Highly efficient fog harvesting system achieved on slippery micro-grooved cones

Abstract

The directional transport of liquid droplets on asymmetrical one-dimensional surfaces has broad applicability, from fog harvesting and oil/water separation to desalination, sensing, and beyond. The balance between driving and hysteresis forces determines the performance of droplet motion. To improve droplet mobility, a common strategy is to increase driving forces by introducing multiple levels/types of asymmetries along the motion direction, or to decrease resistant forces by constructing a slippery surface. However, there have been few attempts to integrate enhanced driving forces and decreased resistance into one system, mainly because traditional lubricant surface is difficult to maintain stability on physically or chemically asymmetrical surfaces. In this study, we demonstrate a new approach by employing flexible polymer brush-enabled slippery technique on a micro-grooved cone structure. We show that this technique significantly enhances droplet motion performance compared to cones with pure micro-grooves or pure polymer brush modification. This improvement is achieved through the simultaneous increase in the Laplace driving force and the decrease in hysteresis. Our design, with its cooperative surface structure and chemical modification, provides new insights for develo** smart surfaces to drive liquid droplets efficiently.

摘要

液滴在不对称一维表面的定向输送具有广泛应用, 包括雾气收集、油水分离、海水淡化及传感等. 液滴所受的驱动力和阻力共同作用决定液滴的运动性能, 为提高液滴的运动性能, 常见的策略是通过在运动方向引入各种不对称结构以增加驱动力, 或者构建光滑表面以减少阻力. 然而, 到目前为止将增**驱动力和降低阻力同时整合到一个体系中的策略仍未见报道, 这主要是由于传统的液体填充润滑表面所需的润滑油很难在物理或化学不对称的表面上稳定存在. 本研究中, 我们提出在具有微沟槽结构的锥表面接枝柔性聚合物分子刷, 即通过协同表面结构和化学修饰来增大液滴在锥结构表面拉普拉斯驱动力并减小粘滞阻力. 结果表明, 与仅具有微沟槽结构的锥和仅具有聚合物分子刷的光滑锥相比, 润滑微沟槽锥可显著提高液滴的运动性能, 本研究为开发高效液滴运输智能表面提供了新思路.