Wettability of Solid Surface. VI. The Effects of Metallic Cations on Stearic Acid Built-up Film

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Abstract
1. Wettability of mixed built-up film of stearic acid and barium or calcium stearate decreased with the number of layers, the advancing contact angle tending to the value of about 115°. The difference between θa and θr of built-up film was larger than that of solidified surface. 2. X-film and Y-film of barium or calcium stearate prepared occasionally at almost the same condition showed the same wettability. Increase of barium or calcium content in the film was considered to result in the wettability decrease. 3. Of the three types of metallic ion classified according to the influence on wettability of stearic acid, the following two were studied precisely. (a) Ions of the type III, forming relatively simple stoichiometric compound with stearic acid, the stearates being able to overturn themselves easily in the surface, and the wettability changing with the condition. (Ba, Ca) (b) Ions of the type II, forming a network of a complex structure with stearic acid, which overturn themselves with difficulty in the surface and their wettability does not change with the condition. II—1. Ions, rapidly forming network and render the surface hydrophilic tempolarily. (Al, Cu) II—2. Ions, slowly forming network and rendering the surface hydrophobic (Hg).