Cross-linked Composites Research Articles

Fabrication of high performance polypropylene based blends from ethylene vinyl acetate-based sole waste via solid-state shear Co-milling

Ethylene vinyl acetate copolymer (EVA) foam products with cross-linked structure are now widely used in the fields of functional footwear. However, due to their cross-linked structure and complex composition, they are quite difficult to be recovered in large scale after disposal, causing serious environmental pollution. Based on our self-designed solid-state shear milling (S3M) equipment, a novel co-milling technology was established to recycle ethylene vinyl acetate-based sole waste (ESW) and reuse it to strengthen and toughen polypropylene (PP). The effects of co-milling on PP/ESW powders as well as blends were studied, and the results showed that the existence of PP promoted the solid pulverization of ESW, so formed the powders with smaller size and wider distribution. Ascribing to the partial de-crosslinking of ESW during co-milling process, the contact area and the molecular entanglements at their interfaces increased, effectively improving the compatibility between PP and ESW. In this way, the simultaneous enhancement and toughening of ESW on PP were achieved. After co-milling, ESW phase in blends significantly decreased and no visible phase interface was observed. With 20 co-milling cycles, the tensile strength and impact toughness of PP/20 wt% ESW blend respectively increased from 21.9 MPa to 3.79 kJ/m2 to 25.4 MPa and 5.83 kJ/m2, both higher than most other similar PP based materials. This work provides a new strategy for high-quality and efficient recycling of ESW in large scale, and fabrication of high-performance PP based materials.

Solvent-free preparation of carbon fiber reinforced dynamically cross-linked vanillin-based polyurethane composites with excellent self-healing and closed-loop recycling performance

Disposing of the wastes generated from the carbon fiber reinforced polymer (CFRP) composite materials after service failure has attracted great attention in recent years. CFRP composites prepared with dynamically covalent cross-linking polymers as matrix resins possess excellent self-healing and recyclability performance, providing an efficient solution to overcome this challenge. However, most of the dynamic cross-linking resins are typically made by high-cost petroleum-derived compounds with extensive use of organic solvents and environmentally unfriendly catalysts. Herein, catalyst-free self-healing and recyclable vanillin-based polyurethanes (V-PUs) via dynamic phenol-carbamate bonds were synthesized by a one-step solvent-free method with a biodegradable PCL as soft segment and biobased vanillin derivative as the chain extender. The optimized V-PUs exhibit Young's modulus of 1.92 GPa, stress at break of 64.98 MPa, glass transition temperature of 95 °C, and over 90 % self-healing and reprocessing efficiency. This excellent self-healing and reprocessing performance can be successfully transferred to the CFRP composite materials fabricated with the V-PUs as matrix resins by hand paste-vacuum bag pressing method. The interlayer shear strength (ILSS) of the composite material is 41 MPa, and the healing efficiency determined by ILSS reaches 85.34 %. Closed-loop recovery of the carbon fiber and matrix resin from the CFRP composite is realized through the solvent dissolution approach due to the dynamic character of the phenol-carbamate bonds, which is of great significance for the development of green economy and sustainable society.

A strategy for the efficient removal of acidic and basic dyes in wastewater by organophilic magadiite@alginate beads: Box-Behnken Design optimization

In this study, four adsorbents were developed: layered silicate magadiite material (mag), Hexadecyltrimethylammonium intercalated magadiite (HDTMA@mag), a cross-linked composite of sodium alginate and magadiite (ALG@mag) and a cross-linked composite of sodium alginate and HDTMA@magadiite (ALG@HDTMA@mag). The adsorbents were evaluated for their effectiveness in removing of Methylene Blue (MB) and Eriochrome Black T (EBT) dyes. The prepared adsorbents were characterized using SEM, XRD, FTIR, and zeta potential measurements. Kinetic modeling results indicated that both film diffusion and intraparticle diffusion are useful as rate-determining processes in adsorption for all adsorbents. For both dyes, the Langmuir isotherm model provided a good correlation with the adsorption equilibrium data. ANOVA analysis for the best adsorbent (ALG@HDTMA@mag beads) revealed that MB removal was significantly influenced by the positive individual effects of contact time and ALG@HDTMA@mag dose. However, the individual effect of MB concentration exhibited an antagonistic effect throughout the adsorption process. The optimal parameters for achieving an adsorption capacity of 118.54 mg/g were a dye concentration of 60 ppm, a contact period of 1800 min, and an ALG@HDTMA@mag dose of 50 mg.

