Improved Bending Strength and Thermal Conductivity of Diamond/Al Composites with Ti Coating Fabricated by Liquid-Solid Separation Method

In response to the rapid development of high-performance electronic devices, diamond/Al composites with high thermal conductivity (TC) have been considered as the latest generation of thermal management materials. This study involved the fabrication of diamond/Al composites reinforced with Ti-coated diamond particles using a liquid-solid separation (LSS) method. The interfacial characteristics of composites both without and with Ti coatings were evaluated using SEM, XRD, and EMPA. The results show that the LSS technology can fabricate diamond/Al composites without Al4C3, hence guaranteeing excellent mechanical and thermophysical properties. The higher TC of the diamond/Al composite with a Ti coating was attributed to the favorable metallurgical bonding interface compounds. Due to the non-wettability between diamond and Al, the TC of uncoated diamond particle-reinforced composites was only 149 W/m·K. The TC of Ti-coated composites increased by 85.9% to 277 W/m·K. A simultaneous comparison and analysis were performed on the features of composites reinforced by Ti and Cr coatings. The results suggest that the application of the Ti coating increases the bending strength of the composite, while the Cr coating enhances the TC of the composite. We calculate the theoretical TC of the diamond/Al composite by using the differential effective medium (DEM) and Maxwell prediction model and analyze the effect of Ti coating on the TC of the composite.

Shear Bond Strength to Enamel, Mechanical Properties and Cellular Studies of Fiber-Reinforced Composites Modified by Depositing SiO2 Nanofilms on Quartz Fibers via Atomic Layer Deposition

Introduction

Poor interfacial bonding between the fibers and resin matrix in fiber-reinforced composites (FRCs) is a significant drawback of the composites. To enhance the mechanical properties of FRC, fibers were modified by depositing SiO2 nanofilms via the atomic layer deposition (ALD) technique. This study aims to evaluate the effect of ALD treatment of the fibers on the mechanical properties of the FRCs.

Methods

The quartz fibers were modified by depositing different cycles (50, 100, 200, and 400) of SiO2 nanofilms via the ALD technique and FRCs were proposed from the modified fibers. The morphologies, surface characterizations of nanofilms, mechanical properties, and cytocompatibility of FRCs were systematically investigated. Moreover, the shear bond strength (SBS) of FRCs to human enamel was also evaluated.

Results

The SEM and SE results showed that the ALD-deposited SiO2 nanofilms have good conformality and homogeneity. According to the results of FTIR and TGA, SiO2 nanofilms and quartz fiber surfaces had good chemical combinations. Three-point bending tests with FRCs showed that the deposited SiO2 nanofilms effectively improved FRCs' strength and Group D underwent 100 deposition cycles and had the highest flexural strength before and after aging. Furthermore, the strength of the FRCs demonstrated a crescendo-decrescendo tendency with SiO2 nanofilm thickness increasing. The SBS results also showed that Group D had outstanding performance. Moreover, the results of cytotoxicity experiments such as cck8, LDH and Elisa, etc., showed that the FRCs have good cytocompatibility.

Conclusion

Changing the number of ALD reaction cycles affects the mechanical properties of FRCs, which may be related to the stress relaxation and fracture between SiO2 nanofilm layers and the built-up internal stresses in the nanofilms. Eventually, the SiO2 nanofilms could enhance the FRCs' mechanical properties and performance to enamel by improving the interfacial bonding strength, and have good cytocompatibility.

Encapsulating Bi Nanoparticles in Reduced Graphene Oxide with Strong Interfacial Bonding toward Advanced Potassium Storage

Bismuth (Bi) is regarded as a promising anode material for potassium ion batteries (PIBs) due to its high theoretical capacity, but the huge volume expansion during potassiation and intrinsic low conductivity cause poor cycle stability and rate capability. Herein, a unique Bi nanoparticles/reduced graphene oxide (rGO) composite is fabricated by anchoring the Bi nanoparticles over the rGO substrate through a ball-milling and thermal reduction process. As depicted by the in-depth XPS analysis, strong interfacial Bi-C bonding can be formed between Bi and rGO, which is beneficial for alleviating the huge volume expansion of Bi during potassiation, restraining the aggregation of Bi nanoparticles and promoting the interfacial charge transfer. Theoretical calculation reveals the positive effect of rGO to enhance the potassium adsorption capability and interfacial electron transfer as well as reduce the diffusion energy barrier in the Bi/rGO composite. Thereby, the Bi/rGO composite exhibits excellent potassium storage performances in terms of high capacity (384.8 mAh g-1 at 50 mA g-1 ), excellent cycling stability (197.7 mAh g-1 after 1000 cycles at 500 mA g-1 with no capacity decay) and superior rate capability (55.6 mAh g-1 at 2 A g-1 ), demonstrating its great potential as an anode material for PIBs.

Investigating the Potential of Ghee Precursor-Derived Carbon Nano Onions for Enhancing Interfacial Bonding in Thermoplastic Composites

In this study, we employed a straightforward flame synthesis process to produce carbon soot containing carbon nano onions (CNOs) using easily accessible ghee oil as a precursor. The ghee oil, with a molecular composition rich in more than 50 carbon atoms, served as an effective source for generating CNOs. The synthesized CNO particles underwent comprehensive characterization through high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses, providing a detailed account of their physicochemical properties. In addition, we explored the direct deposition of CNOs on carbon fiber (CF) surfaces for 5 and 10 min via a soot deposition process. The resulting freeze-fracture images obtained from scanning electron microscope (SEM) offered insights into the morphology of the CNO-deposited CF. Our study aims to shed light on the potential applications of CNOs, focusing on their characterization and the possible benefits they may offer in diverse fields, including but not limited to enhancing interfacial bonding in thermoplastic composites.

Interfacial Properties of Three-Dimensional-Printed Permanent Formwork with Cast-in-Place Concrete

The rapid construction of prefabricated components of reinforced-concrete structures using three-dimensional (3D) printing of concrete as a permanent formwork is a promising way to combine 3D printing organically with traditional construction technology. The bonding property of the contact interface between the 3D-printed permanent formwork and internal postcast concrete is crucial for maintaining the overall mechanical performance of the 3D-printed structure. In this study, the roughness of contour formworks was quantified by using 3D scanning. A large-scale formwork was fabricated by using a robotic 3D printer, and four types of cast-in-place concrete were poured into the formwork to form solid components. The interfacial bonding properties between the formwork and cast material were evaluated by splitting tensile tests and antisymmetric four-point bending shear tests. The interfacial microstructure was analyzed by using computed tomography and scanning electron microscopy. The bond performance can mainly be attributed to the mechanical interlock at the interface between the contour formwork and cast aggregated concrete. The self-compacting concrete with the expansion agent contributes the most to the interface bonding.

