title: Controlling the drying and film formation processes of polymer solution droplets with addition of small amount of surfactants.
abstract: We studied how the addition of surfactants alters the drying and film formation processes of polymer solution droplets with contact lines strongly fixed by bank structures. We found that even if the amount of surfactant is quite small, it drastically changes the final profile of the polymer film from a ringlike profile to a flat profile. This property is observed commonly, irrespective of the polymer concentration, droplet volume, and type of solvent. We conjecture that the inhomogeneous distribution of the surfactant caused by the outward capillary flow induces the Marangoni flow directed toward the center of the droplet, which suppresses the outward flow. The present phenomenon implies an effective method for controlling the profile of the polymer film in inkjet printing technologies.
authors.affiliation: Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kajiya
authors.forename: Wataru
authors.initials: W
authors.lastname: Kobayashi
authors.forename: Tohru
authors.initials: T
authors.lastname: Okuzono
authors.forename: Masao
authors.initials: M
authors.lastname: Doi
mesh_terms: D011108:Polymers / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D011108:Polymers; D012997:Solvents; D013501:Surface-Active Agents