Optimization of anionic dye removal using cross-linked chitosan composite as eco-friendly bio-adsorbent

The environmental impact of wastewater discharged from the textile dyeing industry has a significant challenge and influence on aquatic ecosystems and human health if not properly managed. This study aimed to develop a novel cross-linked chitosan composite, denoted as chitosan/fly ash/polyvinyl alcohol (Ch/FA/PVA), as a bio-adsorbent for removing Congo Red (CR) textile dye from industrial wastewater. The synthesis involved the incorporation of FA into the chitosan matrix at various ratios to optimize the process. A specifically tailored composite, Ch/FA0.75/PVA, exhibited superior performance with a remarkable 99.7% CR removal under optimum conditions: adsorbent dose (0.9 g/l), contact time (50 min), and dye concentration (40 mg/l). The characterization of Ch/FA0.75/PVA through SEM–EDX, BET, FTIR, and pHzpc confirmed its suitability for adsorption. Employing Box–Behnken design and analysis of variance (ANOVA) facilitated the optimization of key adsorption variables. The Freundlich model described the adsorption equilibrium, indicating a maximum adsorption capacity of 263.15 mg/g for CR dye. The pseudo-second-order model demonstrated favorable kinetics. The study was scaled up to the practical application of Ch/FA0.75/PVA in a pilot plant for industrial wastewater treatment, revealing substantial removal percentages for dye, color, COD, BOD5 and TDS. This comprehensive approach highlights the promising efficacy of Ch/FA0.75/PVA in addressing environmental concerns associated with textile dye wastewater.

Design of degradable hybrid dual-crosslinked polymer for high-efficiency profile control in high temperature reservoirs

Profile control and water plugging are key technologies to enhance oil and gas recovery. Traditional plugging materials, due to short gelation time, low mechanical strength, and difficulty in balancing plugging and protection, thus limiting application in high temperature reservoirs. Herein, a degradable hybrid dual-crosslinked polymer was prepared by employing a copolymerization - dual-grafting and physical adsorption design strategy. The dual-crosslinked process and reaction mechanism were analyzed using infrared spectroscopy and differential scanning calorimetry. The mechanical properties, water dilution resistance, aging stability and degradability of the dual cross-linked composite were also investigated. The solvation forces enable silica particles to exhibit excellent suspension stability in a PEG solvent. The temperature ranges from normal atmospheric temperature (20 °C) to reservoir temperature (140 °C), with the apparent viscosity falling within the range of 10–1200 mPa·s, meeting the requirements for mixing and injection. The combination of free radical copolymerization and click reaction is utilized to control the gelation time (2–10 h) in high temperature environment (140 °C), which is favorable for regulating the action position of the plugging agent in the reservoir. The cured material exhibits excellent mechanical strength owing to the presence of dual-crosslinking and inorganic hybridization, with a compressive strength of 0.221 MPa and a peak strain of 55.3 %. Furthermore, this composite material undergoes hydrolysis through an addition-elimination reaction, transitioning from a solid to a liquid state within 24 h, thereby aiding in the restoration of productivity in the temporarily shielded target layer. Compared to traditional materials, this dual-crosslinked composite system have the advantages of controllable gelation time, high mechanical strength, aging resistance, and degradability, making it suitable for profile control in high temperature reservoirs (140 ℃, 21.81×104 mg/L).

Effect of Chemical Composition of Metal-Organic Crosslinker on the Properties of Fracturing Fluid in High-Temperature Reservoir.

