Self-Healing Materials Hager, Martin D.; Greil, Peter; Leyens, Christoph ...
Advanced materials (Weinheim),
December 14, 2010, Letnik:
22, Številka:
47
Journal Article
Recenzirano
Self‐healing materials are able to partially or completely heal damage inflicted on them, e.g., crack formation; it is anticipated that the original functionality can be restored. This article covers ...the design and generic principles of self‐healing materials through a wide range of different material classes including metals, ceramics, concrete, and polymers. Recent key developments and future challenges in the field of self‐healing materials are summarised, and generic, fundamental material‐independent principles and mechanism are discussed and evaluated.
Self‐healing materials are able to partially or completely heal damage inflicted on them, e.g., crack formation; it is anticipated that the original functionality of self‐healed materials can be restored. This behavior can be applied across a wide range of different material classes including metals, ceramics, concrete, and polymers.
Inspired by naturally occurring species that allow for self-healing of nonfatal harm, self-healing polymeric materials have been prepared and represent a component of the intelligent materials ...family. These materials possess the inherent ability to rehabilitate damage produced during manufacturing and/or usage. The self-healing methodologies developed to date can be classified as intrinsic or extrinsic according to the method used to deliver the healing components to the target site in the material. Intrinsic self-healing operates through inter- or intra-macromolecular interactions, whereas extrinsic self-healing makes use of a pre-embedded healing agent. Extrinsic self-healing can be more easily realized in commercially available polymers because no structural modification of the matrix molecules is required. In recent years, extrinsic self-healing based on microencapsulated healing agents has attracted growing interest. Extrinsic self-healing in a variety of materials (including thermosets, thermoplastics, rigid, and elastomeric materials) has been demonstrated and offers recovery of both mechanical and non-structural functional properties. Self-healing based on microcapsules can deliver further results if combined with intrinsic self-healing. Using a bottom-up perspective, the current article presents a comprehensive review of recent progress in this field from the viewpoint of material design and preparation. The topics presented include (i) a basic overview of self-healing systems, (ii) microencapsulation techniques (e.g., in situ polymerization, interfacial polymerization, Pickering emulsion templating, miniemulsion polymerization, solvent evaporation/solvent extraction, sol–gel reaction, etc.), (iii) crack response of microcapsules, and (iv) healing chemistries (e.g., ring-opening metathesis polymerization, polycondensation, anionic ring opening polymerization, cationic polymerization, free radical polymerization, addition reaction, etc.). The strengths and weaknesses of each microencapsulation technique and type of healing chemistry are analyzed and compared. Additionally, formulation optimization (including species of healing agent and wall substance of capsules), processing, structure and property relationship, healing mechanisms, and stability are discussed. Trends and challenges are summarized at the end of the review. The scope of this review is to provide the reader with an overview of achievements to date and insight into future development for engineering applications.
An extrinsic self‐healing coating system containing tetraphenylethylene (TPE) in microcapsules was monitored by measuring aggregation‐induced emission (AIE). The core healing agent comprised of ...methacryloxypropyl‐terminated polydimethylsiloxane, styrene, benzoin isobutyl ether, and TPE was encapsulated in a urea‐formaldehyde shell. The photoluminescence of the healing agent in the microcapsules was measured that the blue emission intensity dramatically increased and the storage modulus also increased up to 105 Pa after the photocuring. These results suggested that this formulation might be useful as a self‐healing material and as an indicator of the self‐healing process due to the dramatic change in fluorescence during photocuring. To examine the ability of the healing agent to repair damage to a coating, a self‐healing coating containing embedded microcapsules was scribed with a razor. As the healing process proceeded, blue light fluorescence emission was observed at the scribed regions. This observation suggested that self‐healing could be monitored using the AIE fluorescence.
An extrinsic self‐healing coating containing tetraphenylethylene in microcapsules is monitored by aggregation‐induced emission (AIE). As the healing process proceeds, blue fluorescence is observed at scribed region. Self‐healing can be monitored using the AIE.
Traditional electronic devices inevitably undergo degradation over time due to deformation, fatigue, or mechanical damage, ultimately resulting in device failure. To overcome this issue, researchers ...have pioneered the field of elastic electronics, incorporating higher mechanical tensile properties or strain resistance into electronic devices. Elastic materials, especially self‐healing elastomers (SHEs) are regarded as a crucial component in elastic electronics, offering the potential for restoring functionality and prolonging the lifespan of electronic devices. SHEs possess remarkable ability to tolerate significant deformation and utilize intrinsic dynamic chemical bonds to autonomously repair themselves from varying degrees of damage. The acquisition of intrinsic SHEs is key to the development of self‐healing elastic electronics and has attracted global attention. This review offers a comprehensive overview of the current advancements in self‐healing elastic electronics. First, the various self‐healing mechanisms present in elastomeric material systems are summarized. Second, the design strategies for constructing SHEs based on self‐healing mechanisms are reviewed in detail, with a particular emphasis on dynamic covalent and non‐covalent bonds. Subsequently, various optoelectronic applications of SHEs in elastic electronics are summarized. Finally, the challenges and prospects that lie ahead in order to foster further development in this rapidly growing field are outlined.
In recent years, significant advancements have been made in self‐healing elastic electronics, including the design of self‐healing elastomers and corresponding elastic optoelectronic devices. Herein, a detailed and comprehensive overview of material design strategies including dynamic covalent/non‐covalent bonds is provided, and various optoelectronic applications including e‐skins, field effect transistors, energy storage devices, perovskite solar cells, and electroluminescent devices.
Self-healing polymer composites possess the inherent ability to heal the damage event autonomically or non-autonomically with external intervention. These advanced materials can be commercialized if ...the challenges and limitations of different self-healing mechanisms are well known and considered. These include capsule-based healing systems, vascular healing systems, and intrinsic healing systems. To date, most of the reviews have studied and reported on different self-healing mechanisms including their response to impact, fatigue, and corrosion tests. This review focuses mostly on extrinsic and intrinsic self-healing polymer composites which have been reported during the past five years by comparing their healing efficiency, advantages, and challenges in the prospect of their future development as well as their possible applications across various industries such as aerospace, automobile, coating, electronics, energy, etc.
The effect of structural parameters such as hard segment content and cross‐linking degree on the mechanical properties of waterborne self‐healing polyurethane and the effect of tensile strength, ...self‐healing conditions (temperature, time) on the self‐healing properties were investigated. These results demonstrated that as the increasing of the content of hard segments/the cross‐linking agent, the tensile strength of the sample increased and the self‐healing performance exhibited a downward trend. When the tensile strength reached 40 MPa, it could hardly healed, even if prolonging the self‐healing time or increasing the self‐healing temperature. Mechanism study demonstrated that the self‐healing ability was attributed to the dynamic exchange of disulfide bonds and the thermal reversibility of hydrogen bonds in the system. Hydrogen bonding could provide the initial self‐healing force and promote the dynamic exchange reaction of disulfide bonds, while high hydrogen bonding is not conducive to the movement of macromolecular segments, causing a decrease in the self‐healing efficiency.
