Search Results (101)

Asphalt pavement cracking is an important factor affecting its service life. Under certain conditions, the self-healing behavior of asphalt itself can repair pavement cracks. However, the self-healing ability of asphalt itself is limited. In order to strengthen the self-healing ability of asphalt, the microcapsule wrapped with a repair agent is pre-mixed into the asphalt mixture. When the crack occurs and spreads to the surface of the microcapsule, the microcapsule ruptures and the healing agent flows out to realize the self-healing of the crack. Current microcapsules are mostly prepared with healing agents and bio-oil as core materials, and their high-temperature resistance to rutting is poor. While the epoxy resin contains a three-membered cyclic ether, it can undergo ring-opening polymerization to bond and repair the asphalt matrix. In addition, research on microcapsules mainly focuses on the self-healing properties of microcapsule-modified asphalt. In fact, before adding microcapsules to asphalt to improve its self-healing performance, it is necessary to ensure that the asphalt has a good road performance. On this basis, the self-healing performance of asphalt is improved, thereby extending the service life of asphalt pavement. Therefore, two-component epoxy self-healing microcapsules (E-mic and G-mic) were first prepared in this paper. Then, a temperature scanning test, rheological test of bending beams, and linear amplitude scanning test were, respectively, conducted for the microcapsule/asphalt to evaluate its road performance, including the high-temperature performance, low-temperature crack resistance, and fatigue performance. Finally, the self-healing performance of microcapsules/asphalt was tested. The results showed that the self-developed epoxy self-healing microcapsules were well encapsulated and presented as spherical micron-sized particles. The average particle size of the E-mic was approximately 23.582 μm, while the average particle size of the G-mic was approximately 22.440 μm, exhibiting a good normal distribution. In addition, they can remain intact and unbroken under high-temperature conditions. The results of road performance tests indicated that the microcapsule/asphalt mixture exhibits an excellent high-temperature resistance to permanent deformation, low-temperature crack resistance, and fatigue resistance. The self-healing test demonstrated that the microcapsule/asphalt exhibited an excellent self-healing performance. When the microcapsule content was 4%, the self-healing rate reached its optimal level of 67.8%, which was 149.2% higher than that of the base asphalt. Full article

Microbial contamination is a global concern with impacts on a variety of industries ranging from marine to biomedical applications. Recent research on hydrophilic polymer-based coatings is focused on combining antifouling polymers with nanomaterials to enhance mechanical, optical, and stimuli-responsive properties, yielding colour changing, self-healing, and super hydrophilic materials. This study combines the hydrophilic and antifouling properties of vitamin B5 analogous methacrylamide (B5AMA)-based polymers with stimuli-responsive anthocyanin-dye-loaded cellulose nanocrystals (CNCs) to develop antifouling materials with colour changing capabilities upon bacterial contamination. Poly(B5AMA)-grafted CNCs were prepared through surface-initiated photoiniferter reversible addition fragmentation chain transfer (SP-RAFT) polymerization and characterized through proton nuclear magnetic resonance (¹H-NMR), transmission electron microscopy (SEM/TEM), and X-ray photon spectroscopy (XPS) to confirm the formation of surface-grafted polymer chains. The bare CNCs and poly(B5AMA)-grafted CNCs were loaded with anthocyanin dye and evaluated for pH-dependent colour changing capabilities. Interestingly, anthocyanin-loaded CNCs demonstrated vibrant colour changes in both solution and dried film form upon bacterial contamination; however, limited colour changing capabilities of the composites, specifically in dried film form, were attributed to the enhanced dispersibility and antifouling capabilities of the polymer-coated CNCs. Full article

Liquid metals (LMs), with their unique combination of high electrical conductivity and mechanical deformability, have emerged as promising materials for stretchable electronics and biointerfaces. However, the practical application of bulk LMs in wearable sensors has been hindered by processing challenges and low stability. To overcome these limitations, liquid metal particles (LMPs) encapsulated by native oxide shells have gained attention as versatile and stable fillers for stretchable and conductive composites. Recent advances have focused on the development of LM-based hybrid composites that combine LMPs with metal, carbon, or polymeric fillers. These systems offer enhanced electrical and mechanical properties and can form conductive networks without the need for additional sintering processes. They also impart composites with multiple functions such as self-healing, electromagnetic interference shielding, and recyclability. Hence, the present review summarizes the fabrication methods and functional properties of LM-based composites, with a particular focus on their applications in wearable sensing. In addition, recent developments in the use of LM composites for physical motion monitoring (e.g., strain and pressure sensing) and electrophysiological signal recording (e.g., EMG and ECG) are presented, and the key challenges and opportunities for next-generation wearable platforms are discussed. Full article

