Mechanism of the 2D Crystallization of Latex Particles in Wetting Films
The ordering starts when the thickness of the water layer containing particles becomes approximately equal to the particle diameter. We proved that neither the electrostatic repulsion nor the van der Waals attraction between the particles is responsible for the formation of two-dimensional crystals. The direct observations revealed the main factors governing the ordering – the convective transport of particles toward the ordered region due to water evaporation and only at the nucleus formation stage the attractive capillary forces.
Microphotograph of the "live" process of 2D array formation. The worm-like traces on the top left side of the photograph are the actual trajectories of the particles moving during the exposure period. Particle diameter = 1.7  mm.
© O. D. Velev 1998