Healing Performance Research Articles

Design and fabrication of pH-responsive skin scaffolds based on carrageenan and konjac glucomannan for accelerated wound healing.

The aim of this study was to utilize pH-responsive hydrogel skin scaffolds to achieve the sustained release of bioactive compounds (BCs) to promote wound healing. ZIF-8@flavanone nanoparticles were successfully synthesized through microfluidic channels and integrated into a hydrogel scaffold consisting of carrageenan (KC) and konjac glucomannan (KGM) to create a pH-responsive composite hydrogel scaffold. The unique pore structure of ZIF-8 efficiently loaded the active material, and the coordination bonds were disrupted in a slightly acidic environment, allowing the release of flavonoids. The natural macromolecular polysaccharides KC and KGM have good biocompatibility, and as a moist but not wet hydrogel scaffold substrate, they more closely resemble the growth environment of cells and are more favorable for wound healing. The hydrogel scaffolds developed in this study had a tensile strength of 1.15 MPa, an elongation at break of 320 %, good biocompatibility, a relative cell viability of 99.6 %, relative antimicrobial rate of 96.3 % (E. coli) and 95.8 % (S. aureus), respectively, and a release rate of 43.3 % at a pH of 5.0, and a wound closure rate at 15 d of 90.5 %, contributing to the improvement of wound healing performance and providing new possibilities for customized antimicrobial wound dressings.

Evaluation of Permeability Recovery in Precast Concrete with Hybrid Capsules Using Constant-Head Permeability Test as Smart Construction Material.

This study investigates the quality characteristics and healing performance of precast concrete incorporating self-healing technology, with the aim of supporting smart city implementation. To enhance the self-healing capabilities of concrete, hybrid self-healing capsules, combining solid capsules and liquid capsules, were utilized, and their applicability and practicality were assessed. The findings revealed that incorporating hybrid self-healing capsules into precast concrete resulted in a reduction in slump by up to 14% and air content by up to 9%. Furthermore, the addition of hybrid capsules led to a maximum reduction in compressive strength of 16% and flexural strength of 18% at 28 days, while demonstrating an increase in healing efficiency as the capsule content increased. The results also indicated that the use of hybrid capsules enhanced the healing efficiency by approximately 16%, 25%, and 32% for mixing ratios of 1%, 3%, and 5%, respectively, with the overall healing efficiency ranging between 75% and 90%. Additionally, the interaction between the hybrid capsules and natural healing mechanisms promoted crystal formation around cracks, thereby significantly improving the long-term durability of the concrete.

Top-down curing to construct self-retaining and moisture-pumping double-layered dressing with enhanced antibacterial, hemostatic, and wound healing performances.

Continuous microenvironment modulation is an ongoing challenge in wound dressing, which includes excessive exudate absorption, oxygen delivery, bacterial inhibition and angiogenesis. Herein, we developed an in situ construction strategy to fabricate a self-retaining double-layered wound dressing, where the top layer precursor was composed of Ca2+-containing polyvinyl butyral (PVB) solution dispersed with hydroxypropyl methylcellulose (HPMC) particles, and the bottom one consisted of sodium alginate (Alg) solution blended with Ag-doped mesoporous bioactive glass powders (Ag-MBG). When in use, both precursors were simultaneously squeezed out from the twin nozzles connected to the individual chambers of a twin-chambered syringe, whereby Ca2+ in the top layer rapidly migrated downwards to crosslink Alg in the bottom layer, leading to the formation of an Alg/Ag-MBG (AA) functional hydrogel for filling an irregular wound. Meanwhile, with the rapid evaporation of low-boiling solvents, the top layer changed into a PVB/HPMC (PH) membrane covering the AA hydrogel and adhering to the surrounding healthy skin to fix the dressing. Practically, HPMC particles in the top layer acting as "micropumps" could drain the wound exudate out, while Ag-MBG in the bottom layer endowed the dressing with anti-bacterial, hemostatic, and pro-healing functions. The integrally constructed PH-AA dressing achieved over 99% bacterial elimination against both E. coli and S. aureus. Biological assessments indicated that the double-layered dressing possessed excellent biocompatibility and enhanced wound healing, demonstrating a wound closure rate of >97% at day 15. This study provides a facile method to directly construct multi-layer dressings on wounds to meet various wound care requirements.

