Preparation of Sol−Gel Films by Dip-Coating in Extreme Conditions

作者：Marco Faustini, Benjamin Louis, Pierre Antoine Albouy, Monika Kuemmel, David Grosso · 发表于：The Journal of Physical Chemistry C · 年份：2010 · DOI：10.1021/jp9114755 · 被引用次数：311 · 研究领域：Fluid Dynamics and Thin Films、Nanomaterials and Printing Technologies、Innovative Microfluidic and Catalytic Techniques Innovation

Dip-coating of sol−gel solutions is a complex dynamic process that is difficult to model because it is associated with time-dependent evaporation-induced concentration and viscosity gradients in the solution. It is, however, highly used in the coating technology because it is simple and provides excellent reproducibility. Existing fair models have been proposed some decades ago to describe this method, but they are based on Newtonian and nonevaporating liquids and require several important assumptions and simplifications. In this work, we present a simple experimental study of sol−gel film formation by dip-coating, through which we propose a general semiexperimental model to predict the final film thickness. Spectroscopic ellipsometry was used as the main technique to obtain the film physical thickness and optical density for various dip-coating processing conditions (withdrawal speeds from 0.01 to 20 mm·s −1 and temperatures from 25 to 60 °C) and for several different chemical solutions (TiCl 4, TEOS, and MTEOS, all in the presence, or not, of block PEO- b -PPO copolymer templates in EtOH/H 2 O, with concentrations from 10 −1 to 10 −3 mol·L −1 ). We show that phenomena that are difficult to assess during deposition, such as viscosity variation, evaporation cooling, chemical reaction, and thermal Marangoni flow, may not have to be taken into account. The influences of various experimental parameters are discussed together with the limitations and the full potentiality of the ...