Interfacial Adhesion Energy Research Articles

Effect of Star-like Polymer on Mechanical Properties of Novel Basalt Fibre-Reinforced Composite with Bio-Based Matrix.

This study is aimed at developing a fibre-reinforced polymer composite with a high bio-based content and to investigate its mechanical properties. A novel basalt fibre-reinforced polymer (BFRP) composite with bio-based matrix modified with different contents of star-like n-butyl methacrylate (n-BMA) block glycidyl methacrylate (GMA) copolymer has been developed. n-BMA blocks have flexible butyl units, while the epoxide group of GMA makes it miscible with the epoxy resin and is involved in the crosslinking network. The effect of the star-like polymer on the rheological behaviour of the epoxy was studied. The viscosity of the epoxy increased with increase in star-like polymer content. Tensile tests showed no noteworthy influence of star-like polymer on tensile properties. The addition of 0.5 wt.% star-like polymer increased the glass transition temperature by 8.2 °C. Mode-I interlaminar fracture toughness and low-velocity impact tests were performed on star-like polymer-modified BFRP laminates, where interfacial adhesion and impact energy capabilities were observed. Interlaminar fracture toughness improved by 45% and energy absorption capability increased threefold for BFRP laminates modified with 1 wt.% of star-like polymer when compared to unmodified BFRP laminates. This improvement could be attributed to the increase in ductility of the matrix on the addition of the star-like polymer, increasing resistance to impact and damage. Furthermore, scanning electron microscopy confirmed that with increase in star-like polymer content, the interfacial adhesion between the matrix and fibres improves.

Adhesive and cohesive fracture of blood clots: Experiments and modeling

Blood clots represent living materials composed of a polymer network and an abundance of cells. They might fracture within the bulk material of the clot (cohesive fracture), at the interface between the clot and the surrounding tissue (adhesive fracture), or through a combination of both modes (hybrid fracture). The clot fracture within vascular systems and injury sites could lead to life-threatening conditions. Despite the significance, understanding and modeling the fracture behaviors of blood clots, including their dependence on mechanical loading and cellular components, remain in a nascent stage. In this study, we employ an integrated experimental-computational approach to comprehensively investigate the fracture behaviors of bovine blood clots. We explore various mechanical factors, substrates, and cellular components such as red blood cells (RBCs) and platelets. Our findings reveal that among various tissue substrates, blood clots exhibit the highest interfacial adhesion energy with muscle, and the lowest to the inner arterial lining, consistent with their biological function. Both interfacial adhesion energy and bulk fracture energy are rate-dependent, although they exhibit different dependencies. Also, RBCs and platelets have different effects on clot fracture. An increase in RBC content tends to toughen both adhesion and fracture of blood clots. However, an increase in platelet content enhances interfacial adhesion energy but lowers the bulk fracture energy. The platelet content also governs the shift from adhesive fracture to hybrid fracture. To model clot fracture, we developed two finite element models incorporating a coupled cohesive-zone and Mullins-effect approach to simulate pure shear fracture and peeling of blood clots. These models, validated through experimental data, elucidate the interplay between intrinsic fracture toughness, interfacial strength, and bulk energy dissipation during clot fracture. This study significantly advances our understanding of clot mechanics, providing valuable insights into the mechanics of similar living materials and the management of clot-related disorders such as hemorrhage and thrombosis.

Probing the Effect of Alloying Elements on the Interfacial Segregation Behavior and Electronic Properties of Mg/Ti Interface via First-Principles Calculations.

The interface connects the reinforced phase and the matrix of materials, with its microstructure and interfacial configurations directly impacting the overall performance of composites. In this study, utilizing seven atomic layers of Mg(0001) and Ti(0001) surface slab models, four different Mg(0001)/Ti(0001) interfaces with varying atomic stacking configurations were constructed. The calculated interface adhesion energy and electronic bonding information of the Mg(0001)/Ti(0001) interface reveal that the HCP2 interface configuration exhibits the best stability. Moreover, Si, Ca, Sc, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, Mo, Sn, La, Ce, Nd, and Gd elements are introduced into the Mg/Ti interface layer or interfacial sublayer of the HCP2 configurations, and their interfacial segregation behavior is investigated systematically. The results indicate that Gd atom doping in the Mg(0001)/Ti(0001) interface exhibits the smallest heat of segregation, with a value of -5.83 eV. However, Ca and La atom doping in the Mg(0001)/Ti(0001) interface show larger heat of segregation, with values of 0.84 and 0.63 eV, respectively. This implies that the Gd atom exhibits a higher propensity to segregate at the interface, whereas the Ca and La atoms are less inclined to segregate. Moreover, the electronic density is thoroughly analyzed to elucidate the interfacial segregation behavior. The research findings presented in this paper offer valuable guidance and insights for designing the composition of magnesium-based composites.