To investigate the effect of the chemical composition of a metal-organic crosslinker on the performances of fracturing fluid in high-temperature conditions, four zirconium (Zr) crosslinkers and one aluminum-zirconium (Al-Zr) crosslinker with a polyacrylamide were used. The crosslinkers possessed the same Zr concentration, but they differed in component amounts and the order of the addition of the crosslinker components, leading to different chemical compositions in the crosslinkers. The fracturing fluids prepared by different tested crosslinkers were compared in terms of properties of rheological behavior, sand-carrying ability, microstructure, and gel breaking characteristics. The results showed that the fracturing fluids prepared by zirconium lactic acid, ethanediamine, and sorbitol crosslinkers offered the slowest viscosity development and highest final viscosity compared to the zirconium lactic acid crosslinker and the zirconium lactic acid and ethanediamine crosslinker. The zirconium sorbitol, lactic acid, and ethanediamine crosslinker exhibited a faster crosslinking rate and a higher final viscosity than the zirconium lactic acid, ethanediamine, and sorbitol crosslinker; the crosslinker showed crosslinking density and crosslinking reactivity, resulting in more crosslinking sites and a higher strength in the fracturing fluid. The Al-Zr-based crosslinker possessed better properties in temperature and shear resistance, viscoelasticity, shear recovery, and sand-carrying ability than the Zr-based crosslinker due to the synergistic crosslinking effect of aluminum and zirconium ions. The tertiary release gelation mechanism of the Al-Zr-based fracturing fluid achieved a temperature resistance performance in the form of continuous crosslinking, avoiding the excessive crosslinking dehydration and reducing viscosity loss caused by early shear damage. These results indicated that the chemical compositions of metal-organic crosslinkers were important factors in determining the properties of fracturing fluids. Therefore, the appropriate type of crosslinker could save costs without adding the additional components required for high-temperature reservoirs.

Design a cross-linked film based on cellulose nanocrystals doping for enhancing the interfacial performance and desensitization of CL-20

Despite the extensive researches on CL-20 crystals, the mechanical safety issues and process problems of CL-20 applications have not been studied in-depth. Herein, the cellulose nanocrystals (CNC) was doped in microcrystalline wax (MW), oxidized microcrystalline wax (OMW) and hydrogel (PPC) to design and fabricate the cross-linked CL-20 composites by simple water-suspension melting and freeze-drying methods. The composites were characterized by SEM, XPS, TG-DSC, XRD, mechanical sensitivity device and inclined chute tester. It is found that the CNC@OMW composite film exhibits excellent coating effect (99.96%) on CL-20 due to the cross-linking results. The Ea of CL-20 is increased from 190.92 to 388.71 kJ/mol under the synergistic effect of the excellent compatibility between components and the compact coating structure of CNC@OMW. Additionally, the film enhances the Tp0 of CL-20 from 218.15 to 222.66 ℃ and Tb from 220.27 to 223.73 ℃, respectively. While, the PPC@CNC only promoted Ea, Tp0 and Tb of CL-20–292.89.71 kJ/mol, 224.22 ℃ and 225.66 ℃, respectively. Besides, the XRD results confirms that three composite films dose not cause a transformation of the ε-CL-20 crystal phase. Most importantly, the cross-linked film brings mechanical sensitivity of CL-20 from 60 N and 3.5 J to a level of over 360 N and 10.4 J, comparable to WO3/Al nanothermite with 5 wt% polyaniline (360 N) and composite with 95 wt% LLM-105 and 5 wt% ternary (11–12 J). This improvement enables the composite explosives to be handled using standard procedures. Furthermore, the ability of the particles to accumulate electrostatic charge after cross-linking coating is significantly reduced, and PVC is more suitable as the contact material of CL-20 and composite particles than copper for use in the transportation and packaging. These findings can serve as a reference for wide application of CL-20.

Citric Acid Cross-Linked Gelatin-Based Composites with Improved Microhardness.