Postoperative adhesions are a prevalent complication following abdominal surgeries, often leading to significant clinical challenges. This study introduces an innovative solution utilizing a polyethylene glycol (PEG)-based triblock copolymer to form an injectable, self-healing hydrogel aimed at preventing these adhesions. The hydrogel, formulated with temperature-responsive and self-healing properties through the incorporation of poly (N-isopropyl acrylamide) (PNIPAM) and anion–pi interactions, was synthesized using reversible addition–fragmentation chain transfer (RAFT) polymerization. The hydrogel’s physical properties, biocompatibility, hemostatic effect, and anti-adhesive capabilities were rigorously tested through in vitro and in vivo experiments involving rat models. It demonstrated excellent biocompatibility, effective tissue adhesion, and robust hemostatic properties. Most notably, it exhibited significant anti-adhesive effects in a rat abdominal wall–cecum model, reducing adhesion formation effectively compared to controls. The PEG-based injectable hydrogel presents a promising approach for postoperative adhesion prevention. Its ability to gel in situ triggered by body heat, coupled with its self-healing properties, provides a substantial advantage in clinical settings, indicating its potential utility as a novel anti-adhesion material. Full article

Dicyclopentadiene (DCPD)–poly(methyl methacrylate) (PMMA) core–shell fibers were fabricated via coaxial electrospinning to develop a self-healing polymer composite. A PMMA shell containing a first-generation Grubbs catalyst was co-spun with a DCPD core at 0.5 mL h⁻¹ and 28 kV, yielding smooth, cylindrical fibers. The diameter range of nanofibers was 300–900 nm, with 95% below 800 nm, as confirmed by FESEM image analysis. FTIR spectroscopy monitored shell integrity via the PMMA C=O stretch and core polymerization via the trans-C=C bands. The high presence of the 970 cm⁻¹ band in the healed nanofiber mat and the minor appearance in the uncut core–shell mat demonstrated successful DCPD polymerization mostly where the intended damage was. The optical clarity of PMMA enabled the direct monitoring of healing progress via optical microscopy. The presented findings demonstrate that PMMA can retain a liquid active core and catalyst to form a polymer layer on a damaged site and could be used as a model material for other self-healing systems that require healing monitoring. Full article

Polyimine-based composites have emerged as a promising class of dynamic covalent thermosets, combining high mechanical strength, thermal stability, self-healing, recyclability, and reprocessability. This review systematically summarizes recent advances in polyimine synthesis, highlighting dynamic covalent chemistry (DCC) strategies such as imine exchange and reversible Schiff base reactions. Structural customization can be achieved by incorporating reinforcing phases such as carbon nanotubes, graphene, and bio-based fibers. Advanced fabrication methods—including solution casting, hot pressing, and interfacial polymerization—enable precise integration of these components while preserving structural integrity and adaptability. Mechanical performance analysis emphasizes the interplay between dynamic bonds, interfacial engineering, and multiscale design strategies. Polyimine composites exhibit outstanding performance characteristics, including a self-healing efficiency exceeding 90%, a tensile strength reaching 96.2 MPa, and remarkable chemical recyclability. Emerging engineering applications encompass sustainable green materials, flexible electronics, energy storage devices, and flame-retardant systems. Key challenges include balancing multifunctionality, enhancing large-scale processability, and developing low-energy recycling strategies. Future efforts should focus on interfacial optimization and network adaptivity to accelerate the industrial translation of polyimine composites, advancing next-generation sustainable materials. Full article

Nanogels are polymer-based, crosslinked hydrogel particles on the nanometer scale. Nanogels developed from synthetic and natural polymers have gathered a great deal of attention in industry and scientific society due to having an increased surface area, softness, flexibility, absorption, and drug loading ability, as well as their mimicking the environment of a tissue. Nanogels having biocompatibility, nontoxic and biodegradable properties with exceptional design, fabrication, and coating facilities may be used for a variety of different biomedical applications, such as drug delivery and therapy, tissue engineering, and bioimaging. Nanogels fabricated by chemical crosslinking and physical self-assembly displayed the ability to encapsulate therapeutics, including hydrophobic, hydrophilic, and small molecules, proteins, peptides, RNA and DNA sequences, and even ultrasmall nanoparticles within their three-dimensional polymer networks. One of the many drug delivery methods being investigated as a practical option for targeted delivery of drugs for cancer treatment is nanogels. The delivery of DNA and anticancer drugs like doxorubicin, epirubicin, and paclitaxel has been eased by polymeric nanogels. Stimuli-responsive PEGylated nanogels have been reported as smart nanomedicines for cancer diagnostics and therapy. Another promising biomedical application of nanogels is wound healing. Wounds are injuries to living tissue caused by a cut, blow, or other impact. There are numerous nanogels having different polymer compositions that have been reported to enhance the wound healing process, such as hyaluronan, poly-L-lysine, and berberine. When antimicrobial resistance is present, wound healing becomes a complicated process. Researchers are looking for novel alternative approaches, as foreign microorganisms in wounds are becoming resistant to antibiotics. Silver nanogels have been reported as a popular antimicrobial choice, as silver has been used as an antimicrobial throughout a prolonged period. Lignin-incorporated nanogels and lidocaine nanogels have also been reported as an antioxidant wound-dressing material that can aid in wound healing. In this review, we will summarize recent progress in biomedical applications for various nanogels, with a prime focus on cancer and wound healing. Full article

