Research on self-healing materials spans multiple academic disciplines and employs a variety of methodologies. Nature has been a major source of inspiration for developing self-healing materials and will likely continue to inspire innovative ideas in this field. This review article covers the principles of self-healing mechanisms, focusing on both autonomous and non-autonomous procedures. It explores both intrinsic and extrinsic self-healing abilities by considering their components, structures, and design. Additionally, a detailed analysis of the application of these materials across various sectors is provided, including aerospace, automotive, marine, energy, medical and healthcare, military, and construction. Finally, the review paper highlights the advancements in encapsulation technologies for microcapsules, their thermal stability, their mechanical properties, and the compatibility of healing agents with the matrix, which play a crucial role in the effectiveness of self-healing processes.

This article provides a brief description of microcapsule self-healing technique and its potential use in concrete structures. Because concrete is readily available and reasonably priced, it is widely utilised in the building industry globally, despite its susceptibility to the formation of cracks. The longevity and security of concrete buildings are greatly impacted by the existence of cracks and other deterioration occurring during the course of their use. Through the encapsulation of healing material inside microcapsules, which shows rupture upon cracking in cement-based materials, the microcapsule exhibits promise in accomplishing self-healing and increasing durability and strength in the structures. The article first explains the basic ideas behind the science of microcapsule self-healing and then looks at different ways to prepare microcapsules. It also looks into how adding microcapsules affects the basic characteristics of the concrete building. A summary of the efficiency and self-healing mechanisms of microcapsules is also provided.
The article explains the advantages of the microcapsule self-healing method in concrete.Preparation method and intrinsic properties of different microcapsules are discussed.Different self-healing measurement techniques in cement-based materials are discussed.The study examines the qualitative aspects of various self-healing methods.Looks into how adding microcapsules affects the properties of cementitious materials.

Hydrogels made from conductive organic materials have gained significant interest in recent years due to their wide range of uses, such as electrical conductors, freezing resistors, biosensors, actuators, biomedical engineering materials, drug carrier, artificial organs, flexible electronics, battery solar cells, soft robotics, and self-healers. Nevertheless, the insufficient level of effectiveness in electroconductive hydrogels serves as a driving force for researchers to intensify their endeavors in this domain. This article provides a concise overview of the recent advancements in creating self-healing single- or multi-network (double or triple) conductive hydrogels (CHs) using a range of natural and synthetic polymers and monomers. We deliberated on the efficacy, benefits, and drawbacks of several conductive hydrogels. This paper emphasizes the use of natural polymers and innovative 3D printing CHs-based technology to create self-healing conductive gels for flexible electronics. In conclusion, advantages and disadvantages have been noted, and some potential opportunities for self-healing single- or multi-network hydrogels have been proposed.

Resin-based dental composites, commonly used in dentistry, offer several advantages including minimally invasive application, esthetically pleasing appearance, and good physical and mechanical properties. However, these dental composites can be susceptible to microcracks due to various factors in the complex oral environment. These microcracks can potentially lead to clinical restoration failure. Conventional materials and methods are inadequate for detecting and repairing these microcracks in situ. Consequently, incorporating self-healing properties into dental composites has become a necessity. Recent years have witnessed rapid advancements in self-healing polymer materials, drawing inspiration from biological bionics. Microcapsule-based self-healing dental composites (SHDCs) represent some of the most prevalent types of self-healing materials utilized in this domain. In this article, we undertake a comprehensive review of the most recent literature, highlighting key insights and findings related to microcapsule-based SHDCs. Our discussion centers particularly on the preparation techniques, application methods, and the promising future of self-healing microcapsules in the field of dentistry.

Covalent adaptable networks and vitrimers are novel polymers with dynamic reversible bond exchange reactions for crosslinks, enabling them to modulate their properties between those of thermoplastics and thermosets. They have been gathering interest as materials for their recycling and self-healing properties. In this review, we discuss different molecular simulation efforts that have been used over the last decade to investigate and understand the nanoscale and molecular behaviors of covalent adaptable networks and vitrimers. In particular, molecular dynamics, Monte Carlo, and a hybrid of molecular dynamics and Monte Carlo approaches have been used to model the dynamic bond exchange reaction, which is the main mechanism of interest since it controls both the mechanical and rheological behaviors. The molecular simulation techniques presented yield sufficient results to investigate the structure and dynamics as well as the mechanical and rheological responses of such dynamic networks. The benefits of each method have been highlighted. The use of other tools such as theoretical models and machine learning has been included. We noticed, amongst the most prominent results, that stress relaxes as the bond exchange reaction happens, and that at temperatures higher than the glass transition temperature, the self-healing properties are better since more bond BERs are observed. The lifetime of dynamic covalent crosslinks follows, at moderate to high temperatures, an Arrhenius-like temperature dependence. We note the modeling of certain properties like the melt viscosity with glass transition temperature and the topology freezing transition temperature according to a behavior ruled by either the Williams-Landel-Ferry equation or the Arrhenius equation. Discrepancies between the behavior in dissociative and associative covalent adaptable networks are discussed. We conclude by stating which material parameters and atomistic factors, at the nanoscale, have not yet been taken into account and are lacking in the current literature.