Thermodynamic properties, interfacial adhesion energy and tribological properties between MCN (M = Hf, Ta, Cr, Nb) coating and Ti alloy substrates investigated by experiment and first-principles calculations

A series of MCN (M = Hf, Ta, Cr, Nb) coatings were prepared by double glow plasma surface alloying (DGPSA) as protective hard coatings for Ti60 (Ti-5.5Al-4.0Zr-4.0Sn), aiming to solve the problems of low bonding strength between the ceramic coating and the substrate as well as the poor wear resistant of ceramic alloy coatings. First principles calculation was used to study the elastic constant of MC0.5N0.5 solids, thermomechanical parameters and the interfacial adhesive strength of Ti(101)/MCN(220). The calculated results indicated the HfCN solids show excellent mechanical properties, lower thermal expansion coefficient α, lower Gibbbs values and higher values of entropy (S), superior adhesion strength Wad ∼ 5.7 J/m2. The high-temperature tribological performance tests show that the HfCN and TaCN coatings exhibited better wear resistance compared with the CrCN and NbCN coatings at 500 °C -700 °C. The wear rate of HfCN coatings at 500 °C and 700 °C is about 2 times and 5 times lower than that of CrCN, which is in accordance with the HfCN coating’s excellent thermal stability and high interfacial bonding strength with the Ti substrate. The adhesion wear mechanism of all coatings gradually intensified with increasing temperature.

Highly stable silicon oxycarbide all-solid-state batteries enabled by machined learning accelerated screening of oxides and sulfides electrolytes

Traditional trial–error approach severely limits and restricts rapid development of high-performance anode and electrolytes materials, searching huge parameters space of various anode-solid electrolyte interfaces in an effective and efficient way is the key issue. Here, a novel computational strategy combining machine learning and first-principles is proposed to achieve efficient high-throughput screening of oxides and sulfides electrolytes for highly stable silicon oxycarbide all-solid-state batteries. First-principles calculations demonstrate significant compact of material type and elemental doping on interfacial compatibility between silicon oxycarbide and various electrolytes. By proposing several novel descriptors including interfacial adhesion and formation energies of frozen system with low computation cost, the amounts of demanded trainings data are significantly reduced. Gradient-boosted regression tree model shows low mean absolute errors of 0.09 and high R2 value of 0.99 for the prediction of interface formation energy, demonstrating ultrahigh accuracy and reliability of the algorithm. The present work discovers a series of uninvestigated stable anode-solid electrolytes interfacial couples for further experimental preparation.

Electronic structure, bonding, and mechanical strength at the [formula omitted]-Al2O3 (0001)/L12-Al3Zr (111) interface by first-principles calculations

The interface adhesion energy, interfacial energy, charge density difference, local density of states, and first-principles computational tensile test of α-Al2O3 (0001)/L12-Al3Zr (111) interface were investigated by first-principles calculations. The dominant factors affecting the interfacial bond strength are the type of chemical bonds and the number of electronic orbital hybrids at the interface. The first-principles computational tensile test demonstrates that Al-fcc and Al2-hcp configurations fracture at the interface, while the O-fcc configuration fractures at the Al3Zr slab rather than at the interface and has the best tensile strength. The proposed interface bonding criteria were based on the analysis of the Al2O3/Al3Zr interface bonding data. These criteria will guide the establishment of the interface model. These results will provide theoretical guidance for understanding the failure mechanism of the Al2O3/Al3Zr interface and designing new interfaces.