An Integrated Whole-Process Repair System with Programmed Regulation of Healing Performance Facilitates Urethral Wound Restoration and Scarless Reconstruction.

The harsh microenvironment of the urethral injury often carries high risks of early undesirable healing as well as late scar tissue formation. Indeed, the infection and inflammatory response in the early stages as well as blood vessel formation and tissue regeneration in the later stages fundamentally impact the outcomes of urethral wound healing. Innovatively, an integrated whole-process repair hydrogel (APF/C/L@dECM) is designed. After rigorous testing, it is found that hydrogels formed by hydrophobic association and double cross-linking of amide bonds can procedurally regulate wound healing in all phases to match the repair process. In rabbit models of urethral wound, APF/C/L@dECM hydrogel can achieve scarless reconstruction with significantly better results than other hydrogels. Noteworthily, multi-stage mechanistic explorations reveal the expression profiles of inflammation, vascularization, and extracellular matrix secretion-related genes in wound tissue at different times. In summary, this study develops an overall treatment for urethral injury through a whole-process repair system that promotes healthy healing of urethral wounds and prevents the formation of scar tissue.

Preparation and Wound Repair of Injectable and Self-Healing Benzaldehyde-Modified Konjac Glucomannan Oligosaccharide/Polyglutamic Acid/ε-Polylysine Hydrogel.

Oligosaccharides always have better water solubility, higher possibilities for modification, and unique biofunctions compared with polysaccharides, but they are rarely used as the matrix of a hydrogel. Here, we prepared a composite BKOS/HPGA/PL hydrogel (BKPP hydrogel) constructed by hydrazone/imine bonds between the aldehyde groups of benzaldehyde-modified konjac glucomannan oligosaccharide (BKOS) and the primary amino groups of both hydrazide-modified polyglutamic acid (HPGA) and ε-polylysine (ε-PL). The hydrogels had both injectable and self-healing properties. The gelation time reached 23 s when 2% of BKOS (DS = 21.7%), 10% HPGA (DS = 11.5%), and 10% ε-PL solutions were mixed in a volume ratio of 5:4.5:0.5. Besides high water-retention capability and good cytocompatibility, the hydrogel also maintained both the immunoactivities of BKOS and the antibacterial performances of ε-PL and HPGA, and thus exhibited good wound healing performance in the whole cortex wound repair process of rats, which might have potential for its biomedical application.

Asymmetric natural wound dressing based on porous chitosan-alginate hydrogel/electrospun PCL-silk sericin loaded by 10-HDA for skin wound healing: In vitro and in vivo studies

An asymmetric wound dressing introduced, inspired by the skin structure made of chitosan and alginate hydrogel as the bottom layer and electrospun PCL-silk sericin (PCL-SS) as the top layer. In addition, an anti-inflammatory, bactericidal and immunomodulatory substance, 10-hydroxydecanoic acid (10-HDA), known as queen bee acid, was loaded in inner layer. The wound dressing was thoroughly characterized and confirmed to meet the criteria of a standard wound dressing through in vitro and in vivo studies. Although the mesoporous hydrogel layer shows 175 % swelling after being immersed in PBS (pH = 7.4) for 60 min and 80 % degradation after 14 days, the top layer shows 28 % swelling and 19 % degradation in the same time intervals. The hydrogel layer supports rapid wound healing, while the top layer offers protection against infection and physical threats. The dressing demonstrated antibacterial properties and enhanced cell proliferation at 1 % 10-HDA. Finally, the wound healing performance of the complete dressing was investigated in vivo using wistar rat. Clinical and histopathological assessments, along with the analysis of biophysical parameters of the skin healing, confirm that wound dressing with 10-HDA significantly accelerates wound healing compared to control groups, without any inflammatory side effects.

