Understanding interfacial gas retention under water: A materials approach using aligned carbon nanotube architectures

植物和动物经过数百万年的进化，形成了高度复杂的分层结构表面，以适应特定的环境条件。一些昆虫、蜘蛛和植物甚至能够在水下保持持久的气体层。这些空气层和不同的支撑结构是本研究项目中采用的仿生全碳基材料系统的“活榜样”。该项目的重点是超疏水气体保持垂直排列碳纳米管（VACNTs）。该合作研究项目旨在探索允许气体在水和其他溶剂下保持的物理和化学材料基础。碳纳米管，尤其是vacnt，已被认为是具有广泛可调的化学和物理性质的有价值的材料，包括它们的排列和化学表面功能化。这种材料的惊人可变性可以在长度，直径，弹性，化学功能上进行定制，提供各种重要特性（例如机械强度，pH值，腐蚀和污垢电阻率），这将使对水下气体保留的基础进行广泛的研究成为可能。它是独特的，可以作为一个模型结构，以深入了解界面材料的性质，如物理表面结构和化学表面功能，这都是获得这种行为所必需的。在气体保留材料领域，对材料发展的更深入和完整的理解可能会产生什么一般影响？了解所提出的VACNT模型系统中气体和空气保留的基本原理将为水下空气保留表面的未来利用奠定基础，水下空气保留表面在各种工程和科学领域的应用，从减阻或气体交换到传感系统。尽管减阻已经成为工程师和生物学家关注的焦点，但压力传感和气体交换等领域迄今为止的研究和理解还很有限。这可以归因于缺乏直接可获得的材料或复杂的技术来获得这些材料或两者的结合。使用vacnt作为模型材料可以克服这个问题，并且根据气-水界面定制几何（物理）和表面（化学）特性将使我们能够揭示控制其气体保持特性的因素。为了实现这些目标，本提案将解决的具体任务是：通过调整vacnt的几何参数（直径、距离、高度、倾角）和表面化学（通过表面功能化调整疏水性）来调整其物理和化学表面性质。确定水气界面的形状和尺寸稳定性，对不同压力条件下的稳定性，气体环境的改变，气体交换和溶剂环境。

Plants and animals have evolved over millions of years highly complex hierarchical structured surfaces as an adaptation to particular environmental conditions. Some insects, spiders and plants are even able to maintain persistent gas layers under water. These air layers and the different supporting structures serve as “living role models” for the biomimetic all carbon based material system employed in this research project. The project focusses on super hydrophobic gas retaining vertically aligned carbon nanotubes (VACNTs). The collaborative research project aims to explore the physical and chemical material fundamentals allowing gas retention under water and other solvents. CNTs and especially VACNTs have been established as valuable materials with widely tunable chemical and physical properties including their alignment and chemical surface functionalization. The amazing variability of this material which can be tailored in length, diameter, elasticity, chemical functionality, providing a variety of important properties (e.g. mechanical strength, pH and corrosion and fouling resistivity) will enable extensive studies on the basics of gas retention under water. It is unique and can serve as a model structure to gain deeper insight into the interfacial material properties like physical surface structure and chemical surface functionality which are both necessary to obtain such a behavior. What general impact might a deeper and complete understanding on materials development in the area of gas retention materials have? Understanding the fundamentals of gas and air retention in the proposed VACNT model system will lay the foundation for the future utilization of under water air retaining surfaces which have applications in various fields of engineering and science going from drag reduction or gas exchange to sensory systems. Whereas drag reduction has already been in the focus of engineers and biologists areas like pressure sensing and gas exchange are so far only sparsely studied and understood. This can be attributed to a lack of either straightforward accessible materials or elaborate techniques to obtain those or a combination of both reasons. With the usage of VACNTs as model material this could be overcome and tailoring the geometric (physical) and surface (chemical) properties with respect to the gas-water interface will enable us to unravel the factors which govern their gas retention properties. Specific tasks in this proposal which will be addressed to reach these goals are: Tuning of the physical and chemical surface properties of VACNTs by adjusting their geometrical parameters (diameter, distance, height, inclinement) and their surface chemistry (tuning hydrophobicity by surface functionalization). Determining the shape and stability of the water-gas interface with respect to size, stability towards different pressure conditions modification of the gas environment, exchange of gases and solvent environment.