect to the uniform deposition
of finally dried particles. The absence of one of the specified factors
favors the coffee-ring deposition near the droplet boundary. The strong
outward capillary flow on the latest evaporation stage can easily
destroy the entire particle pre-ordering at the early drying stages.
The formation of a robust particle structure is required to resist
the outward flow and alter the coffee-ring effect