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Mixtures of sorbitol polyglycidyl ether (SPE) and poly(ethylene glycol) diglycidyl ether (PEGDGE) were cured with cystamine (CTA) to produce bio-based amine-cured epoxy resins (SPE-PEGDGE-CTA) containing disulfide bonds. Furthermore, the SPE was cured with 3,3′-dithiodipropionic acid (DTDPA) and citric acid (CA) to produce bio-based carboxy-cured epoxy resins (SPE-DTDPA-CA) containing disulfide bonds. Fourier transform infrared spectroscopy (FT-IR) of the cured products revealed that the epoxy–amine and epoxy–carboxy curing reactions proceeded almost completely. The glass transition temperature (Tg) and mechanical strength of the amine-cured products decreased with increasing PEGDGE fraction, and those of the carboxy-cured products decreased with increasing DTDPA fraction. The amine-cured product with the highest CTA fraction and all carboxy-cured products were healed three times at 80 ℃, whereas none of the corresponding cured products without disulfide bonds exhibited self-healing properties. The maximal healing efficiencies of the amine- and carboxy-cured products in terms of tensile strength were 84% and 91%, respectively. [ABSTRACT FROM AUTHOR]

With the rapid economic development in recent years, there has been an increasing demand for durable and high-performance transportation road pavements. Polymer-modified asphalt has gained widespread acceptance due to its ability to enhance driving comfort and extend service life. Nevertheless, the longevity of asphalt pavements is often compromised by long-term traffic loads and harsh weather conditions, leading to cracking and degradation. To tackle this issue, dynamic chemistry introduces a promising solution for self-healing polymer-modified asphalt. By integrating dynamic bonds into the polymers structure, its network becomes adaptable to external triggers such as pressure, temperature, and pH, enabling material self-repair via dynamic healing mechanisms. This paper explores the synthesis methods and structural characteristics of dynamic self-healing polymers, their impact on the self-healing performance of modified asphalt and the classification of dynamic bonds. Additionally, the paper discusses methods for evaluating the self-healing performance and identifies future challenges and research directions for self-healing polymer-modified asphalt materials. [ABSTRACT FROM AUTHOR]

A series of novel network polymers P1-P6 and Pn-Znx:y based on metal–ligand coordination bonds with different strength were prepared by one pot method. The structures of the polymers were confirmed by NMR and FT-IR spectra. The amorphous structure of polymers was determined by X-ray diffraction analysis with only broad scattering peaks detected. The TGA and DSC showed that the increase of pyridyl group can dramatically improve the thermal stability of polymers, and Tg gradually decreases with the increase of pyridyl and pyridine groups. When the amount of Zn(II) increases, the thermal stability and the Tg gradually decreases. Optical microscope images indicated that the cross-linked network polymers Pn-Zn1:2 all had obvious self-healing properties at room temperature, and the 50% cross-linked network P3-Zn1:2 and P4-Zn1:2 with less pyridine content have better self-healing performance. Further exploration of the self-healing properties of P3-Znx:y by adjusting the molar ratio of dianhydride to Zn(II), P3-Zn1:4 has the best self-healing performance. [ABSTRACT FROM AUTHOR]

This comprehensive review addresses the self‐healing phenomenon in perovskite solar cells (PSCs), emphasizing the reversible reactions of dynamic bonds as the pivotal mechanism. The crucial role of polymers in both enhancing the inherent properties of perovskite and inducing self‐healing phenomena in grain boundaries of perovskite films are exhibited. The review initiates with an exploration of the various stability problems that PSCs encounter, underscoring the imperative to develop PSCs with extended lifespans capable of self‐heal following damage from moisture and mechanical stress. Owing to the strong compatibility brought by polymer characteristics, many additive strategies can be employed in self‐healing PSCs through artful molecular design. These strategies aim to limit ion migration, prevent moisture ingress, alleviate mechanical stress, and enhance charge carrier transport. By scrutinizing the conditions, efficiency, and types of self‐healing behavior, the review encapsulates the principles of dynamic bonds in the polymers of self‐healing PSCs. The meticulously designed polymers not only improve the lifespan of PSCs through the action of dynamic bonds but also enhance their environmental stability through functional groups. In addition, an outlook on self‐healing PSCs is provided, offering strategic guidance for future research directions in this specialized area. [ABSTRACT FROM AUTHOR]

Fatigue performance and self-repairing activity of asphalt binders are two properties that highly influence the fatigue cracking response of asphalt pavement. There are still numerous gaps in knowledge to fill linked with these two characteristics. For instance, current parameters fail to accommodate these two bitumen phenomena fully. This study aims to propose a new procedure to address this issue utilizing the linear amplitude sweep (LAS) test, LAS with rest period (RP) (LASH) test, and simplified viscoelastic continuum damage (S-VECD) model. This research work used four different types of asphalt binders: neat asphalt (NA), self-healing thermoplastic polyurethane (STPU)-modified bitumen (STPB), self-healing poly (dimethyl siloxane) crosslinked with urea bond (IPA1w)-modified bitumen (IPAB), and styrene–butadiene–styrene (SBS)-modified bitumen (SBSB). Before the testing process, all the materials were subjected to short-term and long-term aging. The new procedure showed a superior capacity to analyze and accommodate all bitumen fatigue performances and self-repairing activities compared to the current method. Another finding proved that asphalt binders with a higher self-restoration behavior failed to show a better fatigue performance. Moreover, the higher fatigue performance increments produced by STPU and IPA1w in NA concerning the control bitumen were 123.7% and 143.7%, respectively. Those values were obtained with 1.0% STPU and 0.5% IPA1w in NA. A breakthrough finding demonstrated that asphalt binder fatigue response is augmented when the RP was applied at a higher damage intensity (S) value. STPB and IPAB reached their highest increments of fatigue response, containing 1.0% of STPU and 0.5% of IPA1w, respectively. Those augmentations were 207.54% and 232.64%, respectively. [ABSTRACT FROM AUTHOR]