Strong Connection of Single-Wall Carbon Nanotube Fibers with a Copper Substrate Using an Intermediate Nickel Layer

Lightweight carbon nanotube fibers (CNTFs) with high electrical conductivity and high tensile strength are considered to be an ideal wiring medium for a wide range of applications. However, connecting CNTFs with metals by soldering is extremely difficult due to the nonreactive nature and poor wettability of CNTs. Here we report a strong connection between single-wall CNTFs (SWCNTFs) and a Cu matrix by introducing an intermediate Ni layer, which enables the formation of mechanically strong and electrically conductive joints between SWCNTFs and a eutectic Sn-37Pb alloy. The electrical resistance change rate (ΔR/R0) of Ni-SWCNTF/solder-Cu interconnects only decreases ∼29.8% after 450 thermal shock cycles between temperatures of -196 and 150 °C, which is 8.2 times lower than that without the Ni layer. First-principles calculations indicate that the introduction of the Ni layer significantly improves the heterogeneous interfacial bond strength of the Ni-SWCNTF/solder-Cu connections.

Interfacial Bonding and Fracture Behaviors of AZ63 Magnesium Alloy Sheet Processed by Accumulative Roll Bonding

In order to understand the strengthening and the failure mechanism of accumulative roll bonding (ARB)-processed AZ63 Mg alloy, the interfacial bonding and fracture behavior of an ARB-processed AZ63 sheet were studied through electron microscopic analysis. The correlation between the mechanical properties, the microstructure, and the ARB processing parameters of an AZ63 sheet were presented. The experimental results have demonstrated that the average grain size of AZ63 Mg alloy processed by ARB was remarkably refined from 12.8 μm to 5.7 μm when the ARB processing temperature was set to 623 K, indicating the occurrence and development of dynamic recrystallization (DRX) nucleation. With the increase in ARB passes, the microstructure obviously became uniform. However, after five passes of the ARB process at 623 K, grains with different crystallographic orientations at the interface can be rearranged to generate the coherent eutectic plane, which inhibits the further refinement of grain size. During the ARB process of the AZ63 Mg alloy, the grain refinement was controlled by twin-induced recrystallization and dynamic recrystallization. Microcracks at the bonded interface of the ARB₁ sample were eliminated during the following 3~5 rolling passes at 623 K. After three passes of the ARB process at 623 K, the strength and elongation of the AZ63 Mg alloy increased from 232 MPa and 18.5% to 282 MPa and 26.3%, respectively. The tensile fracture morphology of the sample processed by three passes of ARB exhibited numerous dimples, and the slip lines caused by the cooperative deformation of refined grains can produce a network-like dimple structure, indicating that excellent ductile fracture characteristics could be obtained.

Quantifying Interfacial Bonding Using Thermal Boundary Conductance at Cubic Boron Nitride/Copper Interfaces with a Large Mismatch of Phonon Density of States

Interfacial bonding that directly influences the functional and mechanical properties of metal/nonmetal composites is commonly estimated by destructive pull-off measurements such as scratch tests, etc. However, these destructive methods may not be applicable under certain extreme environments; it is urgently necessary to develop a nondestructive quantification technique to determine the composite's performance. In this work, the time-domain thermoreflectance (TDTR) technique is applied to study the inter-relationship between interfacial bonding and interface characteristics through thermal boundary conductance (G) measurements. We think that interfacial phonon transmission capability plays a decisive role in influencing interfacial heat transport, especially for scenarios with a large mismatch of phonon density of states (PDOS). Moreover, we demonstrated this method at (100) and (111) cubic boron nitride/copper (c-BN/Cu) interfaces by both experimental and simulation efforts. The results show that the TDTR-measured G of the (100) c-BN/Cu interface (30 MW/m²·K) is about 20% higher than that of the (111) c-BN/Cu (25 MW/m²·K), which is ascribed to that higher interfacial bonding of the (100) c-BN/Cu endows it with better interfacial phonon transmission capability. In addition, detailed comparison of 10+ other metal/nonmetal interfaces exhibits similar positive relationship for interfaces with a large PDOS mismatch but negative relationship for interfaces with a small PDOS mismatch. The latter one is attributed to that extra inelastic phonon scattering and electron transport channels abnormally promoting interfacial heat transport. This work may provide some insights into quantitatively establishing inter-relationship between interfacial bonding and interface characteristics.

Study on Tungsten Metallization and Interfacial Bonding of Silicon Nitride High-Temperature Co-Fired Ceramic Substrates

For the first time, Si₃N₄ HTCC has been prepared using W as the metal phase by high-temperature co-firing (1830 °C/600 KPa/2 h) as a potential substrate candidate in electronic applications. It was discovered that the addition of Si₃N₄ to the W paste has a significant impact on thermal expansion coefficient matching and dissolution wetting. As the Si₃N₄ content increased from 0 to 27.23 vol%, the adhesion strength of W increased continuously from 2.83 kgf/mm² to 7.04 kgf/mm². The interfacial bonding of the Si₃N₄ ceramic and the conduction layer was discussed. SEM analysis confirmed that the interface between Si₃N₄ and W exhibited an interlocking structure. TEM, HRTEM and XRD indicated the formation of W₂C and W₅Si₃ due to the interface reactions of W with residual carbon and Si₃N₄, respectively, which contributed to the reactive wetting and good adhesion strength between the interface. Suitable amounts of Si₃N₄ powder and great interfacial bonding were the main reasons for the tough interfacial matching between the Si₃N₄ ceramic and the conduction layer.

Transition Metal β-diketonate Adhesion Promoters in Epoxy-Anhydride Resin

Epoxy to copper adhesion has occupied the center stage of electronic packaging to support the reliability of numerous novel structures. Compared to substrate pre-treatment, processing and cost considerations are greatly in favor of adhesion promoters in epoxy formulations to achieve exceptional adhesion and moisture resistance. In this paper, we present series of coordination compounds: first row transition metal β-diketonates to perform such function when added in epoxy/anhydride resins. The over 30% (before moisture aging) and 50% (after moisture aging) enhancement in lap shear strength were found using the champion metal chelates, notably Co(II) and Ni(II) hexafluoroacetylacetonate (6Facac₂ ), where interesting metal and ligand dependence on the adhesion properties were also observed. From extensive surface bond composition analyses on the adhesively failed samples using X-ray Photoelectron Spectroscopy (XPS), we found that the increased population of oxygen containing functional groups, especially esters, are fundamental for the adhesion improvement. Assisted by XPS depth profile on the fractured epoxy side and in-situ Fourier-transform Infrared Spectroscopy (FTIR) tracking epoxy-anhydride curing, our previously discovered latent cure performances of the metal chelate additives through interacting with phosphine catalysts were regarded pivotal for pacing anhydride and acid intermediate consumption, which is necessary for the very localized interfacial esterification reactions to occur and provide abundant covalent bonding between the adhesive and the adherend. Further examinations on the XPS binding energy of polar functional groups, as well as contact angle and dielectric spectroscopy of the doped epoxy also revealed metal-polymer (and interfacial bonding) coordination that contributed to the adhesion and moisture resistance properties. These findings demonstrate the use of transition metal complexes as promising adhesion promoters in epoxy resins, and the mechanisms discussed here should be helpful in stimulating future design of functional additives pursuing both cure kinetics control and polar group coordination ideas for more robust epoxy-Cu joints. This article is protected by copyright. All rights reserved.