The development of materials with self-healing capabilities has garnered considerable attention due to their potential to enhance the durability and longevity of various engineering and structural applications. In this review, we provide an overview of recent advances in materials with self-healing properties, encompassing polymers, ceramics, metals, and composites. We outline future research directions and potential applications of self-healing materials (SHMs) in diverse fields. This review aims to provide insights into the current state-of-the-art in SHM research and guide future efforts towards the development of innovative and sustainable materials with enhanced self-repair capabilities. Each material type showcases unique self-repair mechanisms tailored to address specific challenges. Furthermore, this review investigates crack healing processes, shedding light on the latest developments in this critical aspect of self-healing materials. Through an extensive exploration of these topics, this review aims to provide a comprehensive understanding of the current landscape and future directions in self-healing materials research.

In recent years, the adhesive technology has been widely used in the production of high-strength joins and precise positioning of various materials, such as metals, glass and composite materials. The adhesive technology has become a promising assembly process in the aerospace field due to its versatility, low creep and high damage tolerance. However, the reliability and predictability of adhesive bonding still require further development due to the complex operating conditions involved. Therefore, this article reviews and discusses the latest advances in aerospace adhesive technology, such as methods for improving bonding performance, bonding techniques (including joints structure and failure modes) and self-healing adhesive layers. Additionally, the current research results are summarised, and possible development trends and research directions in the field of adhesive bonding are prospected.

Different types of clinical wounds are difficult to treat while infected by bacteria. Wound repair involves multiple cellular and molecular interactions, which is a complicated process. However, wound repair often suffers from abnormal cellular functions or pathways that result in unavoidable side effects, so there is an urgent need for a material that can heal wounds quickly and with few side effects. Based on these needs, hydrogels with injectable properties have been confirmed to be able to undergo self-healing, which provides favorable conditions for wound healing. Notably, as a biopolymer with excellent easy-to-modify properties from a wide range of natural sources, chitosan can be used to prepare injectable hydrogel with multifunction for wound healing because of its outstanding flowability and injectability. Especially, chitosan-based hydrogels with marked biocompatibility, non-toxicity, and bio-adhesion properties are ideal for facilitating wound healing. In this review, the characteristics and healing mechanisms of different wounds are briefly summarized. In addition, the preparation and characterization of injectable chitosan hydrogels in recent years are classified. Additionally, the bioactive properties of this type of hydrogel in vitro and in vivo are demonstrated, and future trend in wound healing is prospected.

Concrete is the main ingredient in construction, but it inevitably fractures during its service life, requiring a large amount of cement and aggregate for maintenance. Concrete healing through biomineralization can repair cracks and improve the durability of concrete, which is conducive to saving raw materials and reducing carbon emissions. This paper reviews the biodiversity of microorganisms capable of precipitating mineralization to repair the concrete and their mineralization ability under different conditions. To better understand the mass transfer process of precipitates, two biomineralization mechanisms, microbially-controlled mineralization and microbially-induced mineralization, have been briefly described. The application of microorganisms in the field of healing concrete, comprising passive healing and intrinsic healing, is discussed. The key insight on the interaction between cementitious materials and microorganisms is the main approach for developing novel self-healing concrete in the future to improve the corrosion resistance of concrete. At the same time, the limitations and challenges are also pointed out.

Self-healing polymeric materials, engineered to autonomously self-restore damages from external stimuli, are at the forefront of sustainable materials research. Their ability to maintain product quality and functionality and prolong product life plays a crucial role in mitigating the environmental burden of plastic waste. Historically, initial research on the development of self-healing materials has focused on extrinsic self-healing systems characterized by the integration of embedded healing agents. These studies have primarily focused on optimizing the release of healing agents and ensuring rapid self-healing capabilities. In contrast, recent advancements have shifted the focus towards intrinsic self-healing systems that utilize their inherent reactivity and interactions within the matrix. These systems offer the advantage of repeated self-healing over the same damaged zone, which is attributed to reversible chemical reactions and supramolecular interactions. This review offers a comprehensive perspective on extrinsic and intrinsic self-healing approaches and elucidates their unique properties and characteristics. Furthermore, various self-healing mechanisms are surveyed, and insights from cutting-edge studies are integrated.