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The current research studies the synergistic effect of Cydonia oblonga and its extracted nano bio‑silver as a natural and eco-friendly agent for the improvement of three-dimensional (3D)-printed alginate wound dressings. Therefore, Cydonia oblonga extract was first prepared and silver nanoparticles were extracted from it through a green and simple method. The Cydonia oblonga and its extracted bio-based nanoparticles were then added to 3D printing alginate-based ink. Subsequently, a 3D structural extrusion printer was employed to create the porous hydrogel-based wound dressings. The morphological investigation demonstrated that using the extraction method the bio-based silver nanoparticles were successfully prepared, having an average size of 17.95 ± 4.50 nm. The Cydonia oblonga extract showed comparable antioxidant activity to the commercial antioxidant and an excellent total phenol content. In addition, the results showed the combination of Cydonia oblonga extracts/silver nanoparticles significantly improved the antibacterial performance of alginate-based bioinks. In vivo, and in vitro studies confirmed their biocompatibility and significant efficacy in the treatment of burn wounds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Despite critical advances in regenerative medicine, the generation of definitive, reliable treatments for musculoskeletal diseases remains challenging. Gene therapy based on the delivery of therapeutic genetic sequences has strong value to offer effective, durable options to decisively manage such disorders. Furthermore, scaffold-mediated gene therapy provides powerful alternatives to overcome hurdles associated with classical gene therapy, allowing for the spatiotemporal delivery of candidate genes to sites of injury. Among the many scaffolds for musculoskeletal research, hydrogels raised increasing attention in addition to other potent systems (solid, hybrid scaffolds) due to their versatility and competence as drug and cell carriers in tissue engineering and wound dressing. Attractive functionalities of hydrogels for musculoskeletal therapy include their injectability, stimuli-responsiveness, self-healing, and nanocomposition that may further allow to upgrade of them as "intelligently" efficient and mechanically strong platforms, rather than as just inert vehicles. Such functionalized hydrogels may also be tuned to successfully transfer therapeutic genes in a minimally invasive manner in order to protect their cargos and allow for their long-term effects. In light of such features, this review focuses on functionalized hydrogels and demonstrates their competence for the treatment of musculoskeletal disorders using gene therapy procedures, from gene therapy principles to hydrogel functionalization methods and applications of hydrogel-mediated gene therapy for musculoskeletal disorders, while remaining challenges are being discussed in the perspective of translation in patients. STATEMENT OF SIGNIFICANCE: Despite advances in regenerative medicine, the generation of definitive, reliable treatments for musculoskeletal diseases remains challenging. Gene therapy has strong value in offering effective, durable options to decisively manage such disorders. Scaffold-mediated gene therapy provides powerful alternatives to overcome hurdles associated with classical gene therapy. Among many scaffolds for musculoskeletal research, hydrogels raised increasing attention. Functionalities including injectability, stimuli-responsiveness, and self-healing, tune them as "intelligently" efficient and mechanically strong platforms, rather than as just inert vehicles. This review introduces functionalized hydrogels for musculoskeletal disorder treatment using gene therapy procedures, from gene therapy principles to functionalized hydrogels and applications of hydrogel-mediated gene therapy for musculoskeletal disorders, while remaining challenges are discussed from the perspective of translation in patients., Competing Interests: Declaration of competing interest The authors have no competing interests to declare., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Pesticides can have harmful impacts on the environment and living organisms. Thus, removing them from polluted water is crucial. In this study, a bionanocomposite of carboxymethyl tragacanth-grafted-poly(3-aminophenol)/zinc oxide@iron oxide (CMT-g-P3AP/ZnO@Fe 3 O 4 ) synthesized by in situ copolymerization as an efficient adsorbent to eliminate the acetamiprid pesticide from polluted water. The CMT-g-P3AP/ZnO@Fe 3 O 4 magnetic nanocomposite was analyzed utilizing various techniques including FTIR, EDX, FESEM, XRD, BET, CHNSO, and TGA. The results displayed that the resulting nanocomposite with maximum adsorption capacity (Q max ) successfully removed the acetamiprid pesticide from polluted water under optimal conditions such as pH of 7.00, 5.00 mg of adsorbent, 20.0 min duration, and 400 mg/L acetamiprid concentration. According to the linear Langmuir isotherm, the Q max of the biosorbent was 833 mg/g. The experimental adsorption data fitted well with Temkin's nonlinear isotherm model. The adsorption kinetic data were closely related to the Weber-Morris intraparticle diffusion nonlinear model. After three repetitive cycles, CMT-g-P3AP/ZnO@Fe 3 O 4 can be outstandingly renewed and recycled without significant reduction in its adsorption efficacy, as evidenced by the adsorption-desorption experiments. In addition, the CMT-g-P3AP/ZnO@Fe 3 O 4 displayed the good antibacterial activity against E. coli and S. aureus., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