Healthcare devices play an important role in the diagnosis, treatment, and monitoring of patients. MXene, as a new member of the two-dimensional materials family, has characteristic conductivity, hydrophilicity, biocompatibility, and antibacterial ability, which makes it suitable for fabricating healthcare devices. By combining MXene with self-healing polymers, durable and self-healing healthcare devices that are resistant to mechanical damage during dynamic work can be achieved. Thanks to the dual biocompatibility of MXene and polymers, the self-healing MXene/polymer composites have the functions of sensing and self-healing in vivo and in vitro, serving as a basis for modern healthcare devices. Herein, we summarize the recent progress of using MXene/polymer composites to fabricate skin-friendly sensors with self-healing capability: universal strategies for fabricating self-healing MXene sensors and their fundamental performance are discussed, and biomedical healthcare applications are demonstrated. This review aims to provide a reference for MXene-based self-healing healthcare electronics and facilitate further efforts in the innovation of modern biomedical devices. [ABSTRACT FROM AUTHOR]

Polymeric foams derived from bio‐based resources and capable of self‐healing and recycling ability are of great demand to fulfill various applications and address environmental concerns related to accumulation of plastic wastes. In this article, a set of polyester‐based covalent adaptable biofoams (CABs) synthesized from carbohydrates and other bio‐derived precursors under catalyst free conditions to offer a sustainable alternative to conventional toxic isocyanate‐based polyurethane foams is reported. The dynamic β‐keto carboxylate linkages present in these biofoams impart self‐healing ability and recyclability to these samples. These CABs display adequate tensile properties especially compressive strength (≤123 MPa) and hysteresis behavior. The CABs swiftly stress relax at 150 °C and are reprocessable under similar temperature conditions. These biofoams have displayed potential for use as attachment on solar photovoltaics to augment the output efficiency. These CABs with limited swellability in polar protic solvents and adequate mechanical resilience are suitable for other commodity applications. [ABSTRACT FROM AUTHOR]

Abstract Over the past 10 years, perovskite solar cell (PSC) device technologies have advanced remarkably and exhibited a notable increase in efficiency. Additionally, significant innovation approaches have improved the stability related to heat, light, and moisture of PSC devices. Despite these developments in PSCs, the instability of PSCs is a pressing problem and an urgent matter to overcome for practical application. Recently, polymers have been suggested suggestion has been presented to solve the instability issues of PSCs and increase the photovoltaic parameters of devices. Here, first, the fundamental chemical bond types of self‐healing polymers are presented. Then, a comprehensive presentation of the ability of self‐healing polymers in rigid and flexible PSCs to enhance the various physical, mechanical, and optoelectronic properties is presented. Furthermore, valuable insights and innovative solutions for perovskite‐based optoelectronics with self‐healing polymers are provided, offering guidance for future optoelectronic applications.

In this study, we promote a multi-scale modeling to predict the healing efficiencies (HEs) of incorporated polymers with self-healing microcapsules. The Python scripts were employed to generate three representative volume elements (RVEs) with randomly dispersed 5, 7.5, and 10% volume fraction (VF) of alginate microcapsules. Three VUSDFLD subroutines were codded and supplemented with ABAQUS/Explicit solver to obtain the maximum tensile stresses (Sut) of virgin, damaged, and healed samples followed by calculating HF of self-healing polymers. Based on the simulation results, more incorporation of self-healing microcapsules increased the tensile after impact HF, so that HFs were increased from 46.31% for RVEs containing 5% VF up to 65.41% and 84.84% for 7.5% and 10% VF, respectively. The presence of more self-healing microcapsules could improve the chance of rupturing more filled microcapsules with healing agents after crack propagation due to impact damages in the matrix. Thus, more damaged elements would be healed by spread healing agents. To evaluate the reliability of simulation results, the specimens containing electrosprayed multicore self-healing microcapsules were fabricated, and experimental HFs were calculated. The same trend was obtained for experimental results, as acquired in the simulation of RVEs. The error of healing efficiencies were only 6.82%, 2.81%, and 7.74 for incorporated specimens with 5, 7.5, and 10% VF of electrosprayed multicore microcapsules, respectively, indicating the accuracy of introduced multi-scale finite element modeling. The fabrication defects of experimental specimens can be the reason of simulation errors. [ABSTRACT FROM AUTHOR]

Regulation of phase structure has been recognized as one of the most effective ways to fabricate self-healing polymers with high mechanical strength. The mechanical properties of the resultant polymers are certainly affected by the size of separated phase domain. However, the study on this aspect is absence, because it can hardly exclude the influence of variation in monomer proportion required for tuning the separated phase size. Here, we report the first study on tuning the phase size through reversible addition-fragmentation chain transfer (RAFT) polymerization without changing the proportion of monomers. As expected, the size of separated phase has been successfully mediated from 15 nm to 9 nm by tuning the molecular weight of the chain transfer agent. It is found that the mechanical strength and the self-healing efficiency of the resultant polymers increase simultaneously with the decrease of phase size. The study on the formation kinetics of hydrogen bonds reveals that the decrease of phase size can facilitate the re-bonding rate of hydrogen bonds, even if the migration of polymer chains is restricted. [ABSTRACT FROM AUTHOR]

Designing materials capable of adapting their mechanical properties in response to external stimuli is the key to preventing failure and extending their service life. However, existing mechanically adaptive polymers are hindered by limitations such as inadequate load‐bearing capacity, difficulty in achieving reversible changes, high cost, and a lack of multiple responsiveness. Herein, we address these challenges using dynamic coordination bonds. A new type of mechanically adaptive material with both rate‐ and temperature‐responsiveness was developed. Owing to the stimuli‐responsiveness of the coordination equilibria, the prepared polymers, PBMBD‐Fe and PBMBD‐Co, exhibit mechanically adaptive properties, including temperature‐sensitive strength modulation and rate‐dependent impact hardening. Benefitting from the dynamic nature of the coordination bonds, the polymers exhibited impressive energy dissipation, damping capacity (loss factors of 1.15 and 2.09 at 1.0 Hz), self‐healing, and 3D printing abilities, offering durable and customizable impact resistance and protective performance. The development of impact‐resistant materials with comprehensive properties has potential applications in the sustainable and intelligent protection fields. [ABSTRACT FROM AUTHOR]