Molecular dynamics simulation of interfacial mechanical properties of crumb rubber concrete

Crumb rubber concrete is a new type of cement concrete made from waste rubber as partial aggregate. The mechanical properties and resistance to cracking of crumb rubber concrete are not only related to the mechanical properties of each constituent phase, but also closely related to the interface characteristics and interactions between the cement paste and rubber/aggregate. This article uses molecular dynamics simulation to analyze the two characteristic interfaces (coarse aggregate/cement paste, rubber/cement paste) in the micro and nano structures of crumb rubber concrete at the molecular scale. By simulating the indentation process, interfacial adhesion energy, and interfacial pull-out performance, the micro mechanical properties and mechanisms of different interfaces were further compared and analyzed. From the simulation results, it can be seen that the C-S-H/calcite interface is mainly composed of ion bonds, with the highest interaction force. The C-S-H/silica interface is mainly composed of hydrogen bonds, while the C-S-H/rubber interface is mainly composed of van der Waals force, with the lowest interaction force. The C-S-H/calcite interface has the highest adhesion energy, while the C-S-H/rubber interface has the lowest adhesion energy. In interface indentation simulation, calcite has the greatest impact on C-S-H, while rubber has the smallest impact on C-S-H.

Effects of surface treatments for the adhesion improvement between Cu and SiCN in BEOL interconnect

This study focuses on the enhancement of interfacial reliability between Cu interconnects and silicon carbon nitride (SiCN) capping layers in semiconductor packaging structures through pre-deposition surface treatments. We compare three distinct treatments combined with H2 plasma, NH3 plasma, and SiH4 gas inflow, evaluating their effectiveness through quantitative measurement of interfacial adhesion energy using a double cantilever beam (DCB) fracture mechanics test. The results exhibit a remarkable adhesion energy improvement of over 1150 % with the addition of SiH4 gas treatment. Thorough investigations reveal that the mechanism of the exceptional adhesion enhancement is attributed to unique chemical bonding and fracture behavior. In other words, Si atoms in the SiH4 gas treatment incorporate onto Cu surfaces with specific crystallographic orientations, resulting in significantly stronger Cu–Si bonding in selective regions compared to other bondings. Moreover, the crystallographic-orientation-dependent bonding characteristic induces crack kinking at grain boundaries, dissipating the crack propagation energy. This work will provide crucial insight into enhancing the interfacial reliability and manufacturing yield of semiconductor devices.

Iron Tailings as Mineral Fillers and Their Effect on the Fatigue Performance of Asphalt Mastic.

Incorporating iron tailings (ITs) into asphalt represents a new method for waste-to-resource conversion. The objective of this study is to evaluate the fatigue performance of ITs as fillers in asphalt mastic and investigate the interaction and interfacial adhesion energy between asphalt and ITs. To achieve that, the particle size distributions of two ITs and limestone filler (LF) were tested through a laser particle size analyzer; the morphology and structure characteristics were obtained by scanning electronic microscopy (SEM), the mineral compositions were conducted through X-ray diffraction (XRD), and the chemical compositions were tested through X-ray Fluorescence Spectrometer (XRF). Furthermore, the fatigue properties of asphalt mastic and the interaction between asphalt binder and mineral fillers (ITs and LFs) were evaluated by Dynamic Shear Rheometer (DSR). The interfacial adhesion energy between ITs and asphalt binder were calculated through molecular dynamics simulation. In the end, the correlation between the test results and the fatigue life is established based on the gray correlation analysis, the environmental and economic benefits of iron tailings asphalt pavement are further evaluated. The results show that the particle size distribution of ITs is concentrated between 30 μm and 150 μm, and the main component is quartz. ITs have rich angularity and a higher interaction ability with asphalt. The adhesion energy of iron tailings filler to asphalt is less than that of limestone. The correlation degree of the interfacial adhesion energy and interaction between asphalt and mineral filler with asphalt mastic fatigue life is close to 0.58. Under the combined action of interaction ability and interfacial adhesion energy, the fatigue life of IT asphalt mastic meets the requirements. ITs as a partial replacement for mineral fillers in asphalt pavement have great environmental and social effectiveness.

In Situ Structural Densification of Hydrogel Network and Its Interface with Electrodes for High-Performance Multimodal Artificial Skin.

