Easy control of surface morphology through a natural phenomenon

Abstract This paper provides an innovative controlling process of surface morphology. The contact area between a liquid and a solid is strongly affected by the critical surface tension (cft) of both materials. Using this phenomenon, a wide range of morphologies, from flat surface layers to sea‐grape‐like surface structures, were created. Due to the bleed‐out phenomenon, low‐molecular‐mass additive (liquid) oozed out of a precursor polymer (solid), leading to different surface morphologies depending on the cft values of the liquid (Mcft) and solid (Pcft). When Mcft < < Pcft, a flat surface layer was obtained; however, in the case of Pcft < < Mcft, the formation of a sea‐grape‐like surface layer was created. Tetra‐butoxy‐titanium and polydimethylsiloxane were used as low‐molecular‐mass additive and precursor polymer, respectively. After coating on titanium metal and calcination, sea‐grape‐like materials composed of titanium oxide and silicon oxide were obtained. Furthermore, unique characteristics (bioactivity, photocatalytic activity, and prevention of atomic diffusion) were observed. A remarkable increase in the wettability, bioactivity, and catalytic activity of materials was achieved using our simple process to create unique surface morphologies. Our proposed process is applicable to a wide range of materials and morphologies, and can be used in catalysts, biomaterials, and environmental barrier coatings.