Self‐healing polymeric materials, which can repair physical damage, offer promising prospects for protective applications across various industries. Although prolonged durability and resource conservation are key advantages, focusing solely on mechanical recovery may limit the market potential of these materials. The unique physical properties of self‐healing polymers, such as interfacial reduction, seamless connection lines, temperature/pressure responses, and phase transitions, enable a multitude of innovative applications. In this perspective, the diverse applications of self‐healing polymers beyond their traditional mechanical strength are emphasized and their potential in various sectors such as food packaging, damage‐reporting, radiation shielding, acoustic conservation, biomedical monitoring, and tissue regeneration is explored. With regards to the commercialization challenges, including scalability, robustness, and performance degradation under extreme conditions, strategies to overcome these limitations and promote successful industrialization are discussed. Furthermore, the potential impacts of self‐healing materials on future research directions, encompassing environmental sustainability, advanced computational techniques, integration with emerging technologies, and tailoring materials for specific applications are examined. This perspective aims to inspire interdisciplinary approaches and foster the adoption of self‐healing materials in various real‐life settings, ultimately contributing to the development of next‐generation materials. [ABSTRACT FROM AUTHOR]

Self-healing polymer networks have attracted much attention because of the contribution to resource and energy savings by improving their service life. Herein, photo-polymerization reactions of α-cyclodextrin-glycidyl methacrylate adduct (αCD-GMA)/poly(ethylene glycol) methacrylate (PEGMA), β-cyclodextrin-glycidyl methacrylate adduct (βCD-GMA)/PEGMA, and αCD-GMA/3,4-dichlorophenyl isocyanate-end-capped PEGMA produced cyclodextrin/poly(ethylene glycol)-based network (CP, βCP, and DCP-CP, respectively) films. The thermal, mechanical, and self-healing properties of the CP films were compared with those of the βCP and DCP-CP films. The loss factor (tan δ) peak temperatures (− 9 to − 3 °C) measured via dynamic mechanical analysis (DMA), tensile strengths and moduli of the CP films decreased with increasing PEGMA content. Although all photo-polymerized films exhibited self-healing properties upon standing at room temperature for 24 h, the healing efficiencies in terms of tensile strength for the CP films were much higher than those for the βCP and DCP-CP films, in which the complexation of cyclodextrin-poly(ethylene glycol) (PEG) units is difficult. The CP film with the highest PEGMA fraction exhibited the highest healing efficiency and healed at least thrice. The 2D 1H–1H NOESY spectra of αCD-GMA/PEGMA and immersion of the self-healed CP film in PEG solutions suggested that the self-healing properties were imparted by reversible α-CD–PEG host–guest interactions. [ABSTRACT FROM AUTHOR]

Polymeric materials used for the polymer bonded explosive (PBX) or other energetic composite materials (ECMs) that simultaneously possess excellent mechanical properties and high self-healing ability, convenient healing, and facile fabrication are always a huge challenge. Herein, self-healing linear polyurethane elastomers (PTMEG2000-IPDI-DAPU, denoted as 2I-DAPU) with high healing efficiency and mechanical properties were facilely fabricated by constructing reversible covalent bonds and dynamic hard domains into polymer chains. Furthermore, a TATB-based PBX using as-prepared 2I-DAPU polymer as the binder was constructed, disclosing an excellent self-healing property to heal cracks generated during fabrication, transportation and storage. The damage healing manner of such a PBX sample was investigated by means of prefabricated damage through mechanical load, heal treatment via heating at high temperature, and CT-scanning the inner structure and mechanical property characterization via Brazilian test. The self-healing mechanism of internal damage in PBX was preliminarily explored. We propose that this 2I-DAPU binder with Diels-Alder bonds could generate plentiful active surface groups resulting from damage and drive self-healing at fitting temperature and increase the slightly packed hard phase via incorporating a small amount of hydrogen bonds. This work may offer a novel strategy for improving mechanical property and healing ability in the field of self-healing material which could help expand its applications with enhanced versatility in mechanical-enhanced functional materials.

This study explores the synthesis and evaluation of UV-curable urethane (meth)acrylates (UA) incorporating a Diels–Alder adduct (HODA), diisocyanate, poly(ethylene glycol), and hydroxy (meth)acrylate. Six UAs, distinguished by the soft segment of polymer chains, underwent comprehensive characterization using FTIR and NMR spectroscopy. Real-time monitoring of the UV-curing process and analysis of self-healing properties were performed. The research investigates the influence of various molecular weights of PEGs on the self-healing process, revealing dependencies on photopolymerization kinetics, microstructure, thermal properties, and thermoreversibility of urethane (meth)acrylates. This work provides valuable insights into the development of UV-curable coatings with tailored properties for potential applications in advanced materials. [ABSTRACT FROM AUTHOR]

One of the main challenges of space exploration is to properly protect astronauts from the hazards of the space environment. Space suits were hence created to protect crewmembers during extravehicular activities, but they are currently unable to properly withstand damage after, for example, impacts with micrometeoroids and orbital debris (MMOD), and they would depressurize and collapse if punctured, with catastrophic consequences. In this context, the possibility of integrating self-healing materials into spacesuits has drawn the attention of the scientific community, as it would lead to autonomous damage restoration and subsequently increased safety and operational life. Nevertheless, the effects of space environment on these materials are still to be determined and could lead to a significant decrease of their overall performance. The here presented study focuses on a first example of application to a space suit, analyzing the healing performance of a set of candidate self-healing polymers before and after exposure to simulated space radiation. A comparison of bilayers and nanocomposites having these polymers as matrices is also made in the non-irradiated case. This research also aims at filling the gap between standard characterization of self-healing materials (e.g.: scratch, impact, and puncture tests) and assessment of the effects of space radiation on them by combining these two aspects. Understanding if and how radiation can affect damage recovery performance is in fact fundamental to determine whether a given self-healing material can actually be used for space applications. The self-healing response is assessed through in-situ flow rate measurements after puncture damage. Maximum and minimum flow rate, the time between them and the air volume lost within the 3 min following puncture are collected as healing performance parameters. For the neat materials, the same tests are then repeated on gamma-ray irradiated samples to study the variation in self-repairing performance after exposure to simulated space radiation. Results show that the healing performance is higher in systems with lower viscous response and that it decreases after irradiation. A further analysis of the effects of space environment on the presented materials is hence required. The NASA HZETRN2015 (High Z and Energy TRaNsport, 2015 version) software is also used to simulate the action of galactic cosmic rays on the space suit during extravehicular activity. The classic suit multilayer is compared with configurations in which the standard bladder is replaced with a layer of each analyzed material to identify the most promising candidates and determine whether the addition of nanofillers significantly increases the shielding ability. • Safer, long-lasting space structures thanks to self-healing polymers. • New relevant information obtained on radiation effects on self-healing polymers. • Promising self-healing performance of poly (urea) urethanes. • Suit shielding performance not compromised by the proposed self-healing polymers. [ABSTRACT FROM AUTHOR]

