The vertical deposition technique [A.S. Dimitrov et al. Langmuir 12 (1996) 1303] [P. Jiang et al. Chem. Mater. 11 (1999) 2132] is based on the deposition of colloidal particles through capillarity when a contact line is moved along the substrate. We used the variant which consists in letting evaporate the continuous phase of the colloidal dispersion. We focus on the effect of concentration in the structure obtained and the speeds of formation of such structures.

We worked with polystyrene spheres of 1.3 μm diameter suspended in water. We use mainly three different concentration, 0.1%, 0.3% and 0.5%. These choice of concentration allowed us to appreciate a full range of deposits from submonolayer structures to multilayer. We measured the speeds from the time evolution of the contact-line contact line position obtained through a CMOS camera.

We obtained (among other interesting things [M. Giuliani et al. Phys. Rev. E 79 (2009) 032401]) that for some concentrations there appear two characteristic speeds that are related to the kind of morphology which is deposited. Also, we proved (in our experimental conditions) that high speeds correspond to multilayer and low speeds to monolayers. This last result is controversial, as some models predicted just the inverse. Those models were based on constant wetting film thickness which is clearly not true in our system (very diluted). The experimental results could be understood based on the existence of a particle pool zone (PPZ) [R. Shimmin et al. Langmuir 22 (2006) 6507] where the local concentration of particles differs from that of the bulk and on the porosity of the previously deposited structures.

• • M. Giuliani et al. Phys. Rev. E 79 (2009) 032401.

  • M. Giuliani, Ph.D. thesis. Universidad de Navarra (2010)

We acknowledge discussions with A. Yethiraj, R. Narhe, R. Sirera, C. Arcos and with the Magneto group of the University of Navarra. This work was partly supported by the Departamento de Educación (Gobierno de Navarra) and by the Spanish MEC (refs. MAT2003-02369, FIS2007-66004-C02-01 and FIS2008-01126). M. Giuliani acknowledges partial financial support from the "Asociación de Amigos de la Universidad de Navarra". We also acknowledge technical support of Y. Olaizola's group

Four kind of morphologies (NC, non compact; NCD, non compact dense; CM, compact monolayer; ML, multilayer) that appear for diluted concentrations (scale bar 10 μm):

Sketch for vertical deposition (lateral view). Arrows in the fluid are hydrodynamical flows, and in the open atmosphere denote evaporation.

Sketch for formation of vertical stripes. LSMF stands for Large Scale Mean Flow (of convective type). Arrows in the fluid are (other) hydrodynamical flows.