Graduate School of Medicine, Science & Technology, Shinshu University, 3-15-1 Ueda, Nagano, 386-8567, Japan.
Sci Rep. 2020 Feb 10;10(1):2250. doi: 10.1038/s41598-020-59149-2.
Re-entrant texturing may potentially improve the hydrophobicity and oleophobicity of a surface. The food industry requires a microfabrication method to keep surfaces clean without leaving a packaging residue for applications such as food bottles, food containers, and preservation bags. The goal of this study is thus to establish a microfabrication method for re-entrant texturing with spherical curvature to produce hydrophobic/oleophobic surfaces for liquid foods, such as soy sauce and canola oil. Samples with a spherical curvature are created from an ultra-violet-cure (UV-cure) resin and poly (tetrafluoroethylene) (PTFE) microbeads with diameters between 2.26 to 1,353 microns by spin coating on a glass substrate. The resin thickness, the mass and diameter of the microbeads, and the spin coater rotation speed are used as the microfabrication parameters. A side view of samples showing the spherical curvature reveals that a re-entrant texture indeed forms. Distilled water, soy sauce, and canola oil are dropped softly onto the re-entrant surface, however, the droplets cannot be placed stably. For appropriate microbead diameters, the apparent contact angles of soy sauce and canola oil showed 130.2 and 119.4 degrees, respectively. This facile fabrication method for re-entrant surfaces could prove useful for generating hydrophobic/oleophobic surfaces for Newtonian liquid foods.
再入式纹理处理有可能提高表面的疏水性和疏油性。食品工业需要一种微制造方法来保持表面清洁，而不会在食品瓶、食品容器和保鲜袋等应用中留下包装残留物。因此，本研究的目的是建立一种具有球形曲率的再入式微结构制造方法，以生产用于液体食品（如酱油和菜籽油）的疏油/疏水性表面。通过在玻璃基板上旋涂具有 2.26 至 1353 微米直径的紫外线（UV）固化树脂和聚四氟乙烯（PTFE）微珠，制造出具有球形曲率的样品。树脂厚度、微珠的质量和直径以及旋涂器的旋转速度被用作微制造参数。从侧视图可以看出，样品确实形成了再入式纹理。将蒸馏水、酱油和菜籽油轻轻滴在再入式表面上，但液滴不能稳定放置。对于合适的微珠直径，酱油和菜籽油的表观接触角分别为 130.2 和 119.4 度。这种用于制造再入式表面的简单制造方法可能有助于为牛顿液体食品生成疏油/疏水性表面。