There is usually a trade-off between high mechanical strength and dynamic self-healing because the mechanisms of these properties are mutually exclusive. Herein, we design and fabricate a fluorinated phenolic polyurethane (FPPU) elastomer based on octafluoro-4,4'-biphenol to overcome this challenge. This fluorine-based motif not only tunes interchain interactions through π-π stacking between aromatic rings and free-volume among polymer chains but also improves the reversibility of phenol-carbamate bonds via electron-withdrawing effect of fluorine atoms. The developed FPPU elastomer shows the highest recorded puncture energy (648.0 mJ), high tensile strength (27.0 MPa), as well as excellent self-healing efficiency (92.3%), along with low surface energy (50.9 MJ m -2 ), notch-insensitivity, and reprocessability compared with non-fluorinated counterpart biphenolic polyurethane (BPPU) elastomer. Taking advantage of the above-mentioned merits of FPPU elastomer, we prepare an anti-fouling triboelectric nanogenerator (TENG) with a self-healable, and reprocessable elastic substrate. Benefiting from stronger electron affinity of fluorine atoms than hydrogen atoms, this electronic device exhibits ultrahigh peak open-circuit voltage of 302.3 V compared to the TENG fabricated from BPPU elastomer. Furthermore, a healable and stretchable conductive composite is prepared. This research provides a distinct and general pathway toward constructing high-performance elastomers and will enable a series of new applications., (Copyright © 2024. Published by Elsevier B.V.)

Injectable hydrogels based on biopolymers, fabricated utilizing diverse chemical and physical methodologies, exhibit exceptional physical, chemical, and biological properties. They have multifaceted applications encompassing wound healing, tissue regeneration, and across diverse scientific realms. This review critically evaluates their largely uncharted potential in ophthalmology, elucidating their diverse applications across an array of ocular diseases. These conditions include glaucoma, cataracts, corneal disorders (spanning from age-related degeneration to trauma, infections, and underlying chronic illnesses), retina-associated ailments (such as diabetic retinopathy, retinitis pigmentosa, and age-related macular degeneration (AMD)), eyelid abnormalities, and uveal melanoma (UM). This study provides a thorough analysis of applications of injectable hydrogels based on biopolymers across these ocular disorders. Injectable hydrogels based on biopolymers can be customized to have specific physical, chemical, and biological properties that make them suitable as drug delivery vehicles, tissue scaffolds, and sealants in the eye. For example, they can be engineered to have optimum viscosity to be injected intravitreally and sustain drug release to treat retinal diseases. Their porous structure and biocompatibility promote cellular infiltration to regenerate diseased corneal tissue. By accentuating their indispensable role in ocular disease treatment, this review strives to present innovative and targeted approaches in this domain, thereby advancing ocular therapeutics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The current study developed an innovative design for the production of smart multifunctional core-double shell superparamagnetic nanoparticles (NPs) with a focus on the development of a pH-responsive drug delivery system tailored for the controlled release of Phenytoin, accompanied by real-time monitoring capabilities. In this regard, the ultra-small superparamagnetic iron oxide@silica NPs (IO@Si MNPs) were synthesized and then coated with a layer of gelatin containing Phenytoin as an antiepileptic drug. The precise saturation magnetization value for the resultant NPs was established at 26 emu g -1 . The polymeric shell showed a pH-sensitive behavior with the capacity to regulate the release of encapsulated drug under neutral pH conditions, simultaneously, releasing more amount of the drug in a simulated tumorous-epileptic acidic condition. The NPs showed an average size of 41.04 nm, which is in the desired size range facilitating entry through the blood-brain barrier. The values of drug loading and encapsulation efficiency were determined to be 2.01 and 10.05%, respectively. Moreover, kinetic studies revealed a Fickian diffusion process of Phenytoin release, and diffusional exponent values based on the Korsmeyer-Peppas equation were achieved at pH 7.4 and pH 6.3. The synthesized NPs did not show any cytotoxicity. Consequently, this new design offers a faster release of PHT at the site of a tumor in response to a change in pH, which is essential to prevent epileptic attacks., (© 2024. The Author(s).)