Flexible-to-Stretchable Mechanical and Electrical Interconnects

Stretchable electronic devices that maintain electrical function when subjected to stress or strain are useful for enabling new applications for electronics, such as wearable devices, human-machine interfaces, and components for soft robotics. Powering and communicating with these devices is a challenge. NFC (near-field communication) coils solve this challenge but only work efficiently when they are in close proximity to the device. Alternatively, electrical signals and power can arrive via physical connections between the stretchable device and an external source, such as a battery. The ability to create a robust physical and electrical connection between mechanically disparate components may enable new types of hybrid devices in which at least a portion is stretchable or deformable, such as hinges. This paper presents a simple method to make mechanical and electrical connections between elastomeric conductors and flexible (or rigid) conductors. The adhesion at the interface between these disparate materials arises from surface chemistry that forms strong covalent bonds. The utilization of liquid metals as the conductor provides stretchable interconnects between stretchable and non-stretchable electrical traces. The liquid metal can be printed or injected into vias to create interconnects. We characterized the mechanical and electrical properties of these hybrid devices to demonstrate the concept and identify geometric design criteria to maximize mechanical strength. The work here provides a simple and general strategy for creating mechanical and electrical connections that may find use in a variety of stretchable and soft electronic devices.

Effects of Lysine on the Interfacial Bonding of Epoxy Resin Cross-Linked Soy-Based Wood Adhesive

Soy protein isolate (SPI) is an attractive natural material for preparing wood adhesives that has found broad application. However, poor mechanical properties and unfavorable water resistance of wood composites with SPI adhesive bonds limit its more extensive utilization. The combination of lysine (Lys) with a small molecular structure as a curing agent for modified soy-based wood adhesive allows Lys to penetrate wood pores easily and can result in better mechanical strength of soy protein-based composites, leading to the formation of strong chemical bonds between the amino acid and wood interface. Scanning electron microscopy (SEM) results showed that the degree of penetration of the S/G/L-9% adhesive into the wood was significantly increased, the voids, such as ducts of wood at the bonding interface, were filled, and the interfacial bonding ability of the plywood was enhanced. Compared with the pure SPI adhesive, the corresponding wood breakage rate was boosted to 84%. The wet shear strength of the modified SPI adhesive was 0.64 MPa. When Lys and glycerol epoxy resin (GER) were added, the wet shear strength of plywood prepared by the S/G/L-9% adhesive reached 1.22 MPa, which increased by 29.8% compared with only GER (0.94 MPa). Furthermore, the resultant SPI adhesive displayed excellent thermostability. Water resistance of S/G/L-9% adhesive was further enhanced with respect to pure SPI and S/GER adhesives through curing with 9% Lys. In addition, this work provides a new and feasible strategy for the development and application of manufacturing low-cost, and renewable biobased adhesives with excellent mechanical properties, a promising alternative to traditional formaldehyde-free adhesives in the wood industry.

Interfacial Engineering Methods in Thermoplastic Composites: An Overview

The paper critically analyzed different interfacial enhancing methods used in thermoplastic composites. Although the absence of cross-linked polymer chains and chemical bonds on solidification enables the thermoplastics to be remelted, it creates weak interfacial adhesion between fibre reinforcements and the thermoplastic matrix. The weak fibre-matrix interface bonding reduces the efficiency with which the applied load can be transferred between these composite constituents, causing the composite to fail prematurely. Their need for high-temperature processing, poor compatibility with other polymer matrices, and relatively high viscosity render thermoplastics challenging when used to manufacture composite laminates. Therefore, various methods, including nanoparticles, changing the polarity of the fibre surface by plasma etching, chemical treatment with ozone, or an oxidative attack at the fibre surface, have been applied to improve the fibre/matrix bonding in thermoplastic composites. The fabrication steps followed in these techniques, their progress in research, and the associated toughening mechanisms are comprehensively discussed in this paper. The effect of different fibre-matrix interfacial enhancement methods on the mechanical properties of thermoplastic composites is also deliberated.

Mechanical Properties of Fly Ash-Based Geopolymer Concrete Incorporation Nylon66 Fiber

This study was carried out to investigate the effect of the diamond-shaped Interlocking Chain Plastic Bead (ICPB) on fiber-reinforced fly ash-based geopolymer concrete. In this study, geopolymer concrete was produced using fly ash, NaOH, silicate, aggregate, and nylon66 fibers. Characterization of fly ash-based geopolymers (FGP) and fly ash-based geopolymer concrete (FRGPC) included chemical composition via XRF, functional group analysis via FTIR, compressive strength determination, flexural strength, density, slump test, and water absorption. The percentage of fiber volume added to FRGPC and FGP varied from 0% to 0.5%, and 1.5% to 2.0%. From the results obtained, it was found that ICBP fiber led to a negative result for FGP at 28 days but showed a better performance in FRGPC reinforced fiber at 28 and 90 days compared to plain geopolymer concrete. Meanwhile, NFRPGC showed that the optimum result was obtained with 0.5% of fiber addition due to the compressive strength performance at 28 days and 90 days, which were 67.7 MPa and 970.13 MPa, respectively. Similar results were observed for flexural strength, where 0.5% fiber addition resulted in the highest strength at 28 and 90 days (4.43 MPa and 4.99 MPa, respectively), and the strength performance began to decline after 0.5% fiber addition. According to the results of the slump test, an increase in fiber addition decreases the workability of geopolymer concrete. Density and water absorption, however, increase proportionally with the amount of fiber added. Therefore, diamond-shaped ICPB fiber in geopolymer concrete exhibits superior compressive and flexural strength.

