Hasegawa Katsuyuki, Inasawa Susumu
Shiseido Global Innovation Center, 1-2-11 Takashima, Nishi-ku, Yokohama, Kanagawa 220-0011, Japan and Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Tokyo, Japan.
Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Tokyo, Japan.
Soft Matter. 2020 Sep 30;16(37):8692-8701. doi: 10.1039/d0sm01116a.
Drying of volatile oil droplets immersed in a continuous water phase was observed and analysed. Drying sample solutions were sandwiched between two glass plates and the water and oil phases were observed by confocal microscopy. In the initial stage of drying, evaporation of water was dominant and drying of the oil droplets was negligible. However, the rate of water evaporation decreased when the oil droplets were compressed. Comparison of experimental data with a diffusion model of water vapour showed that the decline in drying rates occurred earlier in the experiment than in the theoretical prediction. This implies that compression and narrowing of water paths caused the decline in the rate of water evaporation. After most water had evaporated, evaporation of the oil droplets occurred. The oil droplets did not shrink isotropically and the air-liquid interface invaded into the drying oil droplets. Cross-sectional observation by z-scanning revealed direct exposure of the oil droplets and they were pinned by the residual water phase. The water network between the oil droplets collapsed after the oil droplets had evaporated. The correlation between changes in structures and drying kinetics in both liquid phases was discussed.
对浸没在连续水相中的挥发油滴的干燥过程进行了观察和分析。将干燥的样品溶液夹在两块玻璃板之间，通过共聚焦显微镜观察水相和油相。在干燥初期，水的蒸发占主导，油滴的干燥可忽略不计。然而，当油滴被压缩时，水的蒸发速率下降。将实验数据与水蒸气扩散模型进行比较表明，干燥速率的下降在实验中比理论预测出现得更早。这意味着水路径的压缩和变窄导致了水蒸发速率的下降。在大部分水蒸发后，油滴开始蒸发。油滴并非各向同性收缩，气液界面侵入正在干燥的油滴中。通过z扫描进行的横截面观察显示油滴直接暴露，并且它们被残留水相固定。油滴蒸发后，油滴之间的水网络坍塌。讨论了两个液相中结构变化与干燥动力学之间的相关性。
