Authors: P. Lebedev-Stepanov
Affilation: Photochemistry Center, Russian Federation
Pages: 149 - 152
Keywords: self-assembly, self-ordering, dissipative particle dynamics, Langevin equation, colloidal solution
A method of dissipative particle dynamics of charged colloidal submicro- and nanoparticles in evaporating picoliter droplet of solution deposited on plane substrate is proposed for investigation of self-assembly and self-ordering of colloids during solute evaporation, and design of dry colloidal pattern. Method is based on the numerical solution of multi-scale Langevin equation for each particle, the hydrodynamic microflows approach, and droplet evaporation model. The method takes into account the DLVO-forces between the particles, their interaction with the substrate (adhesion, friction, roughness); Stokes’, Brownian, and capillary forces (wetting and depinning, outflow angles, surface tension). The self-assembled pattern morphology dependence on the model parameters is investigated. The nature of coffee ring effect was studied. It is shown that the hexagonal domain ordering of particles ensemble in pattern can be formed onto plane substrate as a result of interparticle repulsion and the capillary compression during evaporation of solvent. Numerical results are in good agreement with experiments on self-assembly in colloidal droplet deposited by inkjet technology. The application includes inkjet technologies and printable electronics fabrications; medical diagnostics by dry pattern analysis, design of microstructures and materials with new properties.