The multisensory responsiveness of hydrogels positions them as promising candidates for artificial skin, whereas the mismatch of modulus between soft hydrogels and hard electrodes as well as the poor adhesion and conductance at the interface greatly impairs the stability of electronics devices. Herein, we propose an in situ postprocessing approach utilizing electrochemical reactions between metals (Zn, etc.) and hydrogels to synergistically achieve strong adhesion of the hydrogel-electrode interface, low interfacial impedance, and local strain isolation due to the structural densification of the hydrogel network. The mechanism is that Zn electrochemically oxidizes to Zn2+ and injects into the hydrogel, gradually forming a mechanically interlocked structure, Zn2+-polymer dual-helix structural nodes, and a high-modulus ZnO from the surface to the interior. Compared to untreated samples, the treated sample displays 8.7 times increased interfacial adhesion energy between the hydrogel and electrode (87 J/m2), 95% decreased interfacial impedance (218.8 Ω), and a high-strain isolation efficiency (εtotal/εisolation > 400). Akin to human skin, the prepared sensor demonstrates multimodal sensing capabilities, encompassing highly sensitive strain perception and simultaneous perception of temperature, humidity, and oxygen content unaffected by strain interference. This easy on-chip preparation of hydrogel-based multimodal sensor array shows great potential for health and environment monitoring as artificial skin.

Insights into the effects of La on the grain refinement and mechanical properties of Al-Ti-C intermediate alloy and pure Al: A first-principle study and experimental investigation

This paper employs the self-propagating high-temperature synthesis (SHS) to prepare Al-Ti-C master alloys and explores the effects of integrating the rare earth element lanthanum to create Al-Ti-C-La composites. This research focuses on the microstructural changes in both the master alloy and pure aluminum, which aimed to elucidate the mechanisms that enhance grain refinement and resistance to grain refinement fading. The analysis reveals that when Al-Ti-C-La master alloys are incorporated into molten Al, the predominant structures formed include an Al matrix, rod-like Al3Ti phases, and TiC particles, alongside AlLa phases and substantial Al20Ti2La compounds. The grain refining capability of Al-Ti-C-La master alloys is significantly exceeds that of the Al-Ti-C master alloys. The addition of La markedly reduces the settling of TiC particles, thereby granting the Al-Ti-C-La master alloys excellent resistance to grain refinement fading. The newly formed Al20Ti2La phase plays a crucial role in refining the aluminum matrix, with metallic bond characteristics present on the side towards the Al matrix at the Al20Ti2La/Al interface and distinct covalent bond characteristics on the Al20Ti2La side. Moreover, the Al20Ti2La (110)/Al (110) interface exhibits the highest interfacial adhesion energy and stronger covalent bond features. Consequently, α-Al is prone to heterogeneously nucleate on the Al20Ti2La phase via the Al20Ti2La (110)/Al (110)-HCP orientation, which refines the grains of the aluminum matrix, ultimately enhancing the performance of aluminum-based alloys.

Biocompatible Tough Ionogels with Reversible Supramolecular Adhesion.

Cohesive and interfacial adhesion energies are difficult to balance to obtain reversible adhesives with both high mechanical strength and high adhesion strength, although various methods have been extensively investigated. Here, a biocompatible citric acid/L-(-)-carnitine (CAC)-based ionic liquid was developed as a solvent to prepare tough and high adhesion strength ionogels for reversible engineered and biological adhesives. The prepared ionogels exhibited good mechanical properties, including tensile strength (14.4 MPa), Young's modulus (48.1 MPa), toughness (115.2 MJ m-3), and high adhesion strength on the glass substrate (24.4 MPa). Furthermore, the ionogels can form mechanically matched tough adhesion at the interface of wet biological tissues (interfacial toughness about 191 J m-2) and can be detached by saline solution on demand, thus extending potential applications in various clinical scenarios such as wound adhesion and nondestructive transfer of organs.