Cancer, a global health challenge of utmost severity, necessitates innovative approaches beyond conventional treatments (e.g., surgery, chemotherapy, and radiation therapy). Unfortunately, these approaches frequently fail to achieve comprehensive cancer control, characterized by inefficacy, non-specific drug distribution, and the emergence of adverse side effects. Nanoscale systems based on natural polymers like chitosan have garnered significant attention as promising platforms for cancer diagnosis and therapy owing to chitosan's inherent biocompatibility, biodegradability, nontoxicity, and ease of functionalization. Herein, recent advancements pertaining to the applications of chitosan nanoparticles in cancer imaging and drug/gene delivery are deliberated. The readers are introduced to conventional non-stimuli-responsive and stimuli-responsive chitosan-based nanoplatforms. External triggers like light, heat, and ultrasound and internal stimuli such as pH and redox gradients are highlighted. The utilization of chitosan nanomaterials as contrast agents or scaffolds for multimodal imaging techniques e.g., magnetic resonance, fluorescence, and nuclear imaging is represented. Key applications in targeted chemotherapy, combination therapy, photothermal therapy, and nucleic acid delivery using chitosan nanoformulations are explored for cancer treatment. The immunomodulatory effects of chitosan and its role in impacting the tumor microenvironment are analyzed. Finally, challenges, prospects, and future outlooks regarding the use of chitosan-based nanosystems are discussed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Despite the advantages of topical administration in the treatment of skin diseases, current marketed preparations face the challenge of the skin's barrier effect, leading to low therapeutic effectiveness and undesirable side effects. Hence, in recent years the management of skin wounds, the main morbidity-causing complication in hospital environments, and atopic dermatitis, the most common inflammatory skin disease, has become a great concern. Fortunately, new, more effective, and safer treatments are already under development, with chitosan, starch, silk fibroin, agarose, hyaluronic acid, alginate, collagen, and gelatin having been used for the development of nanoparticles, liposomes, niosomes and/or hydrogels to improve the delivery of several molecules for the treatment of these diseases. Biocompatibility, biodegradability, increased viscosity, controlled drug delivery, increased drug retention in the epidermis, and overall mitigation of adverse effects, contribute to an effective treatment, additionally providing intrinsic antimicrobial and wound healing properties. In this review, some of the most recent success cases of biopolymer-based drug delivery systems as part of nanocarriers, semi-solid hydrogel matrices, or both (hybrid systems), for the management of skin wounds and atopic dermatitis, are critically discussed, including composition and in vitro, ex vivo and in vivo characterization, showing the promise of these external drug delivery systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Soft robots have the potential to assist and complement human exploration of extreme and harsh environments (i.e., organic solvents). However, soft robots with stable performance in diverse organic solvents are not developed yet. In the current research, a non-Euclidean-plate under-liquid soft robot inspired by jellyfish based on phototropic liquid crystal elastomers is fabricated via a 4D-programmable strategy. Specifically, the robot employs a 3D-printed non-Euclidean-plate, designed with Archimedean orientation, which undergoes autonomous deformation to release internal stress when immersed in organic solvents. With the assistance of near-infrared light illumination, the organic solvent inside the robot vaporizes and generates propulsion in the form of bubble streams. The developed NEP-Jelly-inspired soft robot can swim with a high degree of freedom in various organic solvents, for example, N, N-dimethylformamide, N, N-dimethylacetamide, tetrahydrofuran, dichloromethane, and trichloromethane, which is not reported before. Besides bionic jellyfish, various aquatic invertebrate-inspired soft robots can potentially be prepared via a similar 4D-programmable strategy., (© 2024 Wiley‐VCH GmbH.)

The limited capacity of typical materials to resist stress loading, which affects their mechanical performance, is one of the most formidable challenges in materials science. Here, we propose a bone-inspired stress-gaining concept of converting typically destructive stress into a favorable factor to substantially enhance the mechanical properties of elastomers. The concept was realized by a molecular design of dynamic poly(oxime-urethanes) network with mesophase domains. During external loading, the mesophase domains in the condensed state were aligned into more ordered domains, and the dynamic oxime-urethane bonds served as the dynamic molecular locks disassociating and reorganizing to facilitate and fix the mesophase domains. Consequently, the tensile modulus and strength were enhanced by 1744 and 49.3 times after four cycles of mechanical training, respectively. This study creates a molecular concept with stress-gaining properties induced by repeated mechanical stress loading and will inspire a series of innovative materials for diverse applications.

