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Author: Solomon E. Adera Publisher: ISBN: Category : Languages : en Pages : 68
Book Description
A droplet deposited on a rough, lyophilic surface satisfying the imbibition condition, results in spontaneous spreading and hence complete wetting. However, in this thesis, we demonstrate that this wetting behavior can be altered by superheating the substrate such that droplets can reside in a non-wetting state due to evaporation. Photolithography and deep reactive ion etching were used to fabricate well-defined silicon micropillar arrays with a square pattern with varying pillar diameter, height, and center-to-center spacing. Water droplets placed on these microstructured surfaces at room temperature demonstrated superhydrophilic behavior with liquid filling the voids between pillars resulting in very low contact angle, and hence complete wetting. However, when the microstructured surface was superheated above a critical superheat, the superhydrophilicity was lost and non-wetting droplets were formed on the top surface of the micropillar array structure. The superheat required to deposit a non-wetting droplet (> 75°C) was found to be significantly higher than that required to sustain an already deposited non-wetting droplet (
Author: Solomon E. Adera Publisher: ISBN: Category : Languages : en Pages : 68
Book Description
A droplet deposited on a rough, lyophilic surface satisfying the imbibition condition, results in spontaneous spreading and hence complete wetting. However, in this thesis, we demonstrate that this wetting behavior can be altered by superheating the substrate such that droplets can reside in a non-wetting state due to evaporation. Photolithography and deep reactive ion etching were used to fabricate well-defined silicon micropillar arrays with a square pattern with varying pillar diameter, height, and center-to-center spacing. Water droplets placed on these microstructured surfaces at room temperature demonstrated superhydrophilic behavior with liquid filling the voids between pillars resulting in very low contact angle, and hence complete wetting. However, when the microstructured surface was superheated above a critical superheat, the superhydrophilicity was lost and non-wetting droplets were formed on the top surface of the micropillar array structure. The superheat required to deposit a non-wetting droplet (> 75°C) was found to be significantly higher than that required to sustain an already deposited non-wetting droplet (
Author: Vincent Senez Publisher: John Wiley & Sons ISBN: 1119015286 Category : Technology & Engineering Languages : en Pages : 211
Book Description
Texturing surfaces at micro- and/or nano-scales modifies the interactions of liquids and solids. This book is a summary of the state of the art concerning the development and use of micro/nano-technologies for the design of synthetic liquid repellent surfaces with a particular focus on super-omniphobic materials. It proposes a comprehensive understanding of the physical mechanisms involved in the wetting of these surfaces and reviews emerging applications in various fields such as energy harvesting and biology, as well as highlighting the current limitations and challenges which are yet to be overcome.
Author: Hyuk-Min Kwon Publisher: ISBN: Category : Languages : en Pages : 53
Book Description
Considering that contacts between liquid and solid are ubiquitous in almost all energy processes, including steam turbines, oil pumping, condensers and boilers, the efficiency of energy transportation can be maximized such that the liquid-solid interaction is optimized. Texture based super-hydrophobicity, also known as the Lotus effect, has been one of the most extensively studied topics in the last decade. Many of the recent studies have focused on how textures induce more water repellency, and how these textures can be manufactured with different methods and materials. However, few studies have shown how these surfaces benefit the real energy processes in which the interaction between liquid droplets and solid surfaces is vigorous and influences the energy transfer performances. This work focuses on altering the hydrodynamics of droplets with nano-engineered surfaces such that it enables a variety of energy transport processes to achieve better efficiency. Firstly, the wetting transition on textured super-hydrophobic surfaces is explored. The careful investigation of Cassie-Baxter to Wenzel transition of a pendant drop during the deposition explains that the rapid deceleration-induced water hammer pressure causes the transition. This new transition mechanism for large droplets enables a new wetting transition phase diagram with a previously known Laplace mechanism that explains the small drop transition. Another class of non-wetting droplet, the Leidenfrost drop, is studied with textured super-wetting surfaces. The liquid drop loses its contact to the solid by its own vapor, created by a large superheat from the solid. The Leidenfrost effect is undesirable in cooling applications as the vapor layer acts as a barrier for heat transfer. Here, it has been studied that how textured super-hydrophilic surfaces induce droplets to wet at higher superheat via capillary wicking compare to smooth surfaces. A physical model based on scaling is developed to predict the Leidenfrost drop on single length scale textures, and validated by the experiments. Additionally, the physical mechanism suggests that hierarchical textures have a higher Leidenfrost temperature compared to single-length-scale textures, confirmed experimentally. Lastly, the recently discovered rare-earth oxide ceramics are studied, which ensures the benefits of water repellency under harsh conditions such as high temperature and abrasive wear. Texturing of the rare-earth oxide ceramic is explored by the laser ablation technique. Unique micro- and nano-scale hierarchical textures are created, enhancing the water repellency, resulting in the super-hydrophobic rare-earth ceramic.
