Asymptotic analysis of liquid films dip-coated onto chemically micropatterned surfaces

The dip coating of chemically heterogeneous surfaces is a useful technique for attaining selective material deposition. For the case of vertical, wetting stripes surrounded by nonwetting regions, experiments have demonstrated that the thickness of the entrained film on the stripes is significantly different than on homogeneous surfaces because of the lateral confinement of the liquid. In the present work, the asymptotic matching of equations based on lubrication theory is used to determine the film thickness, and necessary restrictions on the capillary and Bond numbers are provided. The predictions are in excellent agreement with the existing experimental data, and the classical Landau-Levich formula for homogeneous surfaces is recovered from the analysis in the limit of very wide stripes. (C) 2005 American Institute of Physics.