The aim of this study is to investigate the influence of cross-linking and reinforcements in gelatin on the physico-mechanical properties of obtained composites. The gelatin-based composites cross-linked with citric acid (CA) were prepared: gelatin type B (GB) and β-tricalcium phosphate (β-TCP) and novel hybrid composite GB with β-TCP and hydroxyapatite (HAp) particles, and their structure, thermal, and mechanical properties were compared with pure gelatin B samples. FTIR analysis revealed that no chemical interaction between the reinforcements and gelatin matrix was established during the processing of hybrid composites by the solution casting method, proving the particles had no influence on GB cross-linking. The morphological investigation of hybrid composites revealed that cross-linking with CA improved the dispersion of particles, which further led to an increase in mechanical performance. The microindentation test showed that the hardness value was increased by up to 449%, which shows the high potential of β-TCP and HAp particle reinforcement combined with CA as a cross-linking agent. Furthermore, the reduced modulus of elasticity was increased by up to 288%. Results of the MTT assay on L929 cells have revealed that the hybrid composite GB-TCP-HA-CA was not cytotoxic. These results showed that GB cross-linked with CA and reinforced with different calcium phosphates presents a valuable novel material with potential applications in dentistry.

Bioactive Nanofiber-Hydrogel Composite Regulates Regenerative Microenvironment for Skeletal Muscle Regeneration after Volumetric Muscle Loss.

Volumetric muscle loss (VML) is a severe form of muscle trauma that exceeds the regenerative capacity of skeletal muscle tissue, leading to substantial functional impairment. The abnormal immune response and excessive reactive oxygen species (ROS) accumulation hinder muscle regeneration following VML. Here, an interfacial cross-linked hydrogel-poly(ε-caprolactone) nanofiber composite, that incorporates both biophysical and biochemical cues to modulate the immune and ROS microenvironment for enhanced VML repair, is engineered. The interfacial cross-linking is achieved through a Michael addition between catechol and thiol groups. The resultant composite exhibits enhanced mechanical strength without sacrificing porosity. Moreover, it mitigates oxidative stress and promotes macrophage polarization toward a pro-regenerative phenotype, both in vitro and in a mouse VML model. 4 weeks post-implantation, mice implanted with the composite show improved grip strength and walking performance, along with increased muscle fiber diameter, enhanced angiogenesis, and more nerve innervation compared to control mice. Collectively, these results suggest that the interfacial cross-linked nanofiber-hydrogel composite could serve as a cell-free and drug-free strategy for augmenting muscle regeneration by modulating the oxidative stress and immune microenvironment at the VML site.

Reprocessable and self-healable boronic-ester based poly(styrene-b-isoprene-b-styrene) vitrimeric elastomer with improved thermo-mechanical property and adhesive performance

It is fascinating to develop vitrimeric elastomers with excellent processability and improved physical properties through incorporating reversible covalent bonds into traditional thermoplastic elastomers. In this work, a poly(styrene-b-isoprene-b-styrene) (SIS) thermoplastic elastomer was selected as the base elastomer and converted into vitrimer through peroxide-induced crosslinking reaction with di-vinyl-terminated boronic ester crosslinker. Kissinger model predicts that the activation energy of vitrimer crosslinking process is slightly higher than that of chemical crosslinking process. The peroxide content was adjusted to tune the composition of permanent chemical crosslinks and dynamic chemical crosslinks. In this way, SIS vitrimer elastomer with tailored multiple network structure was successfully prepared. The stress relaxation behavior of all SIS-BE samples shows Arrhenius-type temperature-dependency and the bond-exchange activation energy (Ea) of SIS-D0.5-B5 sample was estimated as 44.14 kJ/mol. SIS vitrimer elastomer shows improved creep-resistance, comparative mechanical strength and elastic recovery in relative to crosslinked SIS elastomer while maintaining good reprocessbility and self-healing efficiency. Additionally, SIS vitrimeric elastomer shows an increased lap-shear strength from 0.53 MPa to 1.02 MPa with the increase of DCP content. Therefore, we have demonstrated the potential for industrial-scale production of SIS vitrimer elastomer and its applications as reprocessable and healable adhesives.

Exploring Extracellular Matrix Crosslinking as a Therapeutic Approach to Fibrosis.