Reducing interfacial thermal resistance by interlayer

Heat dissipation is crucial important for the performance and lifetime for highly integrated electronics, Li-ion battery-based devices and so on, which lies in the decrease of interfacial thermal resistance (ITR). To achieve this goal, introducing interlayer is the most widely used strategy in industry, which has attracted tremendous attention from researchers. In this review, we focus on bonding effect and bridging effect to illustrate how introduced interlayer decreases ITR. The behind mechanisms and theoretical understanding of these two effects are clearly illustrated. Simulative and experimental studies toward utilizing these two effects to decrease ITR of real materials and practical systems are reviewed. Specifically, the mechanisms and design rules for the newly emerged graded interlayers are discussed. The optimization of interlayers by machine learning algorithms are reviewed. Based on present researches, challenges and possible future directions about this topic are discussed.

A Constrained Assembly Strategy for High-Strength Natural Nanoclay Film

Developing high-performance materials from existing natural materials is highly desired because of their environmental friendliness and low cost; two-dimensional nanoclay exfoliated from layered silicate minerals is a good building block to construct multilayered macroscopic assemblies for achieving high mechanical and functional properties. Nevertheless, the efforts have been frustrated by insufficient inter-nanosheet stress transfer and nanosheet misalignment caused by capillary force during solution-based spontaneous assembly, degrading the mechanical strength of clay-based materials. Herein, a constrained assembly strategy that is implemented by in-plane stretching a robust water-containing nanoclay network with hydrogen and ionic bonding is developed to adjust the 2D topography of nanosheets within multilayered nanoclay film. In-plane stretching overcomes capillary force during water removal and thus restrains nanosheet conformation transition from nearly flat to wrinkled, leading to a highly aligned multilayered nanostructure with synergistic hydrogen and ionic bonding. It is proved that inter-nanosheet hydrogen and ionic bonding and nanosheet conformation extension generate profound mechanical reinforcement. The tensile strength and modulus of natural nanoclay film reach up to 429.0 MPa and 43.8 GPa and surpass the counterparts fabricated by normal spontaneous assembly. Additionally, improved heat insulation function and good nonflammability are shown for the natural nanoclay film and extend its potential for realistic uses.

Modification and Characterization of Interfacial Bonding for Thermal Management of Ruthenium Interconnects in Next-Generation Very-Large-Scale Integration Circuits

Ruthenium may replace copper interconnects in next-generation very-large-scale integration (VLSI) circuits. However, interfacial bonding between Ru interconnect wires and surrounding dielectrics must be optimized to reduce thermal boundary resistance (TBR) for thermal management. In this study, various adhesion layers are employed to modify bonding at the Ru/SiO₂ interface. The TBRs of film stacks are measured using the frequency-domain thermoreflectance technique. TiN and TaN with high nitrogen contents significantly reduce the TBR of the Ru/SiO₂ interface compared to common Ti and Ta adhesion layers. The adhesion layer thickness, on the other hand, has only minor effect on TBR when the thickness is within 2-10 nm. Hard X-ray photoelectron spectroscopy of deeply buried layers and interfaces quantitatively reveals that the decrease in TBR is attributed to the enhanced bonding of interfaces adjacent to the TaN adhesion layer, probably due to the electron transfer between the atoms at two sides of the interface. Simulations by a three-dimensional electrothermal finite element method demonstrate that decreasing the TBR leads to a significantly smaller temperature increase in the Ru interconnects. Our findings highlight the importance of TBR in the thermal management of VLSI circuits and pave the way for Ru interconnects to replace the current Cu-based ones.

New Synthesis Routes toward Improvement of Natural Filler/Synthetic Polymer Interfacial Crosslinking

Among the critical issues dictating bio-composite performance is the interfacial bonding between the natural fibers and polymer matrix. In this regard, this article presents new synthesis routes comprising the treatment and functionalization of both date palm powder (DPP) filler and a polypropylene (PP) matrix to enhance filler–polymer adhesion in the newly developed bio-composites. Specifically, four bio-composite forms are considered: untreated DPP filled PP (DPP-UT/PP), treated DPP filled PP (DPP-T/PP), treated DPP filled functionalized PP using 2-isocyanatoethyl methacrylate (DPP-T/PP-g-IEM), and treated and functionalized DPP using 4-toluenesulfonyl chloride filled functionalized PP using 2-acrylamide ((DPP-T)-g-TsCl/PP-g-AcAm). The functional groups created on the surface of synthesized PP-g-IEM react with activated hydroxyl groups attached to the filler, resulting in chemical crosslinking between both components. Similarly, the reaction of TsCl with NH₂ chemical groups residing on the mating surfaces of the filler and polymer generates an amide bond in the interface region. Fourier transform infrared spectroscopy (FTIR) is used to confirm the successful coupling between the filler and polypropylene matrix after applying the treatment and functionalization schemes. Owing to the introduced crosslinking, the DPP-T/PP-g-IEM bio-composite exhibits the best mechanical properties as compared to the neat polymer, unfunctionalized polymer-based bio-composite, and (DPP-T)-g-TsCl/PP-g-AcAm counterpart. The applied compatibilizers assist in reducing the water uptake of the manufactured bio-composites, increasing their durability.

Temperature Dependence of Interfacial Bonding and Configuration Transition in Graphene/Hexagonal Boron Nitride Containing Grain Boundaries and Functional Groups

The quasi-three-dimensional effect induced by functional groups (FGo) and the in-plane stress and structural deformation induced by grain boundaries (GBs) may produce more novel physical effects. These physical effects are particularly significant in high-temperature environments and are different from the behavior in bulk materials, so its physical mechanism is worth exploring. Considering the external field (strain and temperature field), the internal field (FGo and GBs) and the effect of distance between FGs and GBs on the bonding energy, configuration transition, and stress distribution of graphene/h-BN with FGo and GBs (GrO-BN-GBs) in the interface region were studied by molecular dynamics (MD). The results show that the regions linked by hydroxyl + epoxy groups gradually change from honeycomb to diamond-like structures as a result of a hybridization transition from sp² to sp³. The built-in distortion stress field generated by the coupling effect of temperature and tension loading induces the local geometric buckling of two-dimensional materials, according the von Mises stresses and deflection theory. In addition, the internal (FGo and GBs) and external field (strain and temperature field) have a negative chain reaction on the mechanical properties of GrO-BN-GBs, and the negative chain reaction increases gradually with the increase in the distance between FGo and GBs. These physical effects are particularly obvious in high-temperature environments, and the behavior of physical effects in two-dimensional materials is different from that in bulk materials, so its physical mechanism is worth exploring.