Polymer microcapsules containing cyanoacrylates have represented a promising option to develop self-healing biomaterials. This study aims to develop an electrospray method for the preparation of capsules using poly(methyl methacrylate) (PMMA) as the encapsulant and ethyl 2-cyanoacrylate (EC) as the encapsulate. It also aims to study the effect of the electrospray process parameters on the size and morphology of the capsules. The capsules were characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and field-emission scanning electron microscopy (FE-SEM). Moreover, the effects of electrospray process parameters on the size were investigated by Taguchi experimental design. FTIR and TGA approved the presence of both PMMA and EC without further reaction. FE-SEM micrograph demonstrated that an appropriate choice of solvents, utilizing an appropriate PMMA:EC ratio and sufficient PMMA concentration are critical factors to produce capsules dominantly with an intact and spherical morphology. Utilizing various flow rates (0.3-0.5 ml/h) and applied voltage (18-26 kV), capsules were obtained with a 600-1000 nm size range. At constantly applied voltages, the increase in flow rate increased the capsule size up to 40% (ANOVA, p ≤ 0.05), while at constant flow rates, the increase in applied voltage reduced the average capsule size by 3.4-26% (ANOVA, p ≤ 0.05). The results from the Taguchi design represented the significance of solution flow rate, applied voltage, and solution concentration. It was shown that the most effective parameter on the size of capsules is flow rate. This research demonstrated that electrospray can be utilized as a convenient method for the preparation of sub-micron PMMA capsules containing EC. Furthermore, the morphology of the capsules is dominated by solvents, PMMA concentration, and PMMA:EC ratio, while the average size of the capsules can be altered by adjusting the flow rate and applied voltage of the electrospray process., (© 2024. The Author(s).)

Stretchable conductive fibers play key roles in electronic textiles, which have substantial improvements in terms of flexibility, breathability, and comfort. Compared to most existing electron-conductive fibers, ion-conductive fibers are usually soft, stretchable, and transparent, leading to increasing attention. However, the integration of desirable functions including high transparency, stretchability, conductivity, solvent resistance, self-healing ability, processability, and recyclability remains a challenge to be addressed. Herein, a new molecular strategy based on dynamic covalent cross-linking networks is developed to enable continuous melt spinning of the ionogel fiber with the aforementioned properties. As a proof of concept, adaptable covalently cross-linked ionogel fibers based on dimethylglyoximeurethane (DOU) groups (DOU-IG fiber) are prepared. The resultant DOU-IG fiber exhibited high transparency (>93%), tensile strength (0.76 MPa), stretchability (784%), and solvent resistance. Owing to the dynamic of DOU groups, the DOU-IG fiber shows high healing performance using near-infrared light. Taking advantage of DOU-IG fibers, multifunctional ionotronics with the integration of several desirable functionalities including sensor, triboelectric nanogenerator, and electroluminescent display are fabricated and used for motion monitoring, energy harvesting, and human-machine interaction. It is believed that these DOU-IG fibers are promising for fabricating the next generation of electronic textiles and other wearable electronics., (© 2023 Wiley‐VCH GmbH.)

