Superhydrophobic Coatings Of Wax And Polymers Sprayed From Supercritical Solutions

The possibility of using supercritical carbon dioxide (scCO2) as the primary solvent in a spray process for producing superhydrophobic surfaces have been examined in this work. Using scCO2 as solvent will have considerably lower environmental impact compared to an organic solvent since scCO2 is considered a green solvent as it is non-toxic, non-flammable and recyclable. To be able to work at the pressures needed to reach the supercritical state of carbon dioxide, a high-pressure technique called rapid expansion of supercritical solutions (RESS) has been used to produce the coatings. Fluorinated compounds are often used when producing superhydrophobic coatings due to their intrinsic water repellent properties, but generally these compound do not degrade in nature. Due to this, a wax and a biodegradable polymer have been used as the coating materials in this work. Two RESS set-ups were used to spray a polymer from solutions of scCO2 and acetone. The first system was based on a continuous flow of the solvent mixture and the polymer particles were collected on silica surfaces. Some of the coatings had superhydrophobic properties and the limitation with this technique was the loss of particles between the nozzle and the surface. In the second set-up, RESS was combined with electrostatic deposition (ED) to improve the particle collection. Different processing parameters were examined and most of the RESS-ED sprayed surfaces were superhydrophobic. This was demonstrated by high contact angles against water, low contact angle hysteresis and low tilt angles at which a water droplet rolls off the surface. It was also shown that the surface structures created when spraying using RESS-ED induced the important two-level roughness that was needed to achieve superhydrophobicity. A semi-continuous process for scaling-up the RESS system when spraying the wax has been developed. Temperature and pressure was investigated to find the highest solubility of the wax in scCO2, and 250 bar and 67 °C resulted in the largest amount of sprayed wax. It was also shown that the system is suitable for spray-coating the wax on different substrates such as glass, paper, aluminium etc. since all of these surfaces showed superhydrophobic properties. The wear resistance of the coatings were examined by different methods. Scratch resistance, vertical compression and the friction between the surface and a finger were analysed. The polymer coated surfaces showed a larger robustness compared with the wax surfaces in the scratch tests. The superhydrophobicity was lost for the wax coatings exposed to compression loads above 59 kPa and in the frictions test, one finger stroke over the coating destroyed the surface roughness. Finally, the wax surfaces were investigated as coating barriers to protect steel from corrosion. The superhydrophobic coating was stable up to 10 days before corrosion of the steel started.

This book guides readers through superhydrophobic coating fabrication and thier application, representing the latest significant advances in this important topic.

The recent huge developments in nanotechnology and surface science are allowing the production of multifunctional coatings materials combining different properties: corrosion-protective actions, aesthetic functions, hydrophobic properties, self-healing abilities, etc. Moreover the increasing attention to environmental issues is driving the development of new systems, joining advanced performance with high sustainability, which can be better understood using new highly efficient experimental techniques. This frame is inducing us to consider the advances in organic coatings (the skin of materials) as one of the most interesting and promising innovation fields in material science and technology, with important consequences, not only considering fundamental aspects in science, but also for industrial applications, positively affecting everyday life. The aim of this Special Issue is to provide an update of the most advanced research in this area, showing the innovation trends and promoting further research for better properties of new coating materials.

This book investigates the enhancement of properties of acacia wood and its surface treatment for high strength bio-composites. It describes the tensile, flexural and impact strength, surface behaviour, morphological analysis, infrared spectral functional analysis, thermal properties analysis and dielectrical properties of acacia wood bio-composites. It reports efforts on the optimization of fabrication techniques to prepare acacia wood reinforced bio-composites based on PLA, PHA, Etc. The book also reports on environmental impact analysis of acacia wood bio-composites. A special chapter is dedicated to the nano-enhancement of acacia wood bio-composites and their possible use in applications in terms of sustainability and economics.

Nanocellulose Based Composites for Electronics presents recent developments in the synthesis and applications of nanocellulose composites in electronics, highlighting applications in various technologies. Chapters covers new trends and challenges in a wide range of electronic applications and devices. Significant properties, safety, sustainability, and environmental impacts of the electronic devices are included, along with the challenges of using nanocellulose-based composites in electronics. This book is an important reference for materials scientists and engineers configuring and designing processes for the synthesis and device fabrication of nanocellulose composites in electronics. Explores how to utilize nanocellulose fibers and nano-crystalline cellulose substances to synthesize materials with designed functionalities Outlines the major production processes for nanocellulous composites Discusses the major challenges that need to be surmounted in order to effectively use nanocellulous composites for electronics

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.

Biopolymers and Their Industrial Applications: From Plant, Animal, and Marine Sources to Functional Products is a detailed guide to the use of biopolymers for advanced applications across a range of key industries. In terms of processing and cost, bio-based polymers are becoming increasingly viable for an ever-broadening range of novel industrial applications. The book begins with an overview of biopolymers, explaining resources, demands, sustainability, life cycle assessment (LCA) modeling and simulation, and classifications. Further in-depth chapters explore the latest techniques and methodologies for isolation and physicochemical characterization, materials selection, and processing for blends and composites. Chapters 6 to 14 each focus on the preparation and applications of biopolymers in a specific industrial area, including food science and nutraceuticals, medicine and pharmaceuticals, textiles, cosmeceutical, packaging, adhesives and automotive, 3D printing, super capacitor and energy storage devices, and environmental applications. The final chapter compares and analyzes biopolymers alongside synthetic polymers, also offering valuable insight into social, economic, and environmental aspects. This is an essential resource for those seeking to understand, research, or utilize biopolymers in industrial applications. This includes researchers, scientists, and advanced students working in biopolymers, polymer science, polymer chemistry, biomaterials, materials science, nanotechnology, composites, and biotechnology. This is a highly valuable book for scientists, R&D professionals, designers, and engineers across multiple industries and disciplines, who are looking to utilize biopolymers for components and products. Introduces a broad range of industrial application areas, including food, medicine, textiles, cosmetics, packaging, automotive, 3D printing, energy, and more Offers an industry-oriented approach, addressing challenges and explaining the preparation and application of biopolymers for functional products and parts Considers important factors such as resources, classification, sustainability, and life cycle assessment (LCA) modeling and simulation Compares and analyzes biopolymers alongside synthetic polymers, also offering valuable insight into social, economic, and environmental aspects