Fabrication of Antibacterial and Flexible Hydrogels Based on Citric Acid Containing Tannic Acid for Wound Dressing

ABSTRACTIn this research, a biomonomer based on hydroxyethyl methacrylate, citric acid, and polyethylene glycol (HEMA‐CA‐PEG) was synthesized. After confirming the reaction through 1H‐NMR and FT‐IR tests and obtaining the intended monomer, a flexible hydrogel was synthesized as a wound dressing, and its mechanical properties were evaluated using tensile strength, DMTA, and rheometry tests. This synthesized hydrogel exhibited sufficient mechanical properties. To enhance the efficiency of this hydrogel wound dressing and its effectiveness in facilitating wound healing, tannic acid (TA), as an antibacterial and antioxidant substance, was incorporated into it. In the second phase, antibacterial activity and animal studies were conducted. The comparison of the CA–based hydrogel with and without TA demonstrated that the TA–containing hydrogel achieved more than 99.9% inhibition and elimination of bacteria. The use of CA–based hydrogel with TA shown in treating burns on the backs of rats caused the wound to close after 17 days, and hair growth was observed by the 21st day. This synthesized flexible hydrogel wound dressing, along with suitable mechanical properties, exceptional antibacterial activity, increased granulation tissue formation, re‐epithelialization, angiogenesis, and collagen deposition, showed good performance in wound healing.

Characterizing the Self‐Healing Asphalt Materials: A Neutron Imaging Study

Given the significant role of asphaltic pavement in surface transportation systems, even minor enhancements in asphalt materials hold the potential for cost savings and reduced environmental impacts. The healing properties of asphalt have drawn interest for sustainability, yet much remains unknown about the causes and influencing factors. To leverage self‐healing for extending pavement life, understanding the mechanisms and conditions that stimulate microcrack healing is essential. This study aims to investigate the dynamic progress of microcrack closure in asphalt mastics. The time‐series evolution of crack closure led by self‐healing is tracked by neutron computed tomography, with image processing facilitating volumetric analysis over a 7 h period. The study examines the healing process in mastic samples with three different sand filler contents (10, 20, and 30%). Results show that for all the investigated samples, the healing rate declines exponentially over time, with 100% recovery not achieved after 7 h at room temperature. Filler content‐influenced healing speed and 20% sand demonstrate the best performance. Meanwhile, the healing performance varies within the 10% and 30% groups, depending on initial crack size. Additionally, the study finds that initial crack size influences healing behavior in the samples.

High‐performance self‐healing epoxy by microencapsulated epoxy‐amine chemistry II: Performance of the system

AbstractThe self‐healing epoxy based on microencapsulated epoxy‐amine chemistry is a system with great potential for practical applications. Herein, microcapsules respectively containing epoxy and polyetheramine were fabricated using a microencapsulation technique via integrating electrospraying and interfacial polymerization (ES‐IP) and self‐healing epoxy based on the dual microcapsules were systematically investigated regarding the microcapsule dispersion, healing performance, failure mode, and mechanical properties. Microcapsules with different sizes were conveniently prepared by adjusting the injection rate. The microcapsules, regardless of the size, can be well dispersed in the epoxy matrix. The effects of the microcapsule size and concentration on the healing performance were studied. While full healing can be obtained for microcapsule >100 μm, high healing efficiency of about 90% and 70% can be achieved for microcapsules in 50 ~ 100 μm and ~ 50 μm, respectively. The healing performance decreases with the decreased microcapsule concentration. However, healing efficiency >70% can still be obtained when 5.0 wt% microcapsule of 50 ~ 100 μm were adopted. Mixed failure modes including adhesive failure, cohesive failure, and matrix failure, were observed, due to the good performance of the selected healant system. While the incorporated microcapsules, especially the small ones, evidently toughens the matrix, they deteriorate the tensile properties of the formulated self‐healing material.