Author: Annarosa Gugliuzza Publisher: John Wiley & Sons ISBN: 1119028639 Category : Science Languages : en Pages : 333
Book Description
This book addresses the reader to use synergistically the concepts of membranes and sensors materials. It contains insightful contributions from leading scientists working in both the fields. The focus is on the fabrication of smart membranes from sensor materials and related impact on many technologically sophisticated areas such as telemedicine, microfluidics, drug delivery targeting, (bio)separation, labs-on-a-chip, textiles, power storage and release, environment monitoring, agro-food safety, cosmetics, architecture, automotive and so on. This book covers various topics, including the choice of materials and techniques for assembling responsive membranes with ability to transport mass, energy and signals on demand; the reader will find through the book an extensive description of the best techniques used to monitor molecular scale events, which are regarded as responsible for the smartness of multifunctional objects and for the conversion of chemical signals into optical, electrical, thermal and mechanical responses. The reader is encouraged to use this cross-disciplinary discussion for his own research. Chemical, biological and physical concepts, expressed through the book, contribute to form a common language, which will allow the reader to discover causes for reflection and innovation, measuring how smart objects with desired properties can be tailored from exiting materials and used flexibly for different developed applications. Specifically: This book deals with materials smartness and suitable techniques to assemble and characterize them in sensor-like membranes. This book shows how ultra-smart functional devices can be accomplished by using traditional raw materials. This book describes particular key events, which control 'sense to react and adapt' mechanisms. The potential of sensor-like membranes in some key strategic fields is examined with particular emphasis on biomedicine, food and textiles markets. The benefits arising from the use of smart membranes are analysed in terms of life quality, safety, and innovation.
Author: David Brutin Publisher: Academic Press ISBN: 0128008083 Category : Science Languages : en Pages : 464
Book Description
Droplet Wetting and Evaporation provides engineers, students, and researchers with the first comprehensive guide to the theory and applications of droplet wetting and evaporation. Beginning with a relevant theoretical background, the book moves on to consider specific aspects, including heat transfer, flow instabilities, and the drying of complex fluid droplets. Each chapter covers the principles of the subject, addressing corresponding practical issues and problems. The text is ideal for a broad range of domains, from aerospace and materials, to biomedical applications, comprehensively relaying the challenges and approaches from the different communities leading the way in droplet research and development. Provides a broad, cross-subject coverage of theory and application that is ideal for engineers, students and researchers who need to follow all major developments in this interdisciplinary field Includes comprehensive discussions of heat transfer, flow instabilities, and the drying of complex fluid droplets Begins with an accessible summary of fundamental theory before moving on to specific areas such as heat transfer, flow instabilities, and the drying of complex fluid droplets
Author: Robin H A Ras Publisher: Royal Society of Chemistry ISBN: 1782623957 Category : Science Languages : en Pages : 406
Book Description
The objective of this book is to integrate information about the theory, preparation and applications of non-wettable surfaces in one volume. By combining the discussion of all three aspects together the editors will show how theory assists the development of preparations methods and how these surfaces can be applied to different situations. The book is separated into three sections, first covering the theory, then going on to preparation of these surfaces and finally discussing the applications in detail. Edited by two of the most innovative contributors to the field of superhydrophobicity, this book will be essential reading for materials scientists interested in any aspect of surface, colloid and polymer science, thermodynamics, superhydrophobic and superhygrophobic surfaces.