Carbon dioxide-based copolymers such as polypropylene carbonate (PPC) can offer the double environmental benefit of capturing CO₂ and replacing oil-based raw materials in the plastics industry with renewable ones. However, their production at an industrial level is still limited by the range of applications in which their physicochemical properties are competitive and ideally surpass those of fossil-based polymeric commodities. This work introduces PPC materials with high-stretch and self-healing properties that were prepared by copolymerization of CO₂ and propylene oxide using tailored Zn glutarate catalysts. The PPC materials were analyzed in terms of composition, molecular weight, thermal and mechanical behavior, particularly focusing on their tensile properties, strain recovery, creep response, and self-healing ability. All the prepared PPC materials showed good ductility and self-healing properties. The most promising ones achieved excellent and fast recovery of extremely high elongations (>700%), still reaching remarkable values (>600%) after proper self-healing. These high-stretch and self-healing PPC materials are completely amorphous, present good optical transparency, and can be processed using techniques normally used for other thermoplastics. Therefore, they are promising for a variety of applications, including shrink films and self-healing packaging, thus providing new, valuable perspectives for the industrialization of these CO₂-based polymers. Full article

Polymer nanocomposites (PNCs) are a versatile class of materials known for their enhanced mechanical, thermal, electrical, and barrier properties, with the latter referring to resistance against the permeation of gases and liquids. Achieving optimal nanoparticle dispersion within the polymer matrix is essential to fully realizing these advantages. This study investigates strategies for improving nanoparticle dispersion and examines the impact of controlled dispersion on the resulting nanocomposite properties. Various methods, including in situ polymerization, twin screw extrusion, sol–gel processes, nanoparticle surface modification, solution casting, and advanced compounding techniques such as additive manufacturing and self-healing composites were explored to enhance dispersion and improve the compatibility between nanoparticles and polymers. The synergy between improved dispersion and enhanced functionalities—such as increased mechanical strength, thermal stability, conductivity, and chemical resistance—makes these nanocomposites highly valuable for industrial applications in sectors such as the automotive, aerospace, electronics, pharmaceuticals, and packaging industries. The key recommendations based on our findings highlight how customized nanocomposites can address specific industrial challenges, fostering innovation in materials science and engineering. Full article

This study presents a novel self-healing mechanism for porcelain ceramics using UV-curable resin to address the inherent brittleness of ceramic materials. A biomimetic double-layered structure was designed, consisting of a high-density outer layer for mechanical strength and a highly porous inner layer for resin storage. The porous layer, achieved through nylon microparticle addition and subsequent volatilization during sintering, reached a porosity of 67%. As confirmed by FT-IR spectroscopy and EDS analysis, UV-curable acrylic resin was successfully incorporated into the porous structure. Three-point bending tests demonstrated efficient healing with a recovery rate of 56% after 5 min of UV irradiation. Both cured resin weight and post-healing bending strength increased logarithmically with UV irradiation time. The bending strength after healing was strongly dependent on the cured resin weight and polymerization depth within the specimen, as evidenced by the correlation between increased polymerization area and higher bending strength. This approach offers a promising solution for developing more reliable and durable ceramic materials, which will be particularly beneficial for aerospace and medical applications where maintenance cost reduction and extended product life are crucial. Full article

To address the issue of metal corrosion caused by microcracks in the coating on the steel structures of offshore drilling platforms, this study employs interfacial polymerization to prepare microcapsules with self-healing functionality for coatings. The microcapsules are fabricated through free radical polymerization between methyl methacrylate (MMA) and ammonium persulfate (APS), along with crosslinking reactions involving divinylbenzene (DVB). The particle size distribution and surface morphology of the microcapsules were optimized by adjusting process parameters using optical microscopy and scanning electron microscopy. Fourier-transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) were used to characterize the chemical structure and thermal stability of the microcapsules. The results show that when polyvinyl alcohol is used as the emulsifier, the oil–water ratio was 7.5:200, the amount of emulsifier was 1 wt%, the emulsification speed was 2500 r/min, the amount of initiator was 2 g, the core-to-wall ratio was 4:1, and the ambient temperature was 60 °C showed good sphericity, the microcapsules prepared under the optimized parameters exhibit good sphericity, a smooth surface, and an average particle size of 35.17 μm. They have a good core material encapsulation effect and thermal stability, which impart excellent self-healing properties to the epoxy coating. Such microcapsules have promising applications in mitigating the problem of metal corrosion of coatings due to microcracks and improving the service life and reliability of equipment. Full article