High‐performance self‐healing epoxy by microencapsulated epoxy‐amine chemistry I: Properties of the adopted healant system

AbstractThe adopted healant has a significant impact on the final healing performance of self‐healing materials. Herein, the healant system, bisphenol‐F diglycidyl ether (BFDGE) and polytheramine JEFFAMINE T403, which possesses the capability of fully healing at room temperature (RT) for epoxy, was investigated in depth. The healing potential of this healant system and its healing benchmark after microencapsulation were systematically studied using a manual injecting method. It shows that the maximum and benchmark healing efficiencies respectively reach about 210% and 170% at RT for 48 h. The robustness of the cured healant was checked by studying the mechanical properties of BFDGE/T403. It verified that the tensile properties of the healant are stable after RT curing for 48 h. The curing degree of the healant was further characterized using differential scanning calorimetry by measuring the residual exotherm. It reaches 90% when the maximum healing performance is achieved and stabilizes at 95% thereafter. The results from the manually healing test, the tensile test, and the DSC test, are consistent with each other, which validate the robustness of BFDGE/T403 as healant for self‐healing epoxies.

Injectable Salecan/hyaluronic acid-based hydrogels with antibacterial, rapid self-healing, pH-responsive and controllable drug release capability for infected wound repair

Designing materials for wound dressings with superior therapeutic benefits, self-healing and injectable characteristics is important in clinical practice. Herein, a new self-healing injectable hydrogel was prepared via thermal treatment and dynamic Schiff base reaction by mixing oxidized hyaluronic acid (OHA) and hydrazided Salecan (Sal-ADH). The versatility of the wound dressing was confirmed by studying the inherent rheological properties, high swelling rate, sustained-release behavior of the drug, pH/hyaluronidase-dependent biodegradation, in vitro antimicrobial as well as in vivo wound healing performance. The presence of the antimicrobial drug polyhexamethylene biguanide (PHMB) conferred good antimicrobial properties to the Sal-ADH/OHA/PHMB (SOP) hydrogel, which could effectively prevent wound infection (the width of the inhibition circle of SOP-0.20 hydrogel was 4.97 mm, 5.93 mm for Staphylococcus aureus and Escherichia coli, respectively). The findings suggested that SOP hydrogel exhibited remarkable self-healing and injectability properties, as well as excellent hemostasis and biocompatibility. In vivo experiments indicated that the application of SOP hydrogels would obviously accelerate wound healing and attenuate the inflammatory response while increasing collagen deposition and angiogenesis. Altogether, antibacterial SOP hydrogels with moderate mechanical properties, pH-responsive release, excellent injectability, exceptional self-healing ability and anti-inflammatory effects could expand potential applications of injectable hydrogels in the biomedical field.

Amoxicillin-laded sodium alginate/cellulose nanocrystals/polyvinyl alcohol composite nanonetwork sponges with enhanced wound healing and antibacterial performance

Wound healing is a complex process and reuires a long repair process. Poor healing effect is normally a challenge for wound healing. Designing sponge dressings with drug-assisted therapy, good breathability, and multiple functional structures effectively promotes wound healing. In this work, a flexible amoxicillin-laded (AMX) sodium alginate (SA)/cellulose nanocrystals (CNCs)/ polyvinyl alcoho (PVA) (SA/CNCs/PVA-AMX, SCP-AMX) wound dressing was designed and built with an excellent porous structure, suitable porosity, and anti-bacterial properties for promoting wound tissue reparation. The porous structure of the wound dressing was fabricated by freeze-thawing cyclic and freeze-dried molding process. This wound dressing exhibited a 3D porous structure for soft-tissue-engineering application, including high porosity (84.2%), swelling ratio (1513%), tensile strength (1.79 MPA), and flexibility. With the inhibition zones of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) being 1.96 and4.58 cm, respectively, this wound dressing demonstrated good antibacterial activity against E. coli and S. aureus. More importantly, wound healing assay in vivo indicates that SCP-AMX could inhibit wound infection, promote collagen deposition, reduce inflammation, and accelerate granulation tissue and wound healing. Thus, the reported wounding dressings present excellent biocompatibility, high antibacterial activities, and excellent biosafety with great potential in wound healing applications.