Multi-scale analysis and structural application of the synergistic enhancement effect of silane coupling agent on the interface between PVA/rubber and cement

This study employs polyvinyl alcohol (PVA) fibers and silane coupling agent (SCA) to augment rubberized concrete mechanical prowess. A multiscale investigation delves into the synergistic enhancement mechanism of SCA on the interfaces of PVA/cement and rubber/cement, considering macroscopic mechanical properties, microscopic structural characteristics, and nanoscale interface interactions. Initially, fundamental mechanical performance tests reveal a notable enhancement in compressive and flexural strength with the inclusion of SCA and PVA fibers in rubberized concrete. Subsequently, observations of corresponding composite concrete slices are conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The results manifest gel and polymer filling interface gaps, with SCA fostering a tighter amalgamation of the two interfaces, effectively rectifying interface defects and elucidating its bonding effects at the microscopic interface. Molecular dynamics (MD) modeling and simulation analyses of PVA/C-S-H and rubber/C-S-H, pre- and post-SCA modification, demonstrate that SCA mitigates interface effects, reinforcing hydrogen bonding, van der Waals interactions, Ca-H coordination bonds, and stability. This augmentation enhances interface adhesion energy, fortifying the weak interface bonding between PVA fibers, rubber, and inorganic silicate (C-S-H). Ultimately, portal frame experiments substantiate that incorporating fiber rubberized concrete into structures not only fails to diminish but marginally enhances the load-bearing capacity of the framework. This research furnishes concrete and innovative solutions for sustainable development while providing a valuable reference for the future application of PVA fiber rubberized concrete materials in practical engineering endeavors.

The Role of Surface Free Energy in Binder Distribution and Adhesion Strength of Aqueously Processed LiNi0.5Mn1.5O4 Cathodes

This study identifies the critical aspects of binder distribution and mechanical integrity in aqueously processed LNMO cathodes, employing a comprehensive approach involving surface characterization techniques, adhesion strength testing, and electrochemical characterization. The investigation includes the use of the Washburn and Sessile Drop methods for surface free energy analysis, revealing key insights into the interfacial free energy of adhesion between cathode constituents. The results explain the formation of carbon-binder-domains and their impact on adhesion strength, with a particular focus on the conductive additives’ (CA) surface area. The study demonstrates the effectiveness of reducing CA surface area and employing alternative conductive additives, such as vapor-grown carbon fibers (VGCF), in improving adhesion strength and mitigating capacity fade attributed to delamination during cycling. Furthermore, the research emphasizes the role of heat treatment beyond the melting point of the polyvinylidene fluoride (PVDF) latex binder, showcasing its influence on wetting and enhancing mechanical integrity. The presented methodology provides a valuable tool for predicting and optimizing binder distribution, offering insights into improving the overall performance and reliability of aqueously processed cathodes for advanced lithium-ion batteries.

On the Disproportionate Contribution of Membrane Electron Donor Functionality in Membrane Biofouling.

This study set out to uncover which interfacial properties have the greatest impact on membrane organic fouling, biofouling, and fouling resistance. A relatively simple manipulation of the basic equations used in determining Lifshitz-van der Waals (LW) and Lewis acid-base (AB) surface tensions for solid materials reveals that the high electron accepticity of water makes the electron donicity of membrane and biofouling materials the key component governing their interfacial free energy of adhesion (ΔG132), which defines the favorability (or unfavorability) of one material (1) adhering to another (2) when immersed in a liquid (3). Various biofoulant and membrane LW and AB surface tensions were systematically characterized. Static bacterial adhesion, alginic acid filtration, and wastewater filtration tests were conducted to determine the fouling propensities of three different polymeric membrane materials. Experimental results of microbial adhesion, alginate fouling, and biofouling tests all correlated well with membrane electron density, where higher electron density produced less organic fouling or biofouling. These combined theoretical and experimental results confirm the importance of surface electron donicity in determining the fouling propensity of polymeric membranes.

Influence of chloride salt erosion on the adhesion of asphalt-aggregate interfaces considering mineral anisotropy: insights from molecular dynamics.