The goal of this paper was to establish a metric, which we refer to as the resilience parameter, to evaluate the ability of a material to retain tensile strength after damage recovery for shape memory polymer (SMP) systems. In this work, three SMP blends created for the additive manufacturing process of fused filament fabrication (FFF) were characterized. The three polymer systems examined in this study were 50/50 by weight binary blends of the following constituents: (1) polylactic acid (PLA) and maleated styrene-ethylene-butylene-styrene (SEBS-g-MA); (2) acrylonitrile butadiene styrene (ABS) and SEBS-g-MA); and (3) PLA and thermoplastic polyurethane (TPU). The blends were melt compounded and specimens were fabricated by way of FFF and injection molding (IM). The effect of shape memory recovery from varying amounts of initial tensile deformation on the mechanical properties of each blend, in both additively manufactured and injection molded forms, was characterized in terms of the change in tensile strength vs. the amount of deformation the specimens recovered from. The findings of this research indicated a sensitivity to manufacturing method for the PLA/TPU blend, which showed an increase in strength with increasing deformation recovery for the injection molded samples, which indicates this blend had excellent resilience. The ABS/SEBS blend showed no change in strength with the amount of deformation recovery, indicating that this blend had good resilience. The PLA/SEBS showed a decrease in strength with an increasing amount of initial deformation, indicating that this blend had poor resilience. The premise behind the development of this parameter is to promote and aid the notion that increased use of shape memory and self-healing polymers could be a strategy for mitigating plastic waste in the environment. [ABSTRACT FROM AUTHOR]

Self‐healing is a natural characteristic observed in organisms capable of repairing themselves following mechanical damage. Inspired by this attractive feature, researchers have developed self‐healing polymers with various functionalities to create advanced self‐healing devices that offer substantially enhanced durability and longevity. This paper provides an overview of self‐healing polymers and their assessment methods, followed by the design strategy for electrically functional self‐healing polymers, with a particular focus on the latest research findings. Finally, the paper discusses future prospects and challenges in this field. [ABSTRACT FROM AUTHOR]

Despite being primarily categorized as non-autonomous self-healing polymers, we demonstrate the ability of Diels–Alder polymers to heal macroscopic damages at room temperature, resulting in complete restoration of their mechanical properties within a few hours. Moreover, we observe immediate partial recovery, occurring mere minutes after reuniting the fractured surfaces. This fast room-temperature healing is accomplished by employing an off-stoichiometric maleimide-to-furan ratio in the polymer network. Through an extensive investigation of seven Diels–Alder polymers, the influence of crosslink density on self-healing, thermal, and (thermo-)mechanical performance was thoroughly examined. Crosslink density variations were achieved by adjusting the molecular weight of the monomers or utilizing the off-stoichiometric maleimide-to-furan ratio. Quasistatic tensile testing, dynamic mechanical analysis, dynamic rheometry, differential scanning calorimetry, and thermogravimetric analysis were employed to evaluate the individual effects of these parameters on material performance. While lowering the crosslink density in the polymer network via decreasing the off-stoichiometric ratio demonstrated the greatest acceleration of healing, it also led to a slight decrease in (dynamic) mechanical performance. On the other hand, reducing crosslink density using longer monomers resulted in faster healing, albeit to a lesser extent, while maintaining the (dynamic) mechanical performance. [ABSTRACT FROM AUTHOR]

The development of new photoreactive resins to obtain smart coatings and enhance the self‐healing (SH) properties of photoreactive resins has attracted great interest in the past few years, and the investigation of the relationship between phase structure and smart properties is necessary. Herein, four types of urethane acrylate resins with built‐in DA structures with different hard segment structures, and a slight change in the length of the polyol soft segment were prepared. The hard segments were made of hexamethylene diisocyanate (HDI) with a linear structure and isophorone diisocyanate (IPDI) with an alicyclic structure, and the soft segments consisted of polyethylene glycols (PEG 400 and PEG 1000, respectively). The obtained resins were used to prepare polymer films that were cured using UV radiation. The coatings obtained in this way were tested for the influence of the polymer chain architecture on the kinetics of photopolymerization, the properties of the cured coatings, as well as the thermal characteristics and thermoreversibility performance of the cured coatings and their SH ability. [ABSTRACT FROM AUTHOR]

Physically crosslinked hydrogels consisting of polyacrylamide (Aam) and polyoctadecylacrylate (C18A) blocks, leading to hydrophilic and hydrophobic domains respectively, are prepared by micellar polymerization. A multifunctional monomer (divinylbenzene, DVB), is also employed to create branched chains. The effect of the polymer composition and the amount of the branching agent on the material characteristics are evaluated. The melting enthalpies of the hydrophobic domains increase as the n‐octadecyl acrylate unit amount increases and, in a parallel fashion, an increase in the mechanical modulus G' of the hydrogel is observed. Furthermore, G′ increases as the DVB concentration increases. Self‐healing behavior is also demonstrated both visually and by rheological measurements. Finally, once heated above the melting temperature (Tm), these hydrogels can be deformed into different shapes that can be fixed on cooling. Then, heating again above Tm, the original shape is recovered thus indicating shape memory characteristics. [ABSTRACT FROM AUTHOR]