Design of self-healing and anticorrosion epoxy coating with active multiple hydrogen bonds based on grafted polyetheramine

The healing of epoxy coatings in damaged areas significantly influences their service life and protection quality. Intrinsic self-healing coatings, which enable multiple healing cycles without the need for additional functional carriers, have emerged as a promising coating technology. Nevertheless, the cross-linked structure of thermoset epoxy coating system restricts the large-scale migration of molecular chains, posing a significant challenge to achieve intrinsic healing of resin without compromising its mechanical properties. In this study, we report a design scheme for epoxy coating with intrinsic self-healing properties based on active multiple hydrogen bonds. Grafting aminobenzothiazole at the end of polyetheramine D230 chain, the grafted polyetheramine (GD230) was synthesized and served as the auxiliary curing agent, whose accurate molecular structure has been confirmed by different characterizations. The self-healing coating with reversible dynamics network based on hydrogen bonds was prepared by crosslinking through epoxy resin and mixed curing agent of polyetheramine D230 and GD230. Various measurements have been adopted to evaluate the self healing and anticorrosion performance. Results showed that the functional coating with a ratio of 8:2 for D230 to GD230 has satisfied both performances on the steel substrate. After immersion in 3 wt% NaCl solution for 120 days, the impedance value of functional coating still remains about 1010 Ω cm2. After the coating was scratched and immersion for 96 h, the impedance value of functional coating increased by about two orders of magnitude compared to that in blank coating. Mechanical testing and theoretical calculations were used to support dynamic crosslinking model to reveal the self-healing mechanism.

Amine functionalized maleimide grafted MWCNT–CFRP hybrid composites interfacial/matrix healing and mechanical performance through thermally reversible cycloaddition

AbstractRestoration of the structural integrity of damaged CFRP composite through thermally reversible Diels–Alder bonds with the exact interfacial healing between matrix/fiber is extremely desirable for manufacturing of high‐performance self‐healing laminates. This article demonstrates the fabrication of amine‐functionalized maleimide‐grafted MWCNT (with different weight ratios 0.5 wt%, 1.0 wt%, and 1.5 wt%) reinforced thermally reversible self‐healing CFRP composite. The morphological changes, functional elements, elemental groups, and thermal degradation of functionalized‐MWCNTs were characterized by FESEM/HR‐TEM, FTIR, XRD, and TG‐DTA analysis. The results demonstrated that CFRP reinforced with silane/maleimide grafted MWCNT enhanced the dispersion, exhibited 82% healing efficiency and improvement in flexural strength‐67.11%, tensile strength‐64.75% concerning pure‐CFRP. FE‐SEM fractography of composites indicated that nanotube pullout was predominant failure‐criteria in CFRP‐pristine‐MWCNTs whereas strong interfacial adhesion dominated in CFRP‐maleimide‐MWCNTs. The purpose of this article is to investigate matrix/fiber/nanofillers interface healing properties of CFRP‐composite before and after damage. Furthermore, it is intended to reform structural integrity and examines average healing efficiency.Highlights Amine‐functionalized maleimide‐grafted MWCNT, CFRP composite fabrication. Characterized, morphological changes functional elements thermal degradation. Improvement in healing efficiency (82%), flexural strength‐(67.11%). The enthalpy of 0.5 wt% MWCNTBm enhanced to 10.91 J/g. Fractographic examinations show extensive intralaminar/interlaminar deformation.

Multiscale study on fatigue healing performance and molecular healing behavior of self-healing SBS modified bitumen

