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Wetting, superhydrophobicity, and icephobicity in biomimetic composite materials.

机译：仿生复合材料的润湿性，超疏水性和憎冰性。

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摘要

Recent developments in nano- and bio-technology require new materials. Among these new classes of materials which have emerged in the recent years are biomimetic materials, which mimic structure and properties of materials found in living nature. There are a large number of biological objects including bacteria, animals and plants with properties of interest for engineers. Among these properties is the ability of the lotus leaf and other natural materials to repel water, which has inspired researchers to prepare similar surfaces. The Lotus effect involving roughness-induced superhydrophobicity is a way to design nonwetting, self-cleaning, omniphobic, icephobic, and antifouling surfaces. The range of actual and potential applications of superhydrophobic surfaces is diverse including optical, building and architecture, textiles, solar panels, lab-on-a-chip, microfluidic devices, and applications requiring antifouling from biological and organic contaminants.;In this thesis, in chapter one, we introduce the general concepts and definitions regarding the wetting properties of the surfaces. In chapter two, we develop novel models and conduct experiments on wetting of composite materials. To design sustainable superhydrophobic metal matrix composite (MMC) surfaces, we suggest using hydrophobic reinforcement in the bulk of the material, rather than only at its surface. We experimentally study the wetting properties of graphite-reinforced Al- and Cu-based composites and conclude that the Cu-based MMCs have the potential to be used in the future for the applications where the wear-resistant superhydrophobicity is required.;In chapter three, we introduce hydrophobic coating at the surface of concrete materials making them waterproof to prevent material failure, because concretes and ceramics cannot stop water from seeping through them and forming cracks. We create water-repellant concretes with CA close to 160o using superhydrophobic coating.;In chapter four, experimental data are collected in terms of oleophobicity especially when underwater applications are of interest. We develop models for four-phase rough interface of underwater oleophobicity and develop a novel approach to predict the CA of organic liquid on the rough surfaces immersed in water. We investigate wetting transition on a patterned surface in underwater systems, using a phase field model. We demonstrated that roughening on an immersed solid surface can drive the transition from Wenzel to Cassie-Baxter state. This discovery improves our understanding of underwater systems and their surface interactions during the wetting phenomenon and can be applied for the development of underwater oil-repellent materials which are of interest for various applications in the water industry, and marine devices.;In chapter five, we experimentally and theoretically investigate the icephobicity of composite materials. A novel comprehensive definition of icephobicity, broad enough to cover a variety of situations including low adhesion strength, delayed ice crystallization, and bouncing is determined. Wetting behavior and ice adhesion properties of various samples are theoretically and experimentally compared. We conclude superhydrophobic surfaces are not necessarily icephobic. The models are tested against the experimental data to verify the good agreement between them. The models can be used for the design of novel superhydrophobic, oleophobic, omniphobic and icephobic composite materials.;Finally we conclude that creating surface micro/nanostructures using mechanical abrasion or chemical etching as well as applying low energy materials are the most simple, inexpensive, and durable techniques to create superhydrophobic, oleophobic, and icephobic materials.
机译：纳米技术和生物技术的最新发展需要新材料。近年来出现的这些新类别的材料中，仿生材料模仿了在自然界中发现的材料的结构和特性。有许多生物学对象，包括细菌，动植物，它们具有工程师感兴趣的特性。在这些特性中，荷叶和其他天然材料具有排斥水的能力，这启发了研究人员准备类似的表面。涉及粗糙度引起的超疏水性的​​莲花效应是一种设计不润湿，自清洁，疏油，疏冰和防污表面的方法。超疏水表面的实际和潜在应用范围是多种多样的，包括光学，建筑和建筑，纺织品，太阳能电池板，芯片实验室，微流体设备以及需要生物和有机污染物防污的应用。在第一章中，我们介绍了有关表面润湿特性的一般概念和定义。在第二章中，我们开发了新颖的模型并进行了复合材料润湿的实验。为了设计可持续的超疏水金属基复合材料（MMC）表面，我们建议在材料的大部分中而不是仅在其表面使用疏水增强。我们通过实验研究了石墨增强的铝和铜基复合材料的润湿性能，并得出结论，铜基MMC可能在将来用于要求耐磨超疏水性的​​应用中。 ，我们在混凝土材料的表面引入疏水涂层，使它们防水以防止材料损坏，因为混凝土和陶瓷无法阻止水渗入它们并形成裂缝。我们使用超疏水性涂料制造了CA接近160o的憎水混凝土。第四章，从疏油性方面收集了实验数据，尤其是在水下应用时。我们开发了水下疏油性的四相粗糙界面模型，并开发了一种新颖的方法来预测浸入水中的粗糙表面上的有机液体的CA。我们使用相场模型研究水下系统中图案化表面上的润湿转变。我们证明了在浸没的固体表面上进行粗糙化可以驱动从Wenzel到Cassie-Baxter状态的转变。这一发现增进了我们对润湿现象期间水下系统及其表面相互作用的理解，可用于开发水下驱油材料，这些材料在水工业和船舶设备的各种应用中都受到关注。我们在实验和理论上研究了复合材料的憎冰性。确定了一种新颖的全面的憎冰性定义，其含义足以涵​​盖各种情况，包括低粘附强度，延迟的冰结晶和弹跳。从理论上和实验上比较了各种样品的润湿行为和冰粘附特性。我们得出结论，超疏水表面不一定是疏冰表面。针对实验数据对模型进行了测试，以验证它们之间的良好一致性。该模型可用于设计新型的超疏水，疏油，全疏和疏冰复合材料。最后，我们得出结论，使用机械磨蚀或化学蚀刻以及应用低能材料来创建表面微/纳米结构是最简单，廉价的方法，耐用的技术来制造超疏水，疏油和憎冰材料。

著录项

  • 作者

    Hejazi, Vahid.;

  • 作者单位

    The University of Wisconsin - Milwaukee.;

  • 授予单位 The University of Wisconsin - Milwaukee.;
  • 学科 Engineering Mechanical.;Engineering Materials Science.;Chemistry Physical.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 201 p.
  • 总页数 201
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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