Asphalt, a polymer mixture composed of various hydrocarbons, is extensively utilized due to its excellent performance. To evaluate the sensitivity of asphalt concrete to chloride salt damage at the nanoscale, considering the anisotropy of aggregate mineral crystal orientation, molecular dynamic simulations were employed to model the interface interactions between asphalt and aggregate mineral components (silica and calcite) under chloride salt exposure. The wetting processes of water droplets and chloride salt droplets on different crystal surfaces of silica and calcite were analyzed. Furthermore, the adhesive energy, decohesion energy, degradation ratio, and energy ratio of the interaction model between asphalt and aggregate mineral interfaces were analyzed to reveal the variations in the interfaces between the two components. The results demonstrated that the anisotropy of the minerals significantly affects the adhesion energy of asphalt and aggregate. Moreover, the surface hydrophilicity of calcite was larger than that of silica. The interfacial adhesion energy of asphalt-calcite was larger than that of asphalt-silica under dry condition and chloride salt attack, and the interfacial adhesion energy of both asphalt and mineral decreased with the increase of chloride salt concentration. The degradation ratio and energy ratio values of asphalt and calcite were larger than those of asphalt and silica, and the anisotropy of the mineral surface affected the degradation ratio and energy ratio values. This study provides a new method and theoretical basis for further research on the damage mechanism and strengthening measures of asphalt-aggregate under chloride salt attack. To investigate the interaction between asphalt and mineral aggregates under chloride salt erosion, models of asphalt, aggregate, and asphalt/aggregate composite systems were constructed using the Amorphous Cell module in Materials Studio 2020 software. Molecular dynamic simulations of the asphalt/aggregate composite system were then conducted using the Forcite module, employing the COMPASS II force field to describe atomic and molecular interactions. Initially, considering the crystal orientation and surface configuration of the aggregate minerals, the impact of mineral anisotropy on the asphalt-aggregate interface model was analyzed. Subsequently, by simulating the contact states of nano water droplets and chloride salt droplets with different mineral surfaces, the wetting characteristics of nano water droplets on silica and calcite surfaces were determined. Lastly, considering the corrosion effect of chloride solution at different concentrations, the adhesion energy, debonding energy, degradation ratio, and energy ratio of the asphalt-aggregate interface interaction model were analyzed.

High-Toughness CO2-Sourced Ionic Polyurea Adhesives.

Polyurea (PUa) adhesives are renowned for their exceptional adhesion to diverse substrates even in harsh environments. However, the presence of quadruple bidentate intermolecular hydrogen bonds in the polymer chains creates a trade-off between cohesive energy and interfacial adhesive energy. To overcome this challenge, a series of CO2-sourced ionic PUa adhesives with ultratough adhesion to various substrates are developed. The incorporated ionic segments within the adhesive serve to partially mitigate the intermolecular hydrogen bonding interactions while conferring unique electrostatic interactions, leading to both high cohesive energy and interfacial adhesive energy. The maximum adhesive strength of 10.9MPa can be attained by ionizing the CO2-sourced PUa using bromopropane and subsequently exchanging the anion with lithium bis(trifluoromethylsulfonyl)imide. Additionally, these ionic PUa adhesives demonstrate several desirable properties such as low-temperature stability (-80°C), resistance to organic solvents and water, high flame retardancy, antibacterial activity, and UV-fluorescence, thereby expanding their potential applications. This study presents a general and effective approach for designing high-strength adhesives suitable for a wide array of uses.

Adhesion properties of MoS<sub>2</sub>/SiO<sub>2 </sub>interface: Size and temperature effects