Rivet-Inspired Modification of Carbon Nanotubes by In Situ-Reduced Ag Nanoparticles To Enhance the Strength and Ductility of Zn Implants

Zinc shows promise for bone repair applications, while its strength and ductility require to be improved. Carbon nanotubes (CNTs) are exceptional reinforcements due to their superior strength, ultrahigh Young's modulus, and large aspect ratio. However, their strong agglomeration and weak interfacial bonding with the matrix are key bottleneck problems restricting the reinforcing effect. In this study, Ag nanoparticles were in situ reduced on CNTs and then the CNT@Ag powders were used to prepare Zn-CNT@Ag implants by laser powder bed fusion. Results showed that Ag reacted with Zn to form a "knot"-like AgZn₃ phase. It had the same lattice structure (HCP) with Zn, which indicated a good lattice matching with the matrix, thus improving the dispersion of CNTs. More significantly, the knot played a "rivet" role and enhanced the load transfer capacity, which advantaged the CNT strengthening effects by assisting in transferring the load. Moreover, it enhanced the heterogeneous nucleation effects during solidification, which weakened the texture strength of the matrix and thus increased the ductility by improving the sliding capacity. The compressive yield strength, ultimate tensile strength, and elongation of the Zn-CNT@Ag implant were increased by 22, 26, and 17% in comparison to Zn-CNTs. Moreover, the Zn-CNT@Ag implant exhibited favorable antibacterial activity with a bacterial inhibition rate of 87.79%. Additionally, it also exhibited a suitable degradation rate and acceptable biocompatibility.

Effects of Coupling Agent and Thermoplastic on the Interfacial Bond Strength and the Mechanical Properties of Oriented Wood Strand-Thermoplastic Composites

Wood-plastic composites (WPC) with good mechanical and physical properties are desirable products for manufacturers and customers, and interfacial bond strength is one of the most critical factors affecting WPC performance. To verify that a higher interfacial bond strength between wood and thermoplastics improves WPC performance, wood veneer-thermoplastic composites (VPC) and oriented strand-thermoplastic composites (OSPC) were fabricated using hot pressing. The effects of the coupling agent (KH550 or MDI) and the thermoplastic (LDPE, HDPE, PP, or PVC) on the interfacial bond strength of VPC, and the mechanical and physical properties of OSPC, were investigated. The results showed that coupling agents KH550 and MDI improved the interfacial bond strength between wood and thermoplastics under dry conditions. MDI was better than KH550 at improving the interfacial bond strength and the mechanical properties of OSPC. Better interfacial bonding between plastic and wood improved the OSPC performance. The OSPC fabricated using PVC film as the thermoplastic and MDI as the coupling agent displayed the highest mechanical properties, with a modulus of rupture of 91.9 MPa, a modulus of elasticity of 10.9 GPa, and a thickness swelling of 2.4%. PVC and MDI are recommended to fabricate WPCs with desirable performance for general applications.

Mechanical Robustness of Metal Nanocomposites Rendered by Graphene Functionalization

Nanocarbon materials, such as graphene, carbon nanotubes, and their derivatives, are considered highly effective reinforcing agents in metals. Copious experimental and computational observations suggest that the nature of the interfaces may significantly affect the mechanical behavior of nanocarbon-metal composites, while the exact correlation between the interfacial structure and the deformation and failure mechanisms of the composite remains elusive. Using a nanolaminated graphene-aluminum (Al) composite as the model material, we designed and created composites with distinct interfacial structures and bonding states via graphene functionalization. The mechanical behavior of the composites was strongly affected by the structure of the functionalized graphene (FG)/Al interface, and the optimum strength-ductility synergy came from the composite with the intermediate extent of functionalization. Complementing experimental results with molecular dynamics and phase-field simulation efforts, we interpreted these results by the combined effects of the intrinsic strength of FG nanosheets and the FG/Al interfacial bonding state.

Preparation and Performance of Cement Mortar Reinforced by Modified Bamboo Fibers

This study aims to prepare bamboo-fiber-reinforced cement composites and provide a solution to the issue of poor interfacial adhesion between bamboo fibers and cement matrix. The original bamboo fibers were modified by three moderately low-cost and easy-to-handle treatments including glycerol, aluminate ester, and silane treatments. The performance of the modified bamboo-fiber-reinforced cement composites was evaluated by a series of mechanical and durability tests, including flexural and compressive strength, water absorption, chloride ion penetration, drying shrinkage, freeze-thaw resistance, and carbonization. In addition, the microstructures of composites were characterized using a scanning electron microscope (SEM). The results showed that the composites reinforced with glycerol-modified bamboo fibers had 14% increased flexural strength and comparable compressive strength. From durability perspectives, all treatments showed similar performance in drying shrinkage, whereas aluminate ester treatment was the most effective in terms of impermeability, chloride resistance, freeze-thaw resistance, and carbonization. The results could provide insights to efficient and effective natural fiber treatment to enable better performance of natural-fiber-reinforced cement-based materials.

Effect of Molecular Weight of Self-Emulsifying Amphiphilic Epoxy Sizing Emulsions on the Carbon Fibres and Interfacial Properties of Their Composites

The molecular weight of self-emulsifying amphiphilic epoxy sizing emulsions has a big effect on the carbon fibres and interfacial properties of their composites. Novel amphiphilic epoxy sizing emulsions with four different molecular weights (7500, 11,000, 15,000 and 17,000) were successfully prepared by a self-emulsifying method and applied to improve interfacial bonding between carbon fibres (CFs) and an epoxy resin (EP). The effect of molecular weight on the quality of emulsions, the sized CFs and the interfacial properties of the CF/EP composite system were studied. The results reveal that these novel sizing emulsions exhibited strong emulsifying ability and high processability. The most favourable wettability and adequate CF surface free energy were obtained by the emulsion with a molecular weight of 7500. Compared with unsized CFs, the monofilament fibre tensile performance was remarkably improved when increasing the shape parameter from 5.08 to 7.20. The interfacial sheer strength (IFSS) of the CF/EP composite was greatly increased by 96% with the emulsion of 7500. The enhanced interfacial adhesion benefits were attributed mainly from the enhanced charge interaction between CFs and the sizing layer as well as the compatibility and the mechanical interlock between the sizing layer and the epoxy matrix.

Rubber Recycling: Mending the Interface between Ground Rubber Particles and Virgin Rubber

The interface between ground rubber particles (GRPs) and virgin rubber is the focus of this investigation that aims to mitigate the detriments caused by recycled GRPs blended in virgin rubber. By studying laminates of cured and uncured rubber strips as models for the interface, modulus contrast across the interface has been identified as another cause for the poor mechanical properties of vulcanizates containing GRPs, in additional to poor interfacial bonding. A surface-devulcanization method was established to improve molecular contact between the GRPs and virgin rubber and consequently raised the adhesion energy to the level of cohesion energy. The interfacial modulus contrast that causes stress concentration at the interface was likely a result of diffusion of curatives from the virgin rubber to the GRPs. The modulus contrast was erased by diffusion of piperidine from the GRPs into the virgin rubber. Piperidine acted as a vulcanization accelerator, making sulfur cross-linking within the virgin rubber outcompete sulfur diffusion into the GRPs. Mending the interface improved the tensile strength of vulcanizates containing GRPs to a level close to that of the virgin rubber vulcanizate but did not improve the extensibility.