As stretchable conductive materials, ionogels have gained increasing attention. However, it still remains crucial to integrate multiple functions including mechanically robust, room temperature self-healing capacity, facile processing, and recyclability into an ionogel-based device with high potential for applications such as soft robots, electronic skins, and wearable electronics. Herein, inspired by the structure of spider silk, a multilevel hydrogen bonding strategy to effectively produce multi-functional ionogels is proposed with a combination of the desirable properties. The ionogels are synthesized based on N-isopropylacrylamide (NIPAM), N, N-dimethylacrylamide (DMA), and ionic liquids (ILs) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]). The synergistic hydrogen bonding interactions between PNIPAM chains, PDMA chains, and ILs endow the ionogels with improved mechanical strength along with fast self-healing ability at ambient conditions. Furthermore, the synthesized ionogels show great capability for the continuous fabrication of the ionogel-based fibers using the melt-spinning process. The ionogel fibers exhibit spider-silk-like features with hysteresis behavior, indicating their excellent energy dissipation performance. Moreover, an interwoven network of ionogel fibers with strain and thermal sensing performance can accurately sense the location of objects. In addition, the ionogels show great recyclability and processability into different shapes using 3D printing. This work provides a new strategy to design superior ionogels for diverse applications., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Today, tissue engineering strategies need the improvement of advanced hydrogels with biological and mechanical properties similar to natural cartilage for joint regeneration. In this study, an interpenetrating network (IPN) hydrogel composed of gelatin methacrylate (GelMA)/alginate (Algin)/nano-clay (NC) with self-healing ability was developed with particular consideration to balancing of the mechanical properties and biocompatibility of bioink material. Subsequently, the properties of the synthesized nanocomposite IPN, including the chemical structure, rheological behavior, physical properties (i.e. porosity and swelling), mechanical properties, biocompatibility, and self-healing performance were evaluated to investigate the potential application of the developed hydrogel for cartilage tissue engineering (CTE). The synthesized hydrogels showed highly porous structures with dissimilar pore sizes. The results revealed that the NC incorporation improved the properties of GelMA/Algin IPN, such as porosity, and mechanical strength (reached 170 ± 3.5 kPa), while the NC incorporation decreased the degradation (63.8 %) along with retaining biocompatibility. Therefore, the developed hydrogel showed a promising potential for the treatment of tissue defects in cartilage., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Although highly desired, it is difficult to develop mechanically robust and room temperature self-healing ionic liquid-based gels (ionogels), which are very promising for next-generation stretchable electronic devices. Herein, it is discovered that the ionic liquid significantly reduces the reversible reaction rate of disulfide bonds without altering its thermodynamic equilibrium constant via small molecule model reaction and activation energy evolution of the dissociation of the dynamic network. This inhibitory effect would reduce the dissociated units in the dynamic polymeric network, beneficial for the strength of the ionogel. Furthermore, aromatic disulfide bonds with high reversibility are embedded in the polyurethane to endow the ionogel with superior room temperature self-healing performance. Isocyanates with an asymmetric alicyclic structure are chosen to provide optimal exchange efficiencies for the embedded disulfide bonds relative to aromatic and linear aliphatic. Carbonyl-rich poly(ethylene-glycol-adipate) diols are selected as soft segments to provide sufficient interaction sites for ionic liquids to endow the ionogel with high transparency, stretchability, and elasticity. Finally, a self-healing ionogel with a tensile strength of 1.65 ± 0.08 MPa is successfully developed, which is significantly higher than all the reported transparent room temperature self-healing ionogel and its application in a 3D printed stretchable numeric keyboard is exemplified., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Electrotherapy is a promising tissue repair technique. However, electrotherapy devices are frequently complex and must be placed adjacent to injured tissue, thereby limiting their clinical application. Here, we propose a general strategy to facilitate tissue repair by modulating endogenous electric fields with nonadjacent (approximately 44 mm) wireless electrotherapy through a 3D-printed entirely soft and bioresorbable triboelectric nanogenerator based stimulator, without any electrical accessories, which has biomimetic mechanical properties similar to those of soft tissue. In addition, the feasibility of using the stimulator to construct an electrical double layer with tissue for nonadjacent wireless electrotherapy was demonstrated by skin and muscle injury models. The treated groups showed significantly improved tissue repair compared with the control group. In conclusion, we developed a promising electrotherapy strategy and may inspire next-generation electrotherapy for tissue repair.

Conductive fibers are vital for next-generation wearable and implantable electronics. However, the mismatch of mechanical, electrical, and biological properties between existing conductive fibers and human tissues significantly retards their further development. Here, the concept of neuro-like fibers to meet these aforementioned requirements is proposed. A new wet spinning process is established to continuously produce pure gelatin hydrogel fibers. The key is the controllable and rapid gelation of spinning solutions based on the salting-out effect, which is inspired by the Chinese food tofu. The resultant fibers exhibit neuro-like features of soft-while-strong mechanical properties, high ionic conductivity, and superior biological properties including biodegradability, biocompatibility, and edibility, which are crucial for implanted applications but seldom reported. Furthermore, all-weather suitable neuro-like fibers with excellent anti-freezing and water retention properties are developed by introducing glycerol for wearable applications. The optical fiber, transient electronics, and electronic data glove made of neuro-like fibers profoundly demonstrate their potential in biomedical applications., (© 2023 Wiley-VCH GmbH.)

