Preface

There is apprehension about the undesirable material damage caused in devices by breakage, operational fatigue, volume change, abrasion, shape deformation, and cutting eventually formed during practical usage and degradation over time, resulting in deterioration of device properties. This mechanical damage of devices will reduce their reliability and shorten their lifespan. Thus, the development of suitable materials with self-healing, electrical and ionic properties to overcome the damage is very much the need of the hour. Self-healing smart materials (SHSMs) are one of the smart materials that can automatically restore some or all of a devices' functions after suffering external mechanical damage or harsh environments. In particular, because of their wide-ranging practical applications, SHSMs are having a significant impact in industry due to the self-healing capabilities of the material, which can expand the service life, operational life, longevity, and reliability of the devices; and also reduce waste, thereby conserving resources. The advancement of wearable electronic devices which use self-activating and self-adjusting systems are promising for enhancing operational safety and lifespan. Moreover, the use of SHSMs in manufacturing devices is an excellent choice to re-establish electrical and mechanical properties in case of a mechanical failure. Hence, an understanding about "self-healable technology" and all its related concepts is very essential for modern industries and research communities since these SHSMs and their composites are having a great impact on modern wearable applications in energy and environmental science.

This book describes the design, synthesis, mechanisms, characterization, fundamental properties, functions and development of SHSMs and their composites with their associated applications. It covers cementitious concrete composites, bleeding composites, elastomers, tires, membranes, and composites in energy storage, coatings, shape-memory, aerospace and robotic applications. This book is a result of the commitment of top researchers in the field with various backgrounds and expertise. Its target audience includes materials scientists, polymer industrialists, researchers, members of R&D in wearable electronics; as well as university professors, postgraduate students and academics who are working and studying in the fields of polymers, chemical technology, biology, advanced electronics, polymer engineering, aeronautical engineering. mechanical engineering, biomedicine, advanced sciences, materials sciences, flexible energy storage, and renewable energy. A summary of the information covered in the 21 chapters is given below.

Chapter 1 describes the most recent and relevant advances in the development of self-healable polymer coatings, both extrinsic (those using external healing agents) and intrinsic. Implementation of new strategies, like remote activation of the healing process, as well as the perspectives and challenges for these innovative materials, are also discussed.

Chapter 2 overviews the current progress on the synthesis of benzoxazine-based materials for self-healing and shape-memory applications. The advantages and drawbacks of these materials are also discussed. Many examples are provided regarding the design flexibility of benzoxazine chemistry and its vast potential in designing smart materials.

Chapter 3 introduces the characteristics of self-healing in elastomers and techniques for characterization of healing ability. It also reviews self-healing in particular cases of different elastomer matrices such as natural rubber (NR), styrene butadiene rubber (SBR), polybutadiene rubber (BR), bromobutyl rubber (BIIR), silicones and polyurethane (PU).

Chapter 4 discusses various promising strategies for fabricating self-healable rubber as well as methods to improve the self-recovery properties of the rubber. In addition to that, the chapter also focuses on natural rubber modification with self-healing properties, as it has become the most critical component in manufacturing self-healable tires.

Chapter 5 outlines the self-healing methods for concrete composites in general, and details about bacterial-aided, self-healing in particular. The different mechanisms of bacterial self-healing and the factors influencing it are discussed. Strategies to enhance the performance of the healing, as well as methods employed for testing are also included.

Chapter 6 focuses on an ideal and long-lasting photovoltaic device which can heal all of the damages applied to its structure to decrease maintenance costs of solar panels. The current self-healing mechanisms and recent progress in solar cells are summarized.

Chapter 7 provides additional insights into the construction of self- healable core-shell nanofiber agents and their potential application in various areas.

Chapter 8 details the state-of-the-art in intrinsic self-healing smart materials. It summarizes some of the most significant research on SHSMs.

Future challenges that need to be overcome to enable commercial exploration of systems already developed are also discussed.

Chapter 9 discusses self-healable materials in the field of catalysis. The basics and application areas of catalysts that are reported in the literature are covered. Additionally, some specific energy fields, such as oxygen evolution and hydrogen generation catalysts, are discussed in detail.

Chapter 10 details the recent advances regarding the potential applications of various types of micro/nano-carriers of healing agents for the development of smart/intrinsic self-healing anti-corrosion polymeric coatings. The SHSMs/fillers classification, various techniques used to load inhibitors into carriers/containers, and their release/corrosion-inhibition mechanisms are introduced and conceptualized.

Chapter 11 discusses the various methods of self-healing for conductive materials. Self-healing conductive materials, such as elastomers, reversible bonds, polymers, capsules, liquids and composite, are discussed. The complex conductivity which can be established even as a coating is also discussed.

Chapter 12 deals with the preparation and properties of self-healable electronic skin. Its various applications as a pressure sensor and body motion sensor are discussed. Artificial skin can also be used for electrocardiogram and electromyograph monitoring, as well as for monitoring Parkinson's tremor.

Chapter 13 overviews self-healing smart composite materials and their different self-healing mechanisms. These materials are designed based on two approaches: (a) discharge of smart self-healing agents towards the generated damage and (b) alterable crosslinking networks.

Chapter 14 overviews the stimuli-responsive self-healable materials. It provides details about the history, different types and importance of self-healable materials. The major focus is on recent examples of self-healing polymers that show response to various stimuli. The chapter ends with a discussion about aspects concerning the commercialization of SHSMs and challenges in the area.

Chapter 15 covers mechanically-induced SHSMs with novel characteristics for numerous applications. Various methods of producing these mechanically-induced SHSMs based on different types of materials are discussed.

Chapter 16 discusses SHSMs, their method of synthesis, and application in robotics. The focus of the chapter is on describing the chemistry of self-healing and the working principles. The various approaches of self-healing are also explained such as capsule-based, vascular, and intrinsic self-healing systems. The major focus is on the application of the material in the different sections of soft robots such as skin, actuator, electronics, and sensor.

Chapter 17 discusses the various methods of developing SHSMs for aerospace structural and high-temperature applications. Materials like fiber-reinforced polymers that alter the nature of the base matrix and ceramic matrix composites are described in detail along with intrinsic and extrinsic self-healing mechanisms.

Chapter 18 presents bioinspired, magnificent, nature-based, broadscope elements with numerous functions. These elements exhibit immense power to perceive, respond, and self-heal (autonomous healing). The discussion proceeds with a brief insight into SHSMs, coatings, their types, and the exploitation process used to extract their characteristic features to benefit humankind. This chapter sheds more light on examples dealing with self-healable materials with a notion to fabricate such self-healable materials with rapid exploration and a promising platform.

Chapter 19 introduces SHSMs as promising candidates for the fabrication of electronic devices, energy storage systems, and even sensors. The progress made in SHSMs research is detailed and the preparation mechanisms and properties of the self-healing processes are summarized. In terms of self-healing batteries, both macroscopic and microscopic SHSMs are introduced.

Chapter 20 focuses on self-healing in bleeding engineered composite structures. Additionally, materials with intrinsic and extrinsic self-healing properties are discussed. Moreover, various strategies like bioinspired, biomimetic and vascular networks, are described in detail. Also discussed are approaches for the synthesis of bleeding composite structures, along with their evolved properties, repairing mechanism, disadvantages, and advantages.

Chapter 21 provides a general overview of numerous materials with self-healing attributes. Greater...