Amyloid-Like Protein Aggregates: A New Class of Bioinspired Materials Merging an Interfacial Anchor with Antifouling

Surfaces that resist nonspecific protein adsorption in a complex biological milieu are required for a variety of applications. However, few strategies can achieve a robust antifouling coating on a surface in an easy and reliable way, regardless of material type, morphology, and shape. Herein, the preparation of an antifouling coating by one-step aqueous supramolecular assembly of bovine serum albumin (BSA) is reported. Based on fast amyloid-like protein aggregation through the rapid reduction of the intramolecular disulfide bonds of BSA by tris(2-carboxyethyl)phosphine, a dense proteinaceous nanofilm with controllable thickness (≈130 nm) can be covered on virtually arbitrary material surfaces in tens of minutes by a simple dipping or spraying. The nanofilm shows strong stability and adhesion with the underlying substrate, exhibiting excellent resistance to the nonspecific adsorption of a broad-spectrum of contaminants including proteins, serum, cell lysate, cells, and microbes, etc. In vitro and in vivo experiments show that the nanofilm can prevent the adhesion of microorganisms and the formation of biofilm. Compared with native BSA, the proteinaceous nanofilm coating exposes a variety of functional groups on the surface, which have more-stable adhesion with the surface and can maintain the antifouling in harsh conditions including under ultrasound, surfactants, organic solvents, and enzymatic digestion.

TiO2-Induced In Situ Reaction in Graphene Oxide-Reinforced AZ61 Biocomposites to Enhance the Interfacial Bonding

Graphene oxide (GO) can improve the degradation resistance of biomedical Mg alloy because of its excellent impermeability and outstanding chemical inertness. However, the weak interfacial bonding between GO and Mg matrix leads to easily detaching during degradation. In this study, in situ reaction induced by TiO₂ took place in the AZ61-GO biocomposite to enhance the interfacial bonding between GO and Mg matrix. For the specific process, TiO₂ was uniformly and tightly deposited onto the GO surface by hydrothermal reaction (TiO₂/GO) first and then used for fabricating AZ61-TiO₂/GO biocomposites by selective laser melting (SLM). Results showed that TiO₂ was in situ reduced by magnesiothermic reaction during SLM process, and the reduzate Ti, on the one hand, reacted with Al in the AZ61 matrix to form TiAl₂ and, on the other hand, reacted with GO to form TiC at the AZ61-GO interface. Owing to the enhanced interfacial bonding, the AZ61-TiO₂/GO biocomposite showed 12.5% decrease in degradation rate and 10.1% increase in compressive strength as compared with the AZ61-GO biocomposite. Moreover, the AZ61-TiO₂/GO biocomposite also showed good cytocompatibility because of the slowed degradation. These findings may provide guidance for the interfacial enhancement in GO/metal composites for biomedical applications.

The Interfacial Characteristics of Graphene/Al4C3 in Graphene/AlSi10Mg Composites Prepared by Selective Laser Melting: First Principles and Experimental Results

The Al₄C₃ phase was precipitated via a reaction of graphene (Gr) with Al during selective laser melting (SLM). The interfacial nature of the Gr (0001)/Al₄C₃ (0001) interface was determined using the first-principle calculation. The simulation results showed that the influence of the stacking site on the interfacial structure was limited and the Al-termination interface presented a more stable structure than the C-termination interface. The Al-termination-CH site interface had the largest work of adhesion (6.28 J/m²) and the smallest interfacial distance (2.02 Å) among the four interfacial structures. Mulliken bond population analysis showed that the bonding of the Al-termination interface was a mixture of covalent and ionic bonds and there was no chemical bonding in the C-termination interface.

Graphene/Half-Metallic Heusler Alloy: A Novel Heterostructure toward High-Performance Graphene Spintronic Devices

Graphene-based vertical spin valves (SVs) are expected to offer a large magnetoresistance effect without impairing the electrical conductivity, which can pave the way for the next generation of high-speed and low-power-consumption storage and memory technologies. However, the graphene-based vertical SV has failed to prove its competence due to the lack of a graphene/ferromagnet heterostructure, which can provide highly efficient spin transport. Herein, the synthesis and spin-dependent electronic properties of a novel heterostructure consisting of single-layer graphene (SLG) and a half-metallic Co₂ Fe(Ge_0.5 Ga_0.5 ) (CFGG) Heusler alloy ferromagnet are reported. The growth of high-quality SLG with complete coverage by ultrahigh-vacuum chemical vapor deposition on a magnetron-sputtered single-crystalline CFGG thin film is demonstrated. The quasi-free-standing nature of SLG and robust magnetism of CFGG at the SLG/CFGG interface are revealed through depth-resolved X-ray magnetic circular dichroism spectroscopy. Density functional theory (DFT) calculation results indicate that the inherent electronic properties of SLG and CFGG such as the linear Dirac band and half-metallic band structure are preserved in the vicinity of the interface. These exciting findings suggest that the SLG/CFGG heterostructure possesses distinctive advantages over other reported graphene/ferromagnet heterostructures, for realizing effective transport of highly spin-polarized electrons in graphene-based vertical SV and other advanced spintronic devices.

Phosphonic Acid Coupling Agent Modification of HAP Nanoparticles: Interfacial Effects in PLLA/HAP Bone Scaffold

In order to improve the interfacial bonding between hydroxyapatite (HAP) and poly-l-lactic acid (PLLA), 2-Carboxyethylphosphonic acid (CEPA), a phosphonic acid coupling agent, was introduced to modify HAP nanoparticles. After this. the PLLA scaffold containing CEPA-modified HAP (C-HAP) was fabricated by selective laser sintering (frittage). The specific mechanism of interfacial bonding was that the PO32- of CEPA formed an electrovalent bond with the Ca2+ of HAP on one hand, and on the other hand, the -COOH of CEPA formed an ester bond with the -OH of PLLA via an esterification reaction. The results showed that C-HAP was homogeneously dispersed in the PLLA matrix and that it exhibited interconnected morphology pulled out from the PLLA matrix due to the enhanced interfacial bonding. As a result, the tensile strength and modulus of the scaffold with 20% C-HAP increased by 1.40 and 2.79 times compared to that of the scaffold with HAP, respectively. In addition, the scaffold could attract Ca2+ in simulated body fluid (SBF) solution by the phosphonic acid group to induce apatite layer formation and also release Ca2+ and PO43- by degradation to facilitate cell attachment, growth and proliferation.