Self-powered information encoding devices (IEDs) have drawn considerable interest owing to their capability to process information without batteries. Next-generation IEDs should be reprogrammable, self-healing, and wearable to satisfy the emerging requirements for multifunctional IEDs; however, such devices have not been demonstrated. Herein, an integrated triboelectric nanogenerator-based IED with the aforementioned features was developed based on the designed light-responsive high-permittivity poly(sebacoyl diglyceride- co -4,4'-azodibenzoyl diglyceride) elastomer (PSeDAE) with a triple-shape-memory effect. The electrical memory feature was achieved through a microscale shape-memory property, enabling spatiotemporal information reprogramming for the IED. Macroscale shape-memory behavior afforded the IED shape-reprogramming ability, yielding wearable and detachable features. The dynamic transesterifications and light-heating groups in the PSeDAE afforded a remotely controlled rearrangement of its cross-linking network, producing the self-healing IED.

Hydrogels are emerging as the most promising dressings due to their excellent biocompatibility, extracellular matrix mimicking structure, and drug loading ability. However, existing hydrogel dressings exhibit limited breathability, poor environmental adaptability, potential drug resistance, and limited drug options, which extremely restrict their therapeutic effect and working scenarios. Here, the current research introduces the first paradigm of hydrogel textile dressings based on novel gelatin glycerin hydrogel (glyhydrogel) fibers fabricated by the Hofmeister effect based wet spinning. Benefiting from the unique knitted structure, the textile dressing features excellent breathability (1800 times that of the commercially available 3 M dressing) and stretchability (535.51 ± 38.66%). Furthermore, the glyhydrogel textile dressing can also withstand the extreme temperature of -80 °C, showing the potential for application in subzero environments. Moreover, the introduction of glycerin endows the textile dressing with remarkable antibacterial property and expands the selection of loaded drugs (e.g., clindamycin). The prepared glyhydrogel textile dressing shows an excellent infected wound healing effect with a complete rat skin closure within 14 days. All these functions have not been achievable by traditional hydrogel dressings and provide a new approach for the development of hydrogel dressings., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors.)

Flammability is a great challenge in the fields of electronics. The emergence of triboelectric nanogenerators (TENGs) provides a safe way to harvest environmentalally friendly energy and convert it into more secure power sources. Especially, polymer-based TENGs significantly accelerate the practical application of self-powered flexible electronics. However, most of the existing polymeric materials for TENGs are easily flammable and melt, dripping, in a fire scenario, and cannot be reused after combustion, which greatly limits the application of TENGs under extreme conditions. Herein, a fire-resistant TENG based on all-aromatic liquid crystalline poly(aryl ether ester) (LCP AEE ) synthesized via simple and efficient one-pot melt polycondensation is reported. The highly rigid main chain of LCP AEE endows the LCP-TENG with outstanding anti-dripping, temperature- and fire-resistance. The resultant LCP-TENG exhibits excellent electrical output performance, which is attributed to the high dielectric constant (ε' = 4.8) and fibrous-structured morphology of LCP AEE . The device can maintain over 65% of open-circuit voltage even after 16 s combustion (≈520 °C). Consequently, this work offers a novel strategy for tailoring the TENGs toward a secure power generator and electronics with fire hazard reduction, and potential application in firefighting, personal protection, and other extreme temperature environments., (© 2022 Wiley-VCH GmbH.)

Biodegradable electronics are considered as an important bio-friendly solution for electronic waste (e-waste) management, sustainable development, and emerging implantable devices. Elastic electronics with higher imitative mechanical characteristics of human tissues, have become crucial for human-related applications. The convergence of biodegradability and elasticity has emerged a new paradigm of next-generation electronics especially for wearable and implantable electronics. The corresponding biodegradable elastic materials are recognized as a key to drive this field toward the practical applications. The review first clarifies the relevant concepts including biodegradable and elastic electronics along with their general design principles. Subsequently, the crucial mechanisms of the degradation in polymeric materials are discussed in depth. The diverse types of biodegradable elastomers and gels for electronics are then summarized. Their molecular design, modification, processing, and device fabrication especially the structure-properties relationship as well as recent advanced are reviewed in detail. Finally, the current challenges and the future directions are proposed. The critical insights of biodegradability and elastic characteristics in the elastomers and gel allows them to be tailored and designed more effectively for electronic applications., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

