Ultraclean Marangoni Drying
Ultraclean drying of a hydrophilic surface can be obtained at room temperature by dissolving vapour of a water-soluble organic liquid (e.g., isopropanol, diacetone alcohol, or 1-methoxy-2-propanol) from air into the water meniscus against the partially immersed hydrophilic surface while it is slowly withdrawn from water into air. The physical origin of this drying phenomenon can be understood by considering the changes in the water/air surface tension that accompany vapour dissolution. Vapour dissolution not only lowers the surface tension but, because of the upward meniscus curvature, creates an additional surface tension gradient along the meniscus profile. This gradient induces a spontaneous flow of water (the so-called Marangoni flow) from the top of the meniscus towards the bulk of the water. Consequently, vapour dissolution causes the meniscus to partially withdraw itself from the hydrophilic surface and assume an apparent non-zero contact angle. It is this physical response that enables a hydrophilic substrate to be withdrawn from water with a dry surface.
KeywordsContact Angle Organic Vapour Surface Tension Gradient Marangoni Effect Safety Data Sheet
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