Surface Modification of Bamboo Fibers to Enhance the Interfacial Adhesion of Epoxy Resin-Based Composites Prepared by Resin Transfer Molding

Bamboo fibers (BFs)-reinforced epoxy resin (EP) composites are prepared by resin transfer molding (RTM). The influence of BFs surface modification (NaOH solution or coupling agents, i.e., KH550 and KH560) on interfacial properties of BFs/EP composites is systematically investigated. The synergistic effect of hydrolysis, peeling reaction of BFs, and the condensation reaction of hydrolyzed coupling agents are confirmed by FTIR. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveal that the interfacial compatibility of NaOH- and silane-modified BFs/EP composites was significantly improved. KH550-modified BFs/EP composite renders optimal tensile, flexural, and impact strength values of 68 MPa, 86 MPa, and 226 J/m. The impact resistance mechanism at the interface of BFs/EP composites was proposed. Moreover, the dynamic mechanical properties, creep behavior, and differential scanning calorimetry of BFs/EP composites have also been carried out to understand thermal stabilities. Overall, the surface-modified BFs-reinforced EP composites exhibited superior interfacial bonding.

Effect of Fiber Surface Modification on the Interfacial Adhesion and Thermo-Mechanical Performance of Unidirectional Epoxy-Based Composites Reinforced with Bamboo Fibers

In this work, bamboo fibers are chemically modified with NaOH solution of 1, 4, and 7 wt% concentrations at room temperature, respectively, and subsequently the untreated and treated fibers are prepared with epoxy resin for unidirectional composites by hot pressing molding technique. Tensile and micro-bond tests are conducted on the composite specimens to obtain mechanical properties, such as tensile strength and modulus, elongation at break, and interfacial strength. Besides, scanning electron microscopy (SEM) is employed to perform morphological observations for constituent damages. In addition, the influence of alkali concentration on the thermal performance of epoxy-based composites is examined by using differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. It is found that composite tensile strength reaches the maximum when the alkali concentration is 4%, increased by 45.24% compared with untreated composites. The composite elongation at break increases on increasing the concentration. Inversely, the composite modulus decreases as the concentration increases. Besides, the results demonstrate that the chemical treatment on the fiber surface could improve interface adhesion, as observed from its topography by SEM. Micro-bond test reveals that there is maximum interfacial shear strength when the alkali concentration is 4%, which increases by 100.30% in comparison with the untreated samples. In case of thermal properties, the DSC analysis indicates that the glass transition temperature is maximized at 4% alkali concentration, which is increased by 12.95%, compared to those from unmodified fibers. In addition, TG results show that the 4% concentration also facilitates thermal stability improvement, indicative of superior interfacial bonding.

Spatial Mapping of Thermal Boundary Conductance at Metal-Molybdenum Diselenide Interfaces

Improving the thermal transport across interfaces is a necessary consideration for micro- and nanoelectronic devices and necessitates accurate measurement of the thermal boundary conductance (TBC) and understanding of transport mechanisms. Two-dimensional transition-metal dichalcogenides (TMDs) have been studied extensively for their electrical properties, including the metal-TMD electrical contact resistance, but the thermal properties of these interfaces are significantly less explored irrespective of their high importance in their electronic devices. We isolate individual islands of MoSe₂ grown by chemical vapor deposition using photolithography and correlate the 2D variation of TBC with optical microscope images of the MoSe₂ islands. We measure the 2D spatial variation of the TBC at metal-MoSe₂-SiO₂ interfaces using a modified time-domain thermoreflectance (TDTR) technique, which requires much less time than full TDTR scans. The thermoreflectance signal at a single probe delay time is compared with a correlation curve, which enables us to estimate the change in the signal with respect to the TBC at the metal-MoSe₂-SiO₂ interface as opposed to recording the decay of the thermoreflectance signal over delay times of several nanoseconds. The results show a higher TBC across the Ti-MoSe₂-SiO₂ interface compared to Al-MoSe₂-SiO₂. An image-clustering method is developed to differentiate the TBC for different numbers of MoSe₂ layers, which reveals that the TBC in single-layer regions is higher than that in the bilayer. We perform traditional TDTR measurements over a range of delay times and verify that TBC is higher at the Ti-MoSe₂-SiO₂ interface compared to Al-MoSe₂-SiO₂, highlighting the importance of the choice of metal for heat dissipation at electrical contacts in TMD devices.

Enhancing Interfacial Bonding and Tensile Strength in CNT-Cu Composites by a Synergetic Method of Spraying Pyrolysis and Flake Powder Metallurgy

Carbon nanotube (CNT)-reinforced metal matrix composites (MMCs) face the problems of dispersion and interfacial wetting with regard to the matrix. A synergetic method of spray pyrolysis (SP) and flake powder metallurgy (FPM) is used in this paper to improve the dispersibility and interfacial bonding of CNTs in a Cu matrix. The results of the interface characterization show interface oxygen atoms (in the form of Cu₂O) and a high density of dislocation areas, which is beneficial for interfacial bonding. The tensile results show that the tensile strength of the SP-CNT-Cu composites is much higher than that of the CNT-Cu composites when the mass fraction of the CNTs does not reach the critical value. This can be explained by the nanoparticles which are found on the surface of the CNTs during the SP process. These nanoparticles not only increase the tensile strength of the SP-CNT-Cu composites but also improve the dispersion of the CNTs in the Cu matrix. Thereby, uniform dispersion of CNTs, interfacial bonding between CNTs and the Cu matrix, and the enhancement of tensile strength are achieved simultaneously by the synergetic method.

Effect of Compatibilizer on the Interface Bonding of Graphene Oxide/Polypropylene Composite Fibers

To improve the interfacial bonding and thermal stability of graphene oxide (GO)/polypropylene (PP) composite fibers, a composite fiber with PP as the matrix, GO as reinforcement and maleic anhydride-grafted PP (PP-g-MAH) as a compatibilizer was prepared by a simple and efficient melt-blending method. The GO content was 0.0–5.0 wt %. According to the Fourier Transform Infrared (FT-IR) spectroscopy results, the interfacial bonding in the PP/MAH/GO composite fibers was improved. The Dynamic Mechanical Analysis (DMA) results show that the addition of GO resulted in better interfacial adhesion and higher storage modulus (E′). The loss modulus (E″) of the PP/MAH/GO-x composite fibers increased with increasing amount of added GO, whereas the loss factor (tan δ) decreased. GO and PP-g-MAH were analyzed by Thermogravimetric Analysis (TGA). The thermal stability of the composite fibers was improved compared to PP. Differential Scanning Calorimetry (DSC) analysis showed that the addition of PP-g-MAH to the composite fiber improved the interfacial bonding of GO in the PP matrix. Thus, compatibility between the two components was obtained. Based on the Scanning Electron Microscopy (SEM) results, the PP fibers exhibited relative orientation due to the strong crystalline morphology. The rough section, PP/GO blend fiber exhibits a very clear phase separation morphology due to the incompatibility between the two and the compatibility of GO and PP in PP/MAH/GO-3 composite fiber is improved, resulting in the interface between the two has improved.