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A series of UV-curable urethane (meth)acrylates were obtained by copolymerization of the Diels–Alder adduct (HODA), isophorone diisocyanate, PEG1000, and various hydroxy (meth)acrylates. The aim of the present work was to determine the influence of the chemical structure of the introduced (meth)acrylic groups, i.e., hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate, on the UV-curing process and self-healing properties of cured coatings. The chemical structure of prepolymers was characterized by FTIR and NMR spectroscopy, whereas the UV-curing process was monitored in real time using FTIR and photo-DSC. In turn, the self-healing properties were characterized in relation to the thermally reversible mechanism, which was tested using the following methods: an FTIR spectroscope equipped with a heating attachment; DSC and TG apparatus; and an optical microscope equipped with a stage with programmable heating. The result of comprehensive research on the self-healing of photocurable coatings in the context of the presence of various photoreactive groups and the course of the curing process allows one to control the self-healing process by reducing the effective healing temperature. The self-healing properties, taken together with the fast UV curing of the coatings and excellent properties of cured coatings, make the material attractive for a variety of applications, in particular in cases where coatings are not repaired, e.g., for economic reasons or when it is not possible, such as in flexible electronic screens, car paint film, and aircraft interior finishes. [ABSTRACT FROM AUTHOR]

In the field of soft robotics, knowledge of material science is becoming more and more important. However, many researchers have a background in only one of both domains. To aid the understanding of the other domain, this tutorial describes the complete process from polymer synthesis over fabrication to testing of a soft finger. Enough background is provided during the tutorial such that researchers from both fields can understand and sharpen their knowledge. Self-healing polymers are used in this tutorial, showing that these polymers that were once a specialty, have become accessible for broader use. The use of self-healing polymers allows soft robots to recover from fatal damage, as shown in this tutorial, which increases their lifespan significantly. [ABSTRACT FROM AUTHOR]

This review is devoted to the description of methods for the self-healing of polymers, polymer composites, and coatings. The self-healing of damages that occur during the operation of the corresponding structures makes it possible to extend the service life of the latter, and in this case, the problem of saving non-renewable resources is simultaneously solved. Two strategies are considered: (a) creating reversible crosslinks in the thermoplastic and (b) introducing a healing agent into cracks. Bond exchange reactions in network polymers (a) proceed as a dissociative process, in which crosslinks are split into their constituent reactive fragments with subsequent regeneration, or as an associative process, the limiting stage of which is the interaction of the reactive end group and the crosslink. The latter process is implemented in vitrimers. Strategy (b) is associated with the use of containers (hollow glass fibers, capsules, microvessels) that burst under the action of a crack. Particular attention is paid to self-healing processes in metallopolymer systems. [ABSTRACT FROM AUTHOR]

Paper used for packaging applications is often coated with thin polymer coatings to improve the properties, like printability and barrier properties, respectively. Today, these coatings are still often based on petroleum-based polymers. In this study, the fabrication of biobased thin film coatings is described. Poly(itaconic acid ester)s, which are prepared by emulsion polymerization, are used as water-based coatings for paper. The thermal properties of the polymers are tuned by the side chain of the monomers (diethyl itaconate vs. dibutyl itaconate). Different formulations based on the polymer emulsion and additives, like rheology modifiers, are prepared and their film formation is studied. The usage of a rheology modifier results in excellent film formation. These polymer coatings feature an additional function - they are capable of self-healing. The healing ability is studied in scratch healing tests, in which almost complete recovery can be observed after healing at 100 °C. Moreover, the restoration of optical properties/aesthetics is studied. In gloss measurements before and after damage as well as after a healing time the complete recovery of the gloss can be observed. Furthermore, the barrier properties against fat are studied., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Mixtures of tung oil (TO) and 4,4'-bismaleimidodiphenylmethane (BMI) in the molar ratios of 1:3 and 2:3 were cured at 100 °C or 160 °C to produce the cured products (TB13, TB23 or htTB13, htTB23). Fourier-transform infrared spectroscopy of the cured products confirmed that the trans, trans-diene moieties of TO are almost completely consumed for all the cured products; furthermore, the maleimide groups were almost completely consumed for all the cured products, except for TB13. Differential scanning calorimetry results of the cured products revealed that TB13 and TB23 exhibited strong endothermic peaks due to the retro-Diels–Alder (rDA) reaction. The rDA enthalpy change (ΔHrDA) of TB13 was higher than that of TB23, and the ΔHrDAs of htTB13 and htTB23 were considerably smaller than that of TB13 and TB23. The tan δ peak temperatures of the cured products measured by dynamic mechanical analysis were in the range of 55–131 °C and were increased in the order: TB23 < TB13 < htTB23 < htTB13. The 5% weight loss temperatures of all the cured products were higher than 400 °C. Although TB13 and TB23 exhibited self-healing properties upon hot-pressing at 100 and 120 °C, respectively, htTB13 and htTB23 exhibited no self-healing ability. [ABSTRACT FROM AUTHOR]

The aim to achieve sustainable development goals (SDG) and cut CO2-emission is forcing researchers to develop bio-based materials over conventional polymers. Since most of the established bio-based polymeric materials demonstrate prominent sustainability, however, performance, cost, and durability limit their utilization in real-time applications. Additionally, a sustainable circular bioeconomy (CE) ensures SDGs deliver material production, where it ceases the linear approach from production to waste. Simultaneously, sustainable circular bio-economy promoted materials should exhibit the prominent properties to involve and substitute conventional materials. These interceptions can be resolved through state-of-the-art bio-vitrimeric materials that display durability/mechanical properties such as thermosets and processability/malleability such as thermoplastics. This article emphasizes the current need for vitrimers based on bio-derived chemicals; as well as to summarize the developed bio-based vitrimers (including reprocessing, recycling and self-healing properties) and their requirements for a sustainable circular economy in future prospects. [ABSTRACT FROM AUTHOR]