Self-healing polymer modified bitumen based on dynamic chemical bonds is a potential approach to improve the durability of bitumen pavement and save fossil energy. Herein, a novel self-healing SBS modified bitumen on the basis of dynamic disulfide bonds and hydrogen bonds was prepared. Firstly, an aliphatic disulfide (A-ALD) with disulfide bonds and hydrogen bonds was synthesized. Then A-ALD/SBS modified bitumen (A-ALD/SMB) was prepared by blending A-ALD and SBS modified bitumen. The chemical structure and microstructure of A-ALD/SMB were evaluated. In addition, the self-healing performance of A-ALD/SMB at the macroscopic scale and the self-healing behavior at the molecular scale were investigated by a combination of fatigue healing test and molecular dynamics (MD) simulation. The chemical structure analysis showed the formation of disulfide bonds and hydrogen bonds in A-ALD, and A-ALD was successfully attached to the CC bonds in SBS. Fluorescent images revealed that a better network structure appeared in A-ALD/SMB and formed a two-phase continuous morphology. The optimal dosage of A-ALD in SBS modified bitumen was 0.6 %. The fatigue healing test results indicated that A-ALD markedly enhanced the self-healing ability of SBS modified bitumen, and prolonging resting time and raising healing temperature can increase the self-healing performance of A-ALD/SMB. When the damage degree, healing temperature, and resting time were 30 %, 30 °C, and 60 min, respectively, the healing rate of A-ALD/SMB was 98.5 %, which was 30.2 % higher than SMB. The MD simulation results showed that the A-ALD enhanced the molecular diffusion capacity of SBS modified bitumen, and crack healing time of A-ALD/SMB was earlier than that of SMB under the same conditions. When the healing temperature was 40 °C, the time for the A-ALD/SMB and SMB molecular chain segments to start contacting and healing was 27 ps and 49 ps, respectively, which was improved by 44.9 % for A-ALD/SMB compared to SMB. Furthermore, the self-healing behavior of A-ALD/SMB at the molecular scale was consistent with the self-healing performance at the macroscopic scale under different healing temperatures and damage degrees. This study provided a theoretical basis for exploring the self-healing mechanism of SBS modified bitumen.

Polyvinyl alcohol-chitosan based oleanolic acid nanofibers against bacterial infection: In vitro studies and in vivo evaluation by optical and laser Doppler imaging modalities

The present work focuses on the fabrication of polyvinyl alcohol-chitosan-loaded oleanolic acid-nanofibers (PVA-CS-OLA-NFs) for bacterial infection. The prepared PVA-CS-OLA-NFs were characterized for contact angle, SEM, AFM, XRD, FTIR, and TGA. The solid-state characterization and in vitro performance evaluation of nanofibers reveal consistent interconnection and diameters ranging from 102 ± 9.5 to 386 ± 11.6 nm. The nanofibers have a flat surface topography and exhibit efficient drug entrapment. Moreover, the in vitro release profile of PVA-CS-OLA-NFs was found to be 51.82 ± 1.49 % at 24 h. Furthermore, the hemocompatibility study showed that the developed PVA-CS-OLA-NFs are non-hemolytic to human blood. The PVA-CS-OLA-NFs demonstrate remarkable antibacterial capabilities, as evidenced by their MBC and MIC values, which range from 128 and 32 μg/mL, against the strains of S. aureus. The in-vivo fluorescence optical imaging showed the sustained PVA-CS-OLA-NFs release at the wound site infected with S. aureus for a longer duration of time. Moreover, the PVA-CS-OLA-NFs showed superior wound healing performance against S. aureus infected wounds compared to the marketed formulation. Further, the laser Doppler imaging system improved oxygen saturation, blood supply, and wound healing by providing real-time blood flow and oxygen saturation information.

Strong and Healable Elastomers with Photothermal-Stimulus Dynamic Nanonetworks Enabled by Subnano Ultrafine MoO3-x Nanowires.

One-dimensional nanomaterials have become one of the most available nanoreinforcing agents for developing next-generation high-performance functional self-healing composites owing to their unique structural characteristics and surface electron structure. However, nanoscale control, structural regulation, and crystal growth are still enormous challenges in the synthesis of specific one-dimensional nanomaterials. Here, oxygen-defective MoO3-x nanowires with abundant surface dynamic bonding were successfully synthesized as novel nanofillers and photothermal response agents combined with a polyurethane matrix to construct composite elastomers, thus achieving mechanically enhanced and self-healing properties. Benefiting from the surface plasmon resonance of the MoO3-x nanowires and interfacial multiple dynamic bonding interactions, the composite elastomers demonstrated strong mechanical performance (with a strength of 31.45 MPa and elongation of 1167.73%) and ultrafast photothermal toughness self-healing performance (20 s and an efficiency of 94.34%). The introduction of MoO3-x nanowires allows the construction of unique three-dimensional cross-linked nanonetworks that can move and regulate interfacial dynamic interactions under 808 nm infrared laser stimulation, resulting in controlled mechanical and healing performance. Therefore, such special elastomers with strong photothermal responses and mechanical properties are expected to be useful in next-generation biological antibacterial materials, wearable devices, and artificial muscles.