The extracellular matrix (ECM) provides structural support for tissues and regulatory signals for resident cells. ECM requires a careful balance between protein accumulation and degradation for homeostasis. Disruption of this balance can lead to pathological processes such as fibrosis in organs across the body. Post-translational crosslinking modifications to ECM proteins such as collagens alter ECM structure and function. Dysregulation of crosslinking enzymes as well as changes in crosslinking composition are prevalent in fibrosis. Because of the crucial roles these ECM crosslinking pathways play in disease, the enzymes that govern crosslinking events are being explored as therapeutic targets for fibrosis. Here, we review in depth the molecular mechanisms underlying ECM crosslinking, how ECM crosslinking contributes to fibrosis, and the therapeutic strategies being explored to target ECM crosslinking in fibrosis to restore normal tissue structure and function.

Sustainable solutions: Transforming waste shield tunnelling soil into geopolymer-based underwater backfills

Waste shield tunnelling soil is often utilized as backfill materials in engineering practice. However, traditional backfill materials exhibit poor backfilling performance in underwater condition, which is even more commonly encountered in backfilling projects. In response to this issue, this study introduces a geopolymer-based underwater controlled low-strength material (UWCLSM) that utilizes recycled waste shield tunnelling soil and granulated blast furnace slag (GBFS). The UWCLSM demonstrates promising underwater performance, making it a viable candidate as a new underwater construction material. Key characteristics include a flowability exceeding 280 mm, unconfined compressive strength ranging from 1 to 2 MPa, high resistance to water erosion with an anti-washout strength ratio consistently above 80%, and a permeability coefficient lower than 10−7 cm/s. The addition of anti-washout admixtures (AWA) plays a pivotal role in enhancing the UWCLSM's underwater performance. Polyacrylamide (PAM) effectively attracts soil particles, depolymerized GBFS monomers, and cement particles, reducing dispersion in water. An optimal amount of PAM forms cross-linked composites with GBFS and soil particles, resulting in slight improvements in UCS, shear strength, and impermeability. The combination of PAM and carboxymethyl cellulose enhances UWCLSM's cohesion and viscosity, optimizing its suitability for underwater applications. Moreover, the UWCLSM's cost, CO2 emissions, and energy consumption are only 55.6%, 16.7%, and 16.1% of those associated with traditional materials, contributing to sustainability and offering significant environmental benefits, respectively.

PVA-TiO2 Nanocomposite Hydrogel as Immobilization Carrier for Gas-to-Liquid Wastewater Treatment

This study investigates the development of polyvinyl alcohol (PVA) gel matrices for biomass immobilization in wastewater treatment. The PVA hydrogels were prepared through a freezing–thawing (F-T) cross-linking process and reinforced with high surface area nanoparticles to improve their mechanical stability and porosity. The PVA/nanocomposite hydrogels were prepared using two different nanoparticle materials: iron oxide (Fe3O2) and titanium oxide (TiO2). The effects of the metal oxide nanoparticle type and content on the pore structure, hydrogel bonding, and mechanical and viscoelastic properties of the cross-linked hydrogel composites were investigated. The most durable PVA/nanoparticles matrix was then tested in the bioreactor for the biological treatment of wastewater. Morphological analysis showed that the reinforcement of PVA gel with Fe2O3 and TiO2 nanoparticles resulted in a compact nanocomposite hydrogel with regular pore distribution. The FTIR analysis highlighted the formation of bonds between nanoparticles and hydrogel, which caused more interaction within the polymeric matrix. Furthermore, the mechanical strength and Young’s modulus of the hydrogel composites were found to depend on the type and content of the nanoparticles. The most remarkable improvement in the mechanical strength of the PVA/nanoparticles composites was obtained by incorporating 0.1 wt% TiO2 and 1.0 wt% Fe2O3 nanoparticles. However, TiO2 showed more influence on the mechanical strength, with more than 900% improvement in Young’s modulus for TiO2-reinforced PVA hydrogel. Furthermore, incorporating TiO2 nanoparticles enhanced hydrogel stability but did not affect the biodegradation of organic pollutants in wastewater. These results suggest that the PVA-TiO2 hydrogel has the potential to be used as an effective carrier for biomass immobilization and wastewater treatment.

