一维锥表面润滑油膜的稳定构建及其对液滴运动性能的调控

One-dimensional conical structure is an ideal fog harvesting model system. The mobility of micro-sized water droplets on the conical surfaces is crucial to the overall fog harvesting efficiency. However, the current one-dimensional conical surfaces show large resistant hyeteresis and thus low mobility of water droplets, as well as low rebirth rate of the fog harvesting surfaces, which is the bottle neck for further enhancement of the fog harvesting efficiency. To solve this problem, a reliable method is to introduce a lubricant oil film on the one-dimensional conical surface, changing the contacting mode between water droplets and the substrates and improving the droplets’ mobility. In this project, we plan to stabilize the lubricant film on the rough surface via grafting a layer of polymer brush. The lubricant film will lead to reduced hysteresis upon the droplet, enhance the droplet’s mobility and refresh rate of the fog harvesting surfaces, and finally an efficient fog harvesting surface model. The emphasis will be to study and unveil the influence of polymer brushes’ chemical composition, the chain length, and the grafting density on the stability of the lubricant oil film. Study in-depth mechanism of the lubricant oil film’s stability under shear force from a moving droplet, from perspectives of the oil’s viscosity and surface tension. After realizing the stable lubricant film on the one-dimensional conical surface, we will further study the impact of the oil’s rheological and wettability properties on the water droplets’ mobility and get the optimizd parameters for enhancing fog collention efficiency. The implementation of this project will supply theoretical and experimental fundations for developing efficient fog collection surfaces.

一维锥结构是理想的雾水收集表面模型体系。液滴在锥表面的运动性能是影响集雾效率的关键。然而，现有一维锥表面对液滴粘滞力大，导致液滴运动性能和集雾表面重生速率低，是限制雾水收集效率进一步提升的瓶颈。在一维锥表面引入稳定的润滑油膜，改变液滴与表面的接触状态并改善其运动性能是解决上述问题的有效手段。本项目拟通过粗糙表面接枝聚合物分子刷方法在一维锥表面构建稳定的润滑油膜，减小液滴在接触表面的粘滞力，提升液滴运动性能和集雾表面重生速率，构建高效雾水收集表面模型。着重研究并阐明分子刷化学组成、接枝长度、及接枝密度对油膜稳定性的影响规律，深入理解润滑油粘度和表面张力对油膜抗运动液滴剪切剥离的作用机制，实现一维锥表面稳定油膜的构建。在此基础上，研究并揭示润滑油的流变性质和浸润性质对液滴所受粘滞力的调控机制，提高其运动性能，提升雾水收集效率。本项目的实施将为发展高效雾水收集表面提供理论依据和实验基础。

雾水收集是缓解局部地区淡水资源短缺的重要途径。液滴在集雾表面的运动性能影响最终集雾效率。针对现有集雾表面液滴运动粘滞力大，运动速度低导致雾水收集效率低的问题，本项目在一维锥结构表面构筑了聚合物分子刷稳定的润滑油膜。研究了接枝反应条件、接枝聚合物种类对润滑油膜稳定性的作用规律。通过与传统毛细作用稳定的润滑表面进行比较，揭示了聚合物分子刷稳定润滑油膜的机理在于二者间强的范德华作用力，且这一作用力的根源是一端固定的聚合物分子刷与游离的润滑油具有相同的化学组成单元。调控润滑油的粘度和表面张力，研究小液滴在覆盖有稳定润滑油膜的锥形铜丝表面的运动性能。将稳定有润滑油膜的锥形铜丝与吸水性基底相结合，构筑了雾水收集系统，探索了润滑油膜性质对雾水收集效率的影响。本项目为发展高效连续雾水收集器提供了实验依据和理论基础。