Water-Switchable Interfacial Bonding on Tooth Enamel Surface

Tooth enamel is a distinctive nanocomposite with a highly organized hierarchical structure made of nanometer- and micrometer-scale building blocks. This structure has an excellent mechanical function that can last for decades thanks to an effective but underexploited interfacial chemical bonding between the building blocks. In this study, the nanomechanical system test (NST), scanning electron microscope (SEM), X-ray diffraction (XRD, including powder XRD or PXRD, small angle XRD or SAXRD, and grazing incidence small angle XRD or GISAXRD), and atomic force microscope (AFM) have been employed to analyze the water-mediated bonding on the enamel surface. Via the cycling between hydration, dehydration, and rehydration treatments, a reversible change in the interfacial distance (i.e., d-space in the XRD pattern) between hydroxyapatite (HAP) nanocrystallites have been found switchable between the embrittling and toughening on the enamel surface. From the hydrated to the dehydrated conditions, an energy dissipation to deform a unit volume (1 μm³) of biocomposite on the enamel surface and subsurface has decreased by 20%. This finding can help quantify and predict biomineral-surface properties in all humidity and develop new methods to protect tooth enamel of "dry-mouth" patients.

In-Situ Preparation of Aramid-Multiwalled CNT Nano-Composites: Morphology, Thermal Mechanical and Electric Properties

In this work in-situ polymerization technique has been used to chemically link the functionalized multiwalled carbon nanotubes (CNTs) with aramid matrix chains. Phenylene diamine monomers were reacted in the first stage with the carboxylic acid functionalized CNTs and then amidized in-situ using terephthaloyl chloride generating chemically bonded CNTs with the matrix. Various proportions of the CNTs were used to prepare the hybrid materials. The functionalization procedure was studied by Fourier transform infrared (FTIR) spectroscopy and composite morphology investigated by scanning electron microscopy (SEM). Thermal mechanical properties of these hybrids, together with those where pristine CNTs with similar loadings were used, are compared using tensile and dynamic mechanical analysis (DMA). The tensile strength and temperature involving α-relaxations on CNT loading increased with CNT loading in both systems, but much higher values, i.e., 267 MPa and 353 °C, respectively, were obtained in the chemically bonded system, which are related to the nature of the interface developed as observed in SE micrographs. The water absorption capacity of the films was significantly reduced from 6.2 to 1.45% in the presence pristine CNTs. The inclusion of pristine CNTs increased the electric conductivity of the aramid films with a minimum threshold value at the loading of 3.5 wt % of CNTs. Such mechanically strong and thermally stable aramid and easily processable composites can be suitable for various applications including high performance films, electromagnetic shielding and radar absorption.

Ni Nanobuffer Layer Provides Light-Weight CNT/Cu Fibers with Superior Robustness, Conductivity, and Ampacity

Carbon nanotube (CNT) fiber has not shown its advantage as next-generation light-weight conductor due to the large contact resistance between CNTs, as reflected by its low conductivity and ampacity. Coating CNT fiber with a metal layer like Cu has become an effective solution to this problem. However, the weak CNT-Cu interfacial bonding significantly limits the mechanical and electrical performances. Here, we report that a strong CNT-Cu interface can be formed by introducing a Ni nanobuffer layer before depositing the Cu layer. The Ni nanobuffer layer remarkably promotes the load and heat transfer efficiencies between the CNT fiber and Cu layer and improves the quality of the deposited Cu layer. As a result, the new composite fiber with a 2 μm thick Cu layer can exhibit a superhigh effective strength >800 MPa, electrical conductivity >2 × 10⁷ S/m, and ampacity >1 × 10⁵ A/cm². The composite fiber can also sustain 10 000 times of bending and continuously work for 100 h at 90% ampacity.

Carbon Dots as Fillers Inducing Healing/Self-Healing and Anticorrosion Properties in Polymers

Self-healing is the way by which nature repairs damage and prolongs the life of bio entities. A variety of practical applications require self-healing materials in general and self-healing polymers in particular. Different (complex) methods provide the rebonding of broken bonds, suppressing crack, or local damage propagation. Here, a simple, versatile, and cost-effective methodology is reported for initiating healing in bulk polymers and self-healing and anticorrosion properties in polymer coatings: introduction of carbon dots (CDs), 5 nm sized carbon nanocrystallites, into the polymer matrix forming a composite. The CDs are blended into polymethacrylate, polyurethane, and other common polymers. The healing/self-healing process is initiated by interfacial bonding (covalent, hydrogen, and van der Waals bonding) between the CDs and the polymer matrix and can be optimized by modifying the functional groups which terminate the CDs. The healing properties of the bulk polymer-CD composites are evaluated by comparing the tensile strength of pristine (bulk and coatings) composites to those of fractured composites that are healed and by following the self-healing of scratches intentionally introduced to polymer-CD composite coatings. The composite coatings not only possess self-healing properties but also have superior anticorrosion properties compared to those of the pure polymer coatings.

Interlocking membrane/catalyst layer interface for high mechanical robustness of hydrocarbon-membrane-based polymer electrolyte membrane fuel cells

A physical interlocking interface that can tightly bind a sulfonated poly(arylene ether sulfone) (SPAES) membrane and a Nafion catalyst layer in polymer electrolyte fuel cells is demonstrated. Owing to higher expansion with hydration for SPAES than for Nafion, a strong normal force is generated at the interface of a SPAES pillar and a Nafion hole, resulting in an 8-fold increase of the interfacial bonding strength at RH 50% and a 4.7-times increase of the wet/dry cycling durability.

Study of Radio Frequency Plasma Treatment of PVDF Film Using Ar, O₂ and (Ar + O₂) Gases for Improved Polypyrrole Adhesion

Improvement of the binding of polypyrrole with PVDF (polyvinylidene fluoride) thin film using low pressure plasma was studied. The effects of various plasma gases i.e., Ar, O₂ and Ar + O₂ gases on surface roughness, surface chemistry and hydrophilicity were noted. The topographical change of the PVDF film was observed by means of scanning electron microscopy and chemical changes by X-ray photoelectron spectroscopy, with adhesion of polypyrrole (PPy) by abrasion tests and sheet resistance measurements. Results showed that the increase in roughness and surface functionalization by oxygen functional groups contributed to improved adhesion and Ar + O₂ plasma gave better adhesion.