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Isaac Newton Institute for Mathematical Sciences

A theoretical description of pattern formation in dip-coating processes

Presenter: Walter Tewes (Institute for Theoretical Physics, University of Münster)

Co-author: Svetlana V. Gurevich (Institute for Theoretical Physics, University of Münster)

Abstract

Dip-coating is a method widely used to prepare patterns with thickness control on substrates. Using a solution of an organic semiconductor, the growth of dendritic structures of monolayer and multilayer thickness can be achieved [1]. The thickness as well as the morphology of the deposited layer can be controlled by adjusting the transfer velocity. In this work, we investigate theoretically the formation of dendritic structures by means of a dynamical continuum model. We use thin film equations for solutions derived by a long wave expansion. This approach yields a system of coupled PDEs for the temporal evolution of solution layer thickness and solute concentration. In addition, the conservative part of such equations can be written in a gradient formulation [2], allowing a self-consistent inclusion of further contributions to the free energy of the system in question.

[1] Li, Liqiang, et al. "Structure Formation by Dynamic Self‐Assembly." Small 8.4 (2012): 488-503. [2] Thiele, U. "Note on thin film equations for solutions and suspensions." The European Physical Journal Special Topics 197.1 (2011): 213-220.