In order to study the release of cerium nitrate in a self-healing epoxy-based coating, poly (urea-formaldehyde) (PUF) microcapsules containing cerium nitrate were synthesized. The effects of healing agent concentration and weight percent of microcapsules in the epoxy resin were studied through the incorporation of microcapsules within an epoxy-based coating. The prepared microcapsules were characterized using thermogravimetric analysis and Fourier transform infrared spectroscopy and confirmed the successful encapsulation of cerium nitrate within PUF capsules. The self-healing performance of the prepared epoxy coating was investigated in 0.6 M NaCl solution using electrochemical impedance spectroscopy (EIS) tests. The EIS results indicated the successful release of encapsulated cerium nitrate from PUF microcapsules once the damage occurred in the epoxy coating, which led to effective self-healing of the epoxy-based coating. The presence of chlorine and cerium ions in the solution led to the precipitation of cerium hydroxides and oxides in the scratched area as a passive layer which hindered the corrosion in the damaged area. In addition, the EIS results showed that the healing performance of the coatings depends on the weight percent of microcapsules and the concentration of the self-healing agent. The highest self-healing performance was achieved for the maximum amount of microcapsule incorporation (10 wt %), while the increase in the microcapsule percent led to a decrease in the adhesion of the coating to the substrate., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Functionalized polyacrylonitrile (PAN) nanofibers were used in the present investigation to enhance the fracture behavior of carbon epoxy composite in order to prevent delamination if any crack propagates in the resin rich area. The main intent of this investigation was to analyze the efficiency of PAN nanofiber as a reinforcing agent for the carbon fiber-based epoxy structural composite. The composites were fabricated with stacked unidirectional carbon fibers and the PAN powder was functionalized with glycidyl methacrylate (GMA) and then used as reinforcement. The fabricated composites' fracture behavior was analyzed through a double cantilever beam test and the energy release rate of the composites was investigated. The neat PAN and functionalized PAN-reinforced samples had an 18% and a 50% increase in fracture energy, respectively, compared to the control composite. In addition, the samples reinforced with functionalized PAN nanofibers had 27% higher interlaminar strength compared to neat PAN-reinforced composite, implying more efficient stress transformation as well as stress distribution from the matrix phase (resin-rich area) to the reinforcement phase (carbon/phase) of the composites. The enhancement of fracture toughness provides an opportunity to alleviate the prevalent issues in laminated composites for structural operations and facilitate their adoption in industries for critical applications.

This investigation is carried out to understand the effects of water absorption on the mechanical properties of hybrid phenol formaldehyde (PF) composite fabricated with Areca Fine Fibres (AFFs) and Calotropis Gigantea Fibre (CGF). Hybrid CGF/AFF/PF composites were manufactured using the hand layup technique at varying weight percentages of fibre reinforcement (25, 35 and 45%). Hybrid composite having 35 wt.% showed better mechanical properties (tensile strength ca. 59 MPa, flexural strength ca. 73 MPa and impact strength 1.43 kJ/m 2 ) under wet and dry conditions as compared to the other hybrid composites. In general, the inclusion of the fibres enhanced the mechanical properties of neat PF. Increase in the fibre content increased the water absorption, however, after 120 h of immersion, all the composites attained an equilibrium state.

The massive plastic production worldwide leads to a global concern for the pollution made by the plastic wastes and the environmental issues associated with them. One of the best solutions is replacing the fossil-based plastics with bioplastics. Bioplastics such as polylactic acid (PLA) are biodegradable materials with less greenhouse gas (GHG) emissions. PLA is a biopolymer produced from natural resources with good mechanical and chemical properties, therefore, it is used widely in packaging, agriculture, and biomedical industries. PLA products mostly end up in landfills or composting. In this review paper, the existing life cycle assessments (LCA) for PLA were comprehensively reviewed and classified. According to the LCAs, the energy and materials used in the whole life cycle of PLA were reported. Finally, the GHG emissions of PLA in each stage of its life cycle, including feedstock acquisition and conversion, manufacturing of PLA products, the PLA applications, and the end of life (EoL) options, were described. The most energy-intensive stage in the life cycle of PLA is its conversion. By optimizing the conversion process of PLA, it is possible to make it a low-carbon material with less dependence on energy sources.