Self-healing composites are designed based on natural healing processes such as bone regeneration and blood coagulation. These composites have polymeric material containing covalent adaptable networks that rearrange their molecular structure when heated, thereby serving as a healing agent. The inclusion of the healing polymers into the principal matrix of the fiber-reinforced composites alters their off-axis properties. In addition, the healing agents tend to bleed out of the composite structures upon heating. It is, therefore, essential to characterize the extent of the changes in the off-axis properties of the self-healing composites. In this research work, three different configurations of self-healing composites are subjected to three-point bending tests, and their healing characteristics are studied using Acousto-Ultrasonic tests. Frequencies of the propagating stress waves in the AU tests are used to analyze the different conditions of the self-healing composites, such as virgin, damaged, damaged-partially healed, and damaged-fully healed. The results show that the AU test could potentially be used to evaluate the healing behavior of these fiber-reinforced self-healable composites. Full article

The preservation of interfacial integrity in esthetic dental restorations remains a critical challenge, with hybrid layer degradation being a primary factor in restoration failure. This degradation is driven by a combination of host-derived enzymatic activity, including matrix metalloproteinases (MMPs), bacterial proteases, and hydrolytic breakdown of the polymerized adhesive due to moisture exposure. This review examines the multifactorial mechanisms underlying hybrid layer degradation and presents current advancements in restorative materials aimed at counteracting these effects. Principal strategies include collagen preservation through the inhibition of enzymatic activity, the integration of antimicrobial agents to limit biofilm formation, and the use of ester-free, hydrolysis-resistant polymeric systems. Recent research highlights acrylamide-based adhesives, which exhibit enhanced resistance to acidic and enzymatic environments, as well as dual functionality in collagen stabilization. Furthermore, innovations in bioactive resins and self-healing materials present promising future directions for developing adhesives that actively contribute to long-term restoration stability. These findings underscore the importance of continuous advancements in adhesive technology to enhance the durability and clinical performance of dental restorations. Full article

Polyurethane (PU) plays a critical role in elastomers, adhesives, and self-healing materials. We selected the most commonly used aromatic isocyanates, 4,4′-methylene diphenyl diisocyanate (MDI) and tolylene-2,4-diisocyanate (TDI), and the most commonly used aliphatic isocyanates, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and dicyclohexylmethane-4,4′-diisocyanate (HMDI), as raw materials, combined with polytetramethylene ether glycol (PTMG) and 1,4-butanediol (BDO) to successfully synthesize five PU materials. The effects of isocyanate structure on polymerization rate, hydrogen bonding, thermal properties, phase separation, wettability, self-healing performance, adhesion, and mechanical properties were systematically investigated. The results show that isocyanates with higher symmetry facilitate hydrogen bonding, but excessive flexibility and crystallinity may inhibit its formation. MDI-based PU exhibits the highest hydrogen bonding index (HBI) of 4.10, along with the most distinct phase separation and the highest tensile strength of 23.4 MPa. HMDI-based PU demonstrates the best adhesion properties, with the highest lap shear strength of 7.9 MPa, and also exhibits excellent scratch healing ability. IPDI-based PU shows good self-healing performance, recovering 88.7% of its original tensile strength and 90.6% of its original lap shear strength after heating at 80 °C for 24 h. Furthermore, all the samples can be reprocessed by melt or solution methods, showing excellent recyclability. Full article

Polymeric composites are prone to undergoing damage, such as microcracks, during their operation, which can ultimately lead to catastrophic failure. To contradict such a problem, efforts have been carried out, by the scientific community, towards developing self-healing composites that, by mimicking biological systems, can autonomously and prematurely repair flaws, extending the durability and improving the security of materials. The present review explores the progress made in this area, focusing on extrinsic self-healing methods, as these can be employed to a variety of materials. Reservoir-based techniques, which resort to capsules, hollow fibers or microvascular networks, and thermoplastic-based ones are overviewed, prioritizing innovative approaches made in recent years. At last, promising practical applications for self-healing composites are highlighted and future challenges and opportunities are pointed out. Full article