Role of additive size in the segmental dynamics and mechanical properties of cross-linked polymers.

Thermoset materials often involve the addition of molecular and nanoparticle additives to alter various chemo-physical properties of importance in their ultimate applications. The resulting compositional heterogeneities can lead to either enhancement or degradation of thermoset properties, depending on the additive chemical structure and concentration. We tentatively explore this complex physical phenomenon through the consideration of a model polymeric additive to our coarse-grained (CG) thermoset investigated in previous works by simply varying the size of additive segments compared to those of polymer melt. We find that the additive modified thermoset material becomes chemically heterogeneous from additive aggregation when the additive segments become much smaller than those of the thermoset molecules, and a clear evidence is observed in the spatial distribution of local molecular stiffness estimated from Debye-Waller factor 〈u2〉. Despite the non-monotonic variation trends observed in dynamical and mechanical properties with decreasing additive segmental size, both the structural relaxation time and moduli (i.e., shear modulus and bulk modulus) exhibit scaling laws with 〈u2〉. The present work highlights the complex role of additive size played in the dynamical and mechanical properties of thermoset polymers, which should provide a better understanding for the glass formation process of cross-linked polymer composites.

Tailoring dual cross-linked polymer-ionic liquid composites by blending co-crystallizable polymers for stretchable electronics

A dual cross-linked polymer-ionic liquid composite exhibits self-healing capabilities and is ideal for wearable strain sensor applications.

Enhanced design of dual dynamic cross-linked rubber composites: Achieving self-healing and recyclability through imine and metal-ligand bonding

The quest to confer self-healing and recyclable properties to conventional rubber is a prominent research area in the rubber industry. This study presents the novel construction of a self-healing and recyclable rubber composite by employing imine bond and Cu2+-imine cross-linking the polybutadiene rubber matrix and Cu2+-imidazole groups cross-linking at the silica-rubber interface. The introduction of imine bonded cross-linked imparts high elasticity to the rubber, while the Cu2+-imidazole complex serves as a bridge, enhancing the interfacial interaction between the silica and rubber matrix. The Cu2+-N (Cu2+-imidazole and Cu2+-imine) complexes not only improves silica dispersion but also acts as a sacrificial unit, thereby enhancing the mechanical properties of the rubber composites. The addition of 0.2 mmol anhydrous copper (II) chloride (CuCl2) results in a significant increase in tensile strength and Young's modulus of the samples (1.04 and 3.91 MPa), with improvements of 181 % and 407 %, respectively, compared to the pure samples. Additionally, the highly dynamic nature of the imine bond and the Cu2+-N (Cu2+-imidazole and Cu2+-imine) complexes imparts excellent self-healing and recyclable properties to the material, exhibiting repair efficiency and recycling recovery of up to 90 % (tensile strength). Therefore, this work opens a new avenue for the design and development of self-healing, recyclable rubber composites.

Synthesis of poly(propylene fumarate)-polyurethane urea composite with kartogenin-modified chitosan for cartilage tissue engineering

In this research, we explored the development of a cross-linked polymer composite, poly(propylene fumarate)-polyurethane urea (PPFUU), designed to foster the differentiation of human adipose-derived mesenchymal stem cells (hADMSCs) into chondrocytes. PPFUU was synthesized using PPF-diol, 1,6-diisocyanatohexane, and putrescin, which served as the soft section, hard section, and chain extender, respectively. To optimize its characteristics, PPFUU was integrated with a chitosan-kartogenin conjugate (CS-KGN) at varying weight fractions. The blend underwent chemical crosslinking via free radical polymerization, with benzoyl peroxide as the initiator and N-vinyl pyrrolidinone as the crosslinking agent. The resulting composites were rigorously analyzed for different properties, including thermal behavior, hydrophilicity, compressive strength, biocompatibility, and more. Significantly, the introduction of CS enhanced glycosaminoglycan formation. Furthermore, hADMSCs, when cultured in chondrogenic media on the CS-KGN-integrated PPFUU composite, exhibited upregulated SOX9 and aggrecan expression. Based on these in vitro results, the CS-KGN-conjugated PPFUU composite presents a promising avenue for cartilage tissue regeneration.