The interface adhesion properties are crucial for designing and fabricating two-dimensional materials and related nanoelectronic and nanomechanical devices. Although some progress of the interface adhesion properties of two-dimensional materials has been made, the underlying mechanism behind the size and temperature dependence of interface adhesion energy and related physical properties from the perspective of atomistic origin remain unclear. In this work, we investigate the effects of size and temperature on the thermal expansion coefficient and Young’s modulus of MoS<sub>2</sub> as well as interface adhesion energy of MoS<sub>2</sub>/SiO<sub>2</sub> based on the atomic-bond-relaxation approach and continuum medium mechanics. It is found that the thermal expansion coefficient of monolayer MoS<sub>2</sub> is significantly larger than that of its few-layer and bulk counterparts under the condition of ambient temperature due to size effect and its influence on Debye temperature, whereas the thermal expansion coefficient increases with temperature going up and almost tends to a constant as the temperature approaches the Debye temperature. Moreover, the variations of bond identity induced by size effect and temperature effect will change the mechanical properties of MoS<sub>2</sub>. When the temperature is fixed, the Young’s modulus of MoS<sub>2</sub> increases with size decreasing. However, the thermal strain induces the volume expansion, resulting in the Young’s modulus of MoS<sub>2</sub> decreasing. Furthermore, the size and temperature dependence of lattice strain, mismatch strain of interface, and Young’s modulus will lead the van der Waals interaction energy and elastic strain energy to change, resulting in the change of interface adhesion energy of MoS<sub>2</sub>/SiO<sub>2</sub>. Noticeably, the interface adhesion energy of MoS<sub>2</sub>/SiO<sub>2</sub> gradually increases with MoS<sub>2</sub> size decreasing, while the thermal strain induced by temperature causes interface adhesion energy of MoS<sub>2</sub>/SiO<sub>2</sub> to decrease with temperature increasing. In addition, we predict the conditions of the interface separation of MoS<sub>2</sub>/SiO<sub>2</sub> under different sizes and temperatures. Our results demonstrate that increasing both size and temperature can significantly reduce the interface adhesion energy, which is of great benefit in detaching MoS<sub>2</sub> film from the substrate. Therefore, the proposed theory not only clarifies the physical mechanism regarding the interface adhesion properties of transition metal dichalcogenides (TMDs) membranes, but also provides an effective way to design TMDs-based nanodevices for desirable applications.

Interfacial mechanical properties of graphene on randomly rough PET substrate surface: A molecular dynamics study

In this work, molecular dynamics (MD) simulations are performed to create a series of polyethylene terephthalate (PET) substrates with random roughness, and the morphological characteristics and interfacial bonding of graphene on the real rough PET surface are first simulated. The results show that the interfacial mechanical behavior of graphene freely adhered to the PET roughness is influenced by the surface profile. Besides causing the non-conformal contact, the rough surface hinders the propagation of bending waves from the graphene corner regions during the adhesion and weakens their overlap. The increased surface roughness weakens interfacial adhesion and inhibits interfacial sliding, leading to the formation of larger morphological defects such as wrinkles. Furthermore, the measurement of the interfacial adhesion energy of graphene/PET substrate is achieved by the shaft loaded blister test (SLBT), which for the first time is used to simulate the interfacial debonding of graphene on rough PET surfaces. For low surface roughness, interfacial adhesion dominates the debonding behavior and the blister boundary preferentially extends along the interfacial defect area. For high surface roughness, the increasingly serious non-conformal contact makes the blister more likely to instability and enter the stage where normal and shear interactions are coupled.

Molecular dynamics models to investigate the diffusion behavior of emulsified asphalt

The utilization of emulsified asphalt is widespread in the recycling of asphalt pavement due to its eco-friendliness and energy efficiency. While numerous research studies have been conducted on the mixture design and strength assessment of emulsified asphalt, the mechanism by which it diffuses and adheres to the aggregate surface remains inadequately comprehended. This study developed molecular dynamics models to investigate the diffusion behavior of emulsified asphalt on the aggregate surface to clarify the role of emulsifier, water, and asphalt in the adsorption process from a molecular perspective. Interface models are established according to the diffusion state for interfacial adhesion evaluation. The results show that the movement of water molecules is the driving force for the entire emulsified asphalt to adsorb to the aggregate surface, whether the aggregate is silica or reclaimed asphalt pavement (RAP). Compared with anionic surfactant Sodium Dodecylbenzene Sulfonate (SDBS), cationic emulsifier Cetyltrimethylammonium Chloride (CTAC) has a better affinity, stronger adsorption, and higher interfacial adhesion energy with silica. Compared with RAP, emulsified asphalt is more readily adsorbed to the surface of silica. It is concluded that emulsifiers have two distribution conformations during the adsorption process, delamination, and aggregation, with delamination exhibiting stronger interface strength with silica than aggregation. When the emulsified asphalt spreads on the RAP surface, the penetration of water molecules into the aged asphalt layer in the RAP structure reduces the structure's water resistance. These results can provide a molecular perspective for understanding the internal structure of emulsified cold recycle mixture (ECRM) and link the adsorption behavior of emulsified asphalt on aggregate surfaces with the internal interface strength of ECRM.