仿生集水纤维研究进展及应用

Research Progress and Application of Biomimetic Fiber Water Harvesting

淡水资源短缺是全球共同面临的严峻挑战。相关研究发现,模仿蜘蛛丝等生物结构从空气中收集水分,是缓解当前水资源危机的有效途径,已成为仿生集水领域的研究焦点。本文从基础润湿理论、液滴定向传输机理、定向集水机制、仿生纤维设计特点及制备方法等方面进行了综述,重点介绍了Young’s方程、Wenzel模型以及Cassie-Baxter模型等基础润湿理论。将纤维集水过程划分为冷凝结露、定向运输和液滴脱附3个阶段,并深入阐述了蜘蛛丝集水过程的内在机制,包括拉普拉斯压力梯度、表面能梯度、滞后效应和液滴悬挂能力。分析了影响集水效率的关键因素,并列举了提升纤维集水效率的常用策略。归纳了仿生纤维结构的主要仿生对象、仿生原理以及所采用的主要制备技术,并对不同技术的优缺点及适用场景进行了详细分析。最后,对不同仿生纤维网状集水器的集水特点和集水效率进行了比较,分析了仿生纤维集水技术在大气水收集、海水淡化、工业蒸气回收以及油水分离等领域的应用潜力,并对该技术的未来发展方向及现有不足提出了改进意见和展望。

Water is the source of life and an indispensable natural resource in the process of human production,life and social development.However,water shortage is a serious challenge faced by all countries in the world.Solving the problem of water scarcity is a serious challenge faced by the global community.Previous studies have shown that mimicking natural structures like spider silk to extract water from the air is a feasible way to alleviate the water crisis.This method has advantages such as low cost,easy accessibility,and energy efficiency,making it a hot topic in the field of biomimetic water harvesting.Therefore,it is necessary to summarize the research progress of biomimetic fiber water harvesting.The work aims to provide a comprehensive review on the basic wetting theory,the mechanism of liquid droplet directional transport and water harvesting,as well as the design features and preparation of biomimetic fibers.The basic wetting theory models are introduced,including Young's equation,Wenzel model,and Cassie-Baxter model.At the same time,the harvesting of water droplets on fibers is divided into three stages of cold condensation,directional transport,and droplet removal.The main principles of fiber water harvesting are expounded,including difference in Laplace pressure,surface energy gradient,hysteresis effects,and hanging ability,as well as the key factors affecting water harvesting efficiency.Common strategies for the three stages of optimization are also listed.Combining the non-uniform wettability design with the biological special structure can promote the droplet cold condensation.The microstructures promoting droplet directional transport include spider silk spindle knot,cactus spine structure,and Sarracenia groove structure.The design of hollow spindle knot and a bioinspired helical-groove-modified spindle-knot can improve the hanging ability of fiber.The low hysteresis of hydrophobic and smooth surfaces is used to accelerate droplet removal.At the same time,efficient desorption can also be achieved through self-induced droplet jump,droplet sweep and droplet collision during droplet dropping.Ideas are provided for the design of efficient water-harvesting fibers and how to balance the constraints between droplet condensation and droplet removal.Furthermore,the main biomimetic objects,biomimetic principles,and the primary preparation techniques of biomimetic fiber structures are discussed.The bionic fiber is mainly inspired by the spindle knot structure of spider silk.Many biomimetic knotting fibers use different methods to make various types of knots,including commonly used methods such as dip coating,fluid coating,electrospinning microfluidic control,as well as more precise emerging methods like dynamic interface spinning and 3D printing.The advantages and disadvantages of different preparation techniques and their applicable scenarios are analyzed.Additionally,the water harvesting characteristics and efficiency of biomimetic fiber mesh water harvesters are compared.Finally,the application prospects of biomimetic fiber water harvesting technology in atmospheric water harvesting,seawater desalination,industrial steam recovery,and oil-water separation are summarized,and the future development and existing shortcomings of biomimetic fiber water harvesting technology are put forward.This will help to comprehensively understand the mechanism and behavior of fiber water harvesting,and promote the development of water harvesting efficiency,harvester design,fluid control,and functional materials in various fields.