The search for materials with better performance, longer service life, lower environmental impact, and lower overall cost is at the forefront of polymer science and material engineering. This has led to the development of self‐healing polymers with a range of healing mechanisms including capsular‐based, vascular, and intrinsic self‐healing polymers. The development of self‐healable systems has been inspired by the healing of biological systems such as skin wound healing and broken bone reconstruction. The goal of using self‐healing polymers in various applications is to extend the service life of polymers without the need for replacement or human intervention especially in restricted access areas such as underwater/underground piping where inspection, intervention, and maintenance are very difficult. Through an industrial and scholarly lens, this paper provides: a) an overview of self‐healing polymers; b) classification of different self‐healing polymers and polymer‐based composites; c) mechanical, thermal, and electrical analysis characterization; d) applications in coating, composites, and electronics; e) modeling and simulation; and f) recent development in the past 20 years. This review highlights the importance of healable polymers for an economically and environmentally sustainable future, the most recent advances in the field, and current limitations in fabrication, manufacturing, and performance. [ABSTRACT FROM AUTHOR]

Self-healing polymers such as poly(ethylene-co-methacrylic acid) ionomers (PEMAA) can heal themselves immediately after a projectile puncture which in turn lowers environmental pollution from replacement. In this study, the thermal-mechanical properties and self-healing response of a library of 15 PEMAA copolymers were studied to understand the effects of the ionic content (Li, Na, Zn, Mg) and neutralization percentage (13 to 78%) on the results. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile testing were used to study the thermo-mechanical properties of PEMAA copolymers while the self-healing response was studied using the projectile test. Puncture sites were observed using scanning electron microscopy (SEM) and the healing efficiency was quantitatively measured using the water leakage test. Five different self-healing responses were observed and correlated to ionic content and neutralization. At high neutralization, divalent neutralizing ions (Zn and Mg) that have stronger ionic interactions exhibited brittle responses during projectile testing. PEMAA samples neutralized with Mg and Li at low concentrations had a higher healing efficiency than PEMAA samples neutralized with Zn and Na at low neutralization. The PEMAA copolymers with higher tensile stress and two distinct peaks in the graph of loss factor versus temperature that indicate the presence of sufficient ionic aggregate clusters had improved healing efficiency. By increasing the neutralization percentage from 20% to 70%, the tensile strength and modulus of the samples increased and their self-healability generally increased. Among the investigated samples, the copolymer with ~50% neutralization by Li salt showed the highest healing efficiency (100%). Overall, the strength and elastic response required for successful self-healing responses in PEMAA copolymers are shown to be governed by the choice of ion and the amount of neutralization. [ABSTRACT FROM AUTHOR]

The self-healing behavior of two supramolecular polymers based on π–π-interactions featuring different polymer backbones is presented. For this purpose, these polymers were synthesized utilizing a polycondensation of a perylene tetracarboxylic dianhydride with polyether-based diamines and the resulting materials were investigated using various analytical techniques. Thus, the molecular structure of the polymers could be correlated with the ability for self-healing. Moreover, the mechanical behavior was studied using rheology. The activation of the supramolecular interactions results in a breaking of these noncovalent bonds, which was investigated using IR spectroscopy, leading to a sufficient increase in mobility and, finally, a healing of the mechanical damage. This scratch-healing behavior was also quantified in detail using an indenter.

We have developed new types of thermosets from bio-based benzoxazine/epoxy copolymers with shape memory and self-healing properties that could be triggered by using near-infrared (NIR) light, without using any filler. The copolymers were prepared from bio-based raw materials, including vanillin, furfurylamine, and epoxidized castor oil, along with functionalized with glutaric anhydride (GA), due to which self-healing properties of the copolymers were enabled through dynamic covalent bonds. Effects of GA content (0.00, 0.02, 0.04, 0.06, 0.08, and 0.10 mol) on molecular structure, mechanical properties, dynamic mechanical properties, and thermal stability of the copolymers were investigated. The results from infrared spectroscopy showed the formation of ester linkages and free carboxylic acids upon functionalization of copolymers with GA. The increased crosslinking density by GA was observed from increased tensile strength (from 11 to 16 MPa), glass transition temperature (72–150 °C), and degradation temperature at 5% weight loss (382–405 °C) of the copolymers. However, excess contents (0.08 and 0.10 mol) of GA might result in the existence of free components, hindering the formation of the copolymer network and diminishing the mechanical properties of the copolymers. Shape memory properties of GA-functionalized V-fa/ECO copolymers were investigated under NIR actuation; the results showed a 100% of shape recovery ratio within 20 s of actuation. Self-healing properties of GA-functionalized V-fa/ECO copolymers were investigated under NIR actuation; the results showed 94% of restored storage modulus after 20 min of actuation. Lastly, the self-healing mechanism under NIR actuation was proposed that NIR photothermal effects of the copolymers induced the crack closing due to their shape memory effects. Consequently, the copolymer chains could diffuse across the crack interface along with transesterification through GA functionalities, leading to crack healing. The findings of this study suggested a new way to produce NIR light-responsive self-healing polymer without using NIR photothermal filler.

