How to exploit the full potential of the dip-coating process to better control film formation

TLDR

Dip‑coating is a low‑cost, waste‑free, scalable technique that offers precise thickness control and has gained popularity in research and industry, yet its full potential remains underexplored. This article demonstrates how extending processing parameters beyond conventional limits enables the fabrication of increasingly complex and finely controlled nanostructured layers. By precisely tuning withdrawal speed and atmosphere to harness evaporation‑induced self‑assembly, introducing capillary‑induced convective coating for aqueous or dilute solutions, and exploiting these regimes to impregnate porosity, create nanocomposites, or perform nanocasting, the authors show how dip‑coating can produce nanostructured layers ranging from a few nanometers to one micrometer from the same solution.

Abstract

Dip-coating is an ideal method to prepare thin layers from chemical solutions since it is a low-cost and waste-free process that is easy to scale up and offers a good control on thickness. For such reasons, it is becoming more and more popular not only in research and development laboratories, but also in industrial production, as testified by the increasing number of annual publications (9, 180, and 480 articles in 1990, 2000, and 2010, respectively). Even so, the full potential of dip-coating has not yet been fully explored and exploited. This article highlights the recent progresses made by tuning the processing conditions beyond conventional ranges to prepare more and more complex and controlled nanostructured layers. Especially, we will see how one can take advantage of an accurate tuning of the withdrawal speed and of the atmosphere to control the nanostructuration originating from evaporation-induced-self-assembly (EISA), together with the final thickness from a few nm up to 1 μm from the same initial solution. A new regime of deposition, involving capillary induced convective coating that is highly suitable for the deposition from aqueous and/or highly diluted solutions, will be described. Finally, it will be demonstrated that dip-coating is also a well suited method to impregnate porosity, to make nanocomposites, or to perform nanocasting. The present discussion is illustrated with systems of interests in domains such as optics, energies, nanoelectronics, nanofluidics, etc.