Author: Bharat Bhushan Publisher: Springer Science & Business Media ISBN: 3540776087 Category : Technology & Engineering Languages : en Pages : 1530
Book Description
This volume serves as a timely, practical introduction to the principles of nanotribology and nanomechanics and applications to magnetic storage systems and MEMS/NEMS. Assuming some familiarity with macrotribology/mechanics, the book comprises chapters by internationally recognized experts, who integrate knowledge of the field from the mechanics and materials-science perspectives. Graduate students, research workers, and practicing engineers will find the book of value.
Author: Edward Yu. Bormashenko Publisher: Walter de Gruyter GmbH & Co KG ISBN: 3110583143 Category : Science Languages : en Pages : 200
Book Description
The revealing of the phenomenon of superhydrophobicity (the "lotus-effect") has stimulated an interest in wetting of real (rough and chemically heterogeneous) surfaces. In spite of the fact that wetting has been exposed to intensive research for more than 200 years, there still is a broad field open for theoretical and experimental research, including recently revealed superhydrophobic, superoleophobic and superhydrophilic surfaces, so-called liquid marbles, wetting transitions, etc. This book integrates all these aspects within a general framework of wetting of real surfaces, where physical and chemical heterogeneity is essential. Wetting of rough/heterogeneous surfaces is discussed through the use of the variational approach developed recently by the author. It allows natural and elegant grounding of main equations describing wetting of solid surfaces, i.e. Young, Wenzel and Cassie-Baxter equations. The problems of superhydrophobicity, wetting transitions and contact angle hysteresis are discussed in much detail, in view of novel models and new experimental data. The second edition surveys the last achievements in the field of wetting of real surfaces, including new chapters devoted to the wetting of lubricated and gradient surfaces and reactive wetting, which have seen the rapid progress in the last decade. Additional reading, surveying the progress across the entire field of wetting of real surfaces, is suggested to the reader. Contents What is surface tension? Wetting of ideal surfaces Contact angle hysteresis Dynamics of wetting Wetting of rough and chemically heterogeneous surfaces: the Wenzel and Cassie Models Superhydrophobicity, superhydrophilicity, and the rose petal effect Wetting transitions on rough surfaces Electrowetting and wetting in the presence of external fields Nonstick droplets Wetting of lubricated surfaces
Author: Alain Carré Publisher: CRC Press ISBN: 9004165932 Category : Science Languages : en Pages : 510
Book Description
Superhydrophobic surfaces (water contact angles higher than 150o) can only be achieved by a combination of hydrophobicity (low surface energy materials) with appropriate surface texture. In nature one can find an array of impressive and elegant examples of superhydrophobic surfaces. For example, on a lotus leaf rain drops bounce off after impact, then entirely roll off the lotus leaf and drag along any dirt particles, without leaving residues. The artificial design of superhydrophobic and self-cleaning surfaces has become an extremely active area of fundamental and applied research. This book presents both fundamental and applied aspects of superhydrophobic surfaces. It describes also different strategies for making superhydrophobic surfaces from a large diversity of materials (polymers, metals and other inorganic materials, composites) and processes (lithographic techniques, electrochemical processes, self-assembly processes, colloidal particles, sol-gel processes, nanofilaments, or simple scraping). A bountiful of information is covered in this book which represents cumulative wisdom of many world-renowned researchers in the fascinating and burgeoning area of superhydrophobic surfaces.
Author: Solomon E. Adera
Author: Solomon E. Adera
Author: Vincent Senez
Author: Hyuk-Min Kwon
Author: Annarosa Gugliuzza
Author: David Brutin
Author: Robin H A Ras
Author: Bharat Bhushan
Author: Edward Yu. Bormashenko
Author: Alain Carré
Author: Rajesh Leeladhar