Self-healing polymeric materials are intelligent materials engineered to autonomously repair damages using external stimuli which are the vanguard of sustainable materials research. The ability to maintain product quality and functionality, extended lifespan of products and cost-effectiveness play a significant role for the development of self-healing polymers (SHPs) and all of which substantially reduce the environmental impact of plastic waste. Over the years, Reversible Deactivation Radical Polymerization (RDRP) techniques, such as Nitroxide-mediated radical polymerization (NMP), Atom Transfer Radical Polymerization (ATRP), Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization and Ring-Opening Metathesis Polymerization (ROMP) have been widely used to synthesize SHPs with precise control over the molecular weight, distribution, architecture and functionality. Despite their potential, there is no comprehensive review that addresses the synthesis, advantages and applications of SHPs via RDRP methods. This review fills that gap by presenting detailed case studies that elucidate the unique properties and applications of SHPs synthesized through RDRP methods. The primary goal of this review is to provide a comprehensive perspective on the design of SHPs using various RDRP techniques, highlighting how these methods enable the preparation of SHPs with controlled architectures. Case studies of various RDRP techniques like ATRP, RAFT, NMP and ROMP are described, exhibiting their application in different healing mechanisms, such as reversible Diels-Alder (DA) and retro-DA (rDA) reactions, π-π interactions, hydrogen bonding and encapsulated microcapsules. By bridging the gap between fundamental RDRP techniques and practical applications of SHPs, this review aims to guide researchers and industry professionals in developing next-generation materials with enhanced self-healing capabilities. [Display omitted] [ABSTRACT FROM AUTHOR]

Lignin, a biopolymer derived from plant biomass, is recognized as a highly promising substance for developing self-healing polymers owing to its dynamic linkages and functional groups. This paper provides a thorough review of lignin-based self-healing polymer, from the process of extracting lignin, chemical modification, synthesis techniques such as via reversible addition-fragmentation chain transfer (RAFT) polymerization, crosslinking with polymers like polyvinyl alcohol (PVA) and chitosan, and reactions with isocyanates to create lignin-based networks with reversible interactions. This work also summarizes the optimization of self-healing ability, such as including dynamic copolymers, encapsulating healing agents like dicyclopentadiene and polycaprolactone (PCL), and chain extenders with disulfide or Diels-Alder (DA) moieties. The material's characterization focuses on its capacity to recover via hydrogen bonding and dynamic re-associations, improved mechanical properties from lignin's rigid structure, and enhanced temperature resistance. Primary obstacles involve the optimization of lignin extraction, enhancement of polymer compatibility, and the establishment of efficient procedures for synthesis and characterization. Overall, lignin shows great potential as a renewable component of self-healing polymers, with plenty of opportunities for further development. • Lignin in self-healing polymers utilizes its aromatic nature and diverse functional groups • Adding reactive groups to lignin's backbone is a popular method in self-healing synthesis • Lignin and its derivatives' hydrogen bond are key to its self-healing ability • Optimizing self-healing polymers with copolymer, healing agents, or extenders is crucial • Lignin's UV absorption and antibacterial properties enhance polymer performance [ABSTRACT FROM AUTHOR]

The fields of polymer science, conductive composites, materials engineering, robotics, and human perception intersect at the development and application of synthetic human skin. To be accepted by human users, artificial human skin must meet several requirement benchmarks. Synthetic human skin must look realistic, but not be eerie or creepy, upsetting those using or interacting with the material. Synthetic skin must feel like human skin, including mechanical response, thermal conductivity, and tactile properties. Realistic synthetic human skin must be electrically conductive, so that the user may experience accurate sensations of touch and feel. Finally, synthetic human skin should possess some degree of self-healing behavior. This review provides a brief description of advances in these disparate aspects of synthetic skin science, from the perspective of a practicing conductive polymer composite scientist and engineer. [ABSTRACT FROM AUTHOR]

Conductive polymer composites can be customized through the addition of conductive fillers to the matrix. Fillers added to a conductive polymer composite modify the mechanical properties of the material as well as the electrical properties. Previous work with conductive polymer composites determined that conductive polymers with carbon‐based materials exhibit more brittle behavior when compared with unmodified polymers, reducing strains to failure of the material. A conductive polymer with self‐healing functionality could be healed to repair damage. This work demonstrates a conductive polyethylene composite, which can simultaneously restore electrical and mechanical performance when heated with induction. Because carbon‐based conductive composites cannot be sufficiently heated for healing, aluminum flake added to the composite served as the susceptor for induction heating. Conductive polyethylene specimens with 20% aluminum flake by volume demonstrated similar mechanical behavior both during the initial test and after healing. [ABSTRACT FROM AUTHOR]

Polymer composites are becoming an important class of materials for a diversified range of industrial applications due to their unique characteristics and natural and synthetic reinforcements. Traditional methods of polymer composite fabrication require machining, manual labor, and increased costs. Therefore, 3D printing technologies have come to the forefront of scientific, industrial, and public attention for customized manufacturing of composite parts having a high degree of control over design, processing parameters, and time. However, poor interfacial adhesion between 3D printed layers can lead to material failure, and therefore, researchers are trying to improve material functionality and extend material lifetime with the addition of reinforcements and self-healing capability. This review provides insights on different materials used for 3D printing of polymer composites to enhance mechanical properties and improve service life of polymer materials. Moreover, 3D printing of flexible energy-storage devices (FESD), including batteries, supercapacitors, and soft robotics using soft materials (polymers), is discussed as well as the application of 3D printing as a platform for bioengineering and earth science applications by using a variety of polymer materials, all of which have great potential for improving future conditions for humanity and planet Earth. [ABSTRACT FROM AUTHOR]

Abstract Although dipolar forces between copolymer chains are relatively weak, they result in ubiquitous inter‐ and/or intramolecular interactions which are particularly critical in achieving the mechanical integrity of polymeric materials. In this study, a route is developed to obtain self‐healable properties in thermoplastic copolymers that rely on noncovalent dipolar interactions present in essentially all macromolecules and particularly fluorine‐containing copolymers. The combination of dipolar interactions between C─F and C═O bonds as well as CH2/CH3 entities facilitates self‐healing without external intervention. The presence of dipole‐dipole, dipole‐induced dipole, and induced‐dipole induced dipole interactions leads to a viscoelastic response that controls macroscopic autonomous multicycle self‐healing of fluorinated copolymers under ambient conditions. Energetically favorable dipolar forces attributed to monomer sequence and monomer molar ratios induces desirable copolymer tacticities, enabling entropic energy recovery stored during mechanical damage. The use of dipolar forces instead of chemical or physical modifications not only eliminates additional alternations enabling multiple damage‐repair cycles but also provides further opportunity for designing self‐healable commodity thermoplastics. These materials may offer numerous applications, ranging from the use in electronics, ion batteries, H2 fuel dispense hoses to self‐healable pet toys, packaging, paints and coatings, and many others.