A polyurea capturing both high strength and rapid self-healing tailored for intelligent barrier anti-corrosion system

The long-term repair of organic coatings in underwater environments is hindered by microcracks and their poor healing performance. In this study, a high-strength and rapidly self-healing polyurea (PU3) coating that combines asymmetric dense stacking of supramolecular units with mismatched rigid and flexible polymer chains was developed. By exploiting the interaction between a 2D sheet-like Ti3C2TX MXene and finely tailored hydrogen-bonded structures of PU3, a smart biomimetic anticorrosion composite coating (PU3-1.0 wt% MXene) was produced. This coating achieved rapid (15 s), specific, and repeatable in situ repair underwater when exposed to near infrared laser light. Electrochemical tests confirmed its excellent anticorrosion capability.

Study on the Factors Affecting the Self-Healing Performance of Graphene-Modified Asphalt Based on Molecular Dynamics Simulation.

To comprehensively understand the impact of various environmental factors on the self-healing process of graphene-modified asphalt, this study employs molecular dynamics simulation methods to investigate the effects of aging degree (unaged, short-term aged, long-term aged), asphalt type (base asphalt, graphene-modified asphalt), healing temperature (20 °C, 25 °C, 30 °C), and damage degree (5 Å, 10 Å, 15 Å) on the self-healing performance of asphalt. The validity of the established asphalt molecular models was verified based on four physical quantities: density, radial distribution function analysis, glass transition temperature, and cohesive energy density. The simulated healing time for the asphalt crack model was set to 200 ps. The following conclusions were drawn based on the changes in density, mean square displacement, and diffusion coefficient during the simulated healing process under different influencing factors: Dehydrogenation and oxidation of asphalt molecules during the aging process hinder molecular migration within the asphalt crack model, resulting in poorer self-healing performance. As the service life increases, the decline in the healing performance of graphene-modified asphalt is slower than that of base asphalt, indicating that graphene-modified asphalt has stronger anti-aging properties. When the vacuum layer in the asphalt crack model is small, the changes in the diffusion coefficient are less pronounced. As the crack width increases, the influence of various factors on the diffusion coefficient of the asphalt crack model becomes more significant. When the crack width is large, the self-healing effect of asphalt is more dependent on these influencing factors. Damage degree and oxidative aging have a more significant impact on the healing ability of graphene-modified asphalt than healing temperature.

Self‐healing reversible network from furfuryl‐functionalized copoly(triazine‐r‐polypropylene glycol‐r‐polydimethylsiloxane)

AbstractNew shape‐memory networks composed of both reversible Diels–Alder covalent crosslinks and the hydrogen and π–π stacking bonds of triazine functional groups, with self‐healing properties as a result of the reversibility of these dynamic bonds were achieved from a furfuryl‐functionalized copoly(triazine‐r‐polypropylene glycol‐r‐polydimethylsiloxane), crosslinked with a maleimide end‐capped polycaprolactone and a long polycaprolactone‐based chain extender. The presence of multiple dynamic bonds, including the Diels–Alder and triazine‐derived π–π stacking and H‐bond interactions as well as the enhanced network mobility arising from polypropylene glycol, polydimethylsiloxane and polycaprolactone segments upon triggering the shape memory effect resulted in a material with high toughness (~200 MPa J−1) and efficient healing ability (with a recoveries of tensile strength and toughness after being cut and healed of 87% and 94%, respectively).Highlights Furfuryl dichlorotriazine was coupled with PPG and PDMS forming a copolymer. The copolymer was crosslinked with PCL‐dimaleimide and PCL‐difuran extender. Multiple dynamic bonds (Diels–Alder, π–π stacking and H‐bond) were present. The network showed high toughness and good healing performance.