Uchimura Misaki, Yanagishita Takashi
Department of Applied Chemistry, Tokyo Metropolitan University, 1-1 Minamiosawa, Hachioji, Tokyo 192-0397, Japan.
Langmuir. 2025 Jul 1;41(25):16391-16401. doi: 10.1021/acs.langmuir.5c01679. Epub 2025 Jun 9.
Polymer nanopillar arrays with continuously varying diameters were fabricated by nanoimprinting using anodic porous alumina molds. The obtained polymer nanopillar array exhibited wettability gradient properties, and when a water droplet formed on its surface, it moved spontaneously. A wettability gradient surface was fabricated using a nanopillar array structure, and its inverted structure, nanohole array, and the spontaneous transport distance of water droplets were compared. The spontaneous transport distance of water droplets on the nanopillar array surface was longer than that on the nanohole array surface. To confirm this, the relationships between surface porosity and contact angle were determined in both structures. Although no significant difference in statistical contact angle was found between the two structures, a significant difference was observed in their dynamic contact angles. The contact angle hysteresis of the nanopillar array structure was smaller than that of the nanohole array, and the adhesive force of the water droplets was smaller. This indicates that surfaces with the small contact angle hysteresis and low surface adhesion of water droplets effectively increase the distance over which water droplets move spontaneously, owing to the wettability gradient structure. In addition, a polymer nanopillar array with a partially gradient structure could be formed by nanoimprinting using anodic porous alumina molds. On surfaces with a patterned wettability gradient structure, moving water droplets in any direction is possible. The polymer nanopillar arrays obtained by this process can be used in various applications such as microfluidic devices, water harvesting, and heat transfer enhancement.
通过使用阳极多孔氧化铝模具进行纳米压印，制备了直径连续变化的聚合物纳米柱阵列。所获得的聚合物纳米柱阵列表现出润湿性梯度特性，当水滴在其表面形成时，会自发移动。利用纳米柱阵列结构制备了润湿性梯度表面，并比较了其倒置结构、纳米孔阵列以及水滴的自发传输距离。水滴在纳米柱阵列表面的自发传输距离比在纳米孔阵列表面的更长。为了证实这一点，测定了两种结构中表面孔隙率与接触角之间的关系。尽管两种结构在统计接触角上没有发现显著差异，但在它们的动态接触角上观察到了显著差异。纳米柱阵列结构的接触角滞后小于纳米孔阵列，并且水滴的粘附力更小。这表明具有小接触角滞后和低水滴表面粘附力的表面由于润湿性梯度结构有效地增加了水滴自发移动的距离。此外，通过使用阳极多孔氧化铝模具进行纳米压印，可以形成具有部分梯度结构的聚合物纳米柱阵列。在具有图案化润湿性梯度结构的表面上，水滴可以向任何方向移动。通过该工艺获得的聚合物纳米柱阵列可用于各种应用，如微流体装置、集水和强化传热。