A novel thermally mendable polyurethane binder for energetic composites was designed and prepared via the Diels‐Alder (DA) cycloaddition reaction between a furan functionalized polycaprolactone (PCL) prepolymer and a bismaleimide compound. The structures and properties of synthesized PCL‐DA‐PU were fully characterized via Proton Nuclear Magnetic Resonance (1H‐NMR) and Fourier Transform Infrared spectroscopy (FT‐IR), Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC) measurements. As‐prepared material showed good self‐healing ability of scratches by virtue of combining the shape recovery effect of PCL segments favoring scratch closure with the re‐crosslinking of the cleaved DA bonds, which was evidenced by optical microscopy and tensile analysis. A scratch healing efficiency determined by tensile tests of about 89% was achieved. Moreover, with the contribution of DA bonds in PCL‐DA‐PU binder, the microcracks and other damages in the TATB based energetic composites were almost mended and the mechanical strength can recovery above 78%. [ABSTRACT FROM AUTHOR]

Although dipolar forces between copolymer chains are relatively weak, they result in ubiquitous inter‐ and/or intramolecular interactions which are particularly critical in achieving the mechanical integrity of polymeric materials. In this study, a route is developed to obtain self‐healable properties in thermoplastic copolymers that rely on noncovalent dipolar interactions present in essentially all macromolecules and particularly fluorine‐containing copolymers. The combination of dipolar interactions between C─F and C═O bonds as well as CH2/CH3 entities facilitates self‐healing without external intervention. The presence of dipole‐dipole, dipole‐induced dipole, and induced‐dipole induced dipole interactions leads to a viscoelastic response that controls macroscopic autonomous multicycle self‐healing of fluorinated copolymers under ambient conditions. Energetically favorable dipolar forces attributed to monomer sequence and monomer molar ratios induces desirable copolymer tacticities, enabling entropic energy recovery stored during mechanical damage. The use of dipolar forces instead of chemical or physical modifications not only eliminates additional alternations enabling multiple damage‐repair cycles but also provides further opportunity for designing self‐healable commodity thermoplastics. These materials may offer numerous applications, ranging from the use in electronics, ion batteries, H2 fuel dispense hoses to self‐healable pet toys, packaging, paints and coatings, and many others. [ABSTRACT FROM AUTHOR]

The scratch healing behavior of different polymers based on reversible interactions was investigated. For this purpose, scratches were induced via femtosecond laser ablation and were analyzed using laser-scanning microscopy. The healing process was monitored over time and the residual scratch volume was studied. Thus, healing kinetics of different self-healing polymers were obtained revealing a new three step-healing process. An initial time is required in order to start the crack closure behavior. Afterwards, a fast healing behavior followed by a final slow healing period could be observed. Consequently, this study discloses significant insights into the time-dependent healing behavior of polymeric materials.

With the recent emphasis on environmental protection measures, there are increasingly strong demands for environment‐friendly multifunctional materials, so research regarding high‐performance, recyclable, functional materials with self‐healing abilities is of great interest. However, the comprehensive mechanical properties of most available self‐healing materials are insufficient; to date, most developed materials are either tough but brittle or flexible but weak. This report describes the application of a crosslinking strategy based on multiple dynamic bonds for the development of an autonomically self‐healing, multifunctional, boroxine‐containing poly(dimethylsiloxane) elastomer (PDMS‐BN). This approach takes advantage of well‐designed intermolecular and intramolecular nitrogen‐coordinated boroxines by using a synergetic dynamic mechanism. The elastomers exhibit enhanced comprehensive mechanical properties (with maximum strength up to 1.72 MPa, elongation at break up to 307%, Young's modulus up to 11.18 ± 0.52 MPa, and toughness up to 4.92 MJ m−3) and highly autonomic self‐healing capabilities, with ≈96% efficiency at room temperature for 48 h. Moreover, the PDMS‐BN elastomer can be recycled multiple times via crushing/molding or disassembling/casting processes, without losing their original mechanical robustness. The as‐prepared elastomers also demonstrate good adhesive properties and a unique fluorescence‐quenching response in the presence of Fe3+ ions. [ABSTRACT FROM AUTHOR]

Thermoplastic polyurethane (TPU) is a melt‐processing polymer with a high elasticity, high tensile strength, low‐temperature resistance, wear‐resistance, and corrosion resistance ability. TPU can be used in the automotive industry, electronics, medical supplies, coatings, and sports equipment. Introduction of self‐healing performance has made a considerable contribution to the service life and recyclability of TPU. The present article analyzes recent progress in self‐healing supramolecular TPUs. In particular, the importance of self‐healing mechanisms governed by covalent bonds and non‐covalent interactions in polymer design that allows for balancing mechanical performance and repairability is summarized. The critical issues and challenges associated with self‐healing supramolecular TPUs are also discussed. [ABSTRACT FROM AUTHOR]

A new method was provided to synthesize Diels–Alder (DA) self-healing cross-linked polyamides (SH-cPAs) with high tensile strength and good self-healing efficiency. A furfurylamine-N,N'-bis(methyl propionate) (FA-BMP) was synthesized through the Michael addition of furfurylamine and methyl acrylate. Bulk polycondensation of FA-BMP with bis(2-aminopropyl) polypropylene glycol and m-xylylenediamine were conducted, and several polyamide prepolymers containing furan pendent groups (pFU-PAs) were synthesized. From a DA reaction between pFU-PAs and 1,5-bismaleimido-2-methylpentane, different SH-cPAs were prepared. The pFU-PAs were characterized by 1H NMR, 13C NMR, FT-IR, amine values, and size exclusion chromatography. The DA reaction in SH-cPAs were demonstrated by FT-IR and 1H NMR spectra. Their thermally repairing was verified with polarizing optical microscopy and tensile tests. SH-cPAs exhibits tensile strength up to 37 MPa with strain at break of 27%-164%. Their tensile strength after self-repairing was still up to 26 MPa with self-healing efficiency of 70%-92%. [ABSTRACT FROM AUTHOR]