Shape memory effect in cross-linked polyethylene matrix composites: the effect of the type of reinforcing fiber

The recovery stress of shape-memory polymers is often low; therefore their field of application is limited. In this study, we compared the effects of different fiber reinforcements on the shape memory characteristics of cross-linked polyethylene (X-PE) matrix. We used fiber reinforcement to increase the recovery stress of the shape memory polymer and compared the results of different fiber reinforcements to find the ones that confer the best shape memory properties. We investigated glass, carbon, Kevlar®, and Dyneema® fibers to find the fibers that increase the recovery stress of the composites most. The deformed shape was created by three-point bending, and then heat-activated shape recovery was examined. All reinforcements increased the recovery stress and decreased the shape fixity ratio and the shape recovery ratio. The samples had similar characteristics, except for the low recovery stress Kevlar® fibers and the low recovery ratio of the composite reinforced with glass fibers. With the polyethylene Dyneema® fibers, the composite was self-reinforced and did very well by all metrics. They increased the maximum recovery stress from 0.3 to 2.4 MPa, through having excellent adhesion to the matrix and high strength in their own right. Our research proved that self-reinforced composites could measure up to conventional composites in shape memory applications. Aside from the Dyneema® fibers carbon fibers work best in the X-PE matrix, and should be the preferred conventional reinforcement materials.

Three-dimensional graphene cross-linked carbon nanotube doping as cathode for aqueous zinc ion batteries

Aqueous zinc ion batteries (ZIBs) are becoming increasingly popular in the field of energy storage due to their high safety and environmental friendliness. This study comparatively investigated the electrochemical performance of β-MnO2 as a cathode for ZIBs after doping with different ratios of three-dimensional graphene (3D-GPE)/carbon nanotube (CNT) cross-linked composite materials with ball milling. The results show that 3D-GPE/CNT cross-linked composite has an effect on β-MnO2 microstructure and particle morphology. The cathode made of β-MnO2/(3D-GPE/CNT) with a mass ratio of 9:1 has a very high reversible capacity of 1078.93 mAh/g at a current density of 10 mA g−1, which is about 2.24 and 1.87 times the other two ratio materials (18:1 and 12:1), respectively. After 100 cycles, the median voltage difference of the β-MnO2/(3D-GPE/CNT) mass ratio 9:1 specimen battery increased. The higher the median voltage, the higher the energy of the battery. The improvement of cathode performance is directly related to the micro-state, such as the three-dimensional frameworks and carbon nanotube structures of 3D-GPE/CNT, and the macro-state, such as particle refinement, homogenization, and layered structure.

Design of mechanical-robust phosphorescence materials through covalent click reaction

It remains a great challenge to engineer materials with strong and stable interactions for the simultaneously mechanical-robust and room temperature phosphorescence-efficient materials. In this work, we demonstrate a covalent cross-linking strategy to engineer mechanical-robust room temperature phosphorescence materials through the B–O click reaction between chromophores, polyvinyl alcohol matrix and inorganic layered double hydroxide nanosheets. Through the covalent cross-linkage between the organic polyvinyl alcohol and inorganic layered double hydroxide, a polymeric composite with ultralong lifetime up to 1.45 s is acquired based on the inhibited non-radiative transition of chromophores. Simultaneously, decent mechanical strength of 97.9 MPa can be realized for the composite materials due to the dissipated loading stress through the covalent-bond-accommodated interfacial interaction. These cross-linked composites also exhibit flexibility, processability, scalability and phosphorescence responses towards the mechanical deformation. It is anticipated that the proposed covalent click reaction could provide a platform for the design and modulation of composites with multi-functionality and long-term durability.