Polyethylene (PE) is one the most used plastics worldwide for a wide range of applications due to its good mechanical and chemical resistance, low density, cost efficiency, ease of processability, non-reactivity, low toxicity, good electric insulation, and good functionality. However, its high flammability and rapid flame spread pose dangers for certain applications. Therefore, different flame-retardant (FR) additives are incorporated into PE to increase its flame retardancy. In this review article, research papers from the past 10 years on the flame retardancy of PE systems are comprehensively reviewed and classified based on the additive sources. The FR additives are classified in well-known FR families, including phosphorous, melamine, nitrogen, inorganic hydroxides, boron, and silicon. The mechanism of fire retardance in each family is pinpointed. In addition to the efficiency of each FR in increasing the flame retardancy, its impact on the mechanical properties of the PE system is also discussed. Most of the FRs can decrease the heat release rate (HRR) of the PE products and simultaneously maintains the mechanical properties in appropriate ratios. Based on the literature, inorganic hydroxide seems to be used more in PE systems compared to other families. Finally, the role of nanotechnology for more efficient FR-PE systems is discussed and recommendations are given on implementing strategies that could help incorporate flame retardancy in the circular economy model.

The onset of coronavirus pandemic has sparked a shortage of facemasks in almost all nations. Without this personal protective equipment, healthcare providers, essential workers, and the general public are exposed to the risk of infection. In light of the aforementioned, it is critical to balance the supply and demand for masks. COVID-19 will also ensure that masks are always considered as an essential commodity in future pandemic preparedness. Moreover, billions of facemasks are produced from petrochemicals derived raw materials, which are non-degradable upon disposal after their single use, thus causing environmental pollution and damage. The sustainable way forward is to utilise raw materials that are side-stream products of local industries to develop facemasks having equal or better efficiency than the conventional ones. In this regard, wheat gluten biopolymer, which is a by-product or co-product of cereal industries, can be electrospun into nanofibre membranes and subsequently carbonised at over 700 °C to form a network structure, which can simultaneously act as the filter media and reinforcement for gluten-based masks. In parallel, the same gluten material can be processed into cohesive thin films using plasticiser and hot press. Additionally, lanosol, a naturally-occurring substance, imparts fire (V-0 rating in vertical burn test), and microbe resistance in gluten plastics. Thus, thin films of flexible gluten with very low amounts of lanosol (<10 wt%) can be bonded together with the carbonised mat and shaped by thermoforming to create the facemasks. The carbon mat acting as the filter can be attached to the masks through adapters that can also be made from injection moulded gluten. The creation of these masks could simultaneously be effective in reducing the transmittance of infectious diseases and pave the way for environmentally benign sustainable products., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Wheat gluten biopolymers generally become excessively rigid when processed without plasticisers, while the use of plasticisers, on the other hand, can deteriorate their mechanical properties. As such, this study investigated the effect of carbon black (CB) as a filler into glycerol-plasticised gluten to prepare gluten/CB biocomposites in order to eliminate the aforementioned drawback. Thus, biocomposites were manufactured using compression moulding followed by the determination of their mechanical, morphological, and chemical properties. The filler content of 4 wt% was found to be optimal for achieving increased tensile strength by 24%, and tensile modulus by 268% along with the toughness retention based on energy at break when compared with those of glycerol-plasticised gluten. When reaching the filler content up to 6 wt%, the tensile properties were found to be worsened, which can be ascribed to excessive agglomeration of carbon black at the high content levels within gluten matrices. Based on infrared spectroscopy, the results demonstrate an increased amount of β-sheets, suggesting the formation of more aggregated protein networks induced by increasing the filler contents. However, the addition of fillers did not improve fire and water resistance in such bionanocomposites owing to the high blend ratio of plasticiser to gluten.

This review paper initially summarizes the latest developments in impact testing on polymer matrix composites collating the various analytical, numerical, and experimental studies performed since the year 2000. Subsequently, the scientific literature investigating nanofiller reinforced polymer composite matrices as well as self-healing polymer matrix composites by incorporating core-shell nanofibers is reviewed in-depth to provide a perspective on some novel advances in nanotechnology that have led to composite developments. Through this review, researchers can gain a representative idea of the state of the art in nanotechnology for polymer matrix composite engineering, providing a platform for further study of this increasingly industrially significant material, and to address the challenges in developing the next generation of advanced, high-performance materials., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.