Polyimide (PI) based tribological composites are widely used in demanding engineering environments, where combined heat and humidity may significantly deteriorate their surface stability and wear resistance. In this work, TiO2 reinforced PI/carbon fiber (PI/CF) composites were prepared to investigate their tribological behavior under hygrothermal ageing conditions. Accelerated ageing experiments (90 degrees C, 95% RH) were performed to evaluate moisture absorption characteristics, thermal stability, surface chemical evolution, and tribological performance of the composites. The results indicate that the incorporation of TiO2 effectively suppresses moisture uptake and improves the stability of the load-bearing surface during sliding. Among the investigated compositions, the composite containing 5 wt% TiO2 exhibits the best tribological performance after ageing, with the wear rate reduced by 49.3% compared with the TiO2 free composite. Morphological observations reveal that a moderate TiO2 content promotes the formation of a mechanically stable sliding interface, whereas excessive TiO2 leads to particle agglomeration and surface damage. To further elucidate the underlying mechanisms, molecular dynamics simulations were conducted to analyze the structural evolution of aged PI systems with different TiO2 contents. The simulation results demonstrate that an intermediate TiO2 content reduces free volume, enhances cohesive energy density, and restricts polymer chain mobility, which contributes to improved resistance against hygrothermal degradation. The combined experimental and molecular dynamics analysis provides new insights into the tribological durability of PI based composites in harsh hygrothermal environments.

Surface and interface science play an important role in the tribological properties of materials. Recently, research in this field has extended from the macroscopic scale to the molecular level to elucidate energy dissipation and structural evolution mechanisms at sliding interfaces. In this work, we propose a nanolubricant strategy based on carbon nanocages (CNCs). Three types of lubricating molecules—oleylamine (amine), oleic acid (carboxyl), and stearyl alcohol (hydroxyl)—were encapsulated into a polytetrafluoroethylene (PTFE) matrix to construct a composite tribological interface model. Molecular dynamics simulations were employed to investigate the interfacial enrichment, diffusion, and interaction mechanisms of these molecules with PTFE chains and the Fe counterface. Particular emphasis was placed on how different functional groups regulate energy transfer and dissipation pathways. This study deepens the molecular–level understanding of structure–lubrication relationships and provides theoretical guidance for designing high–performance polymer–based tribological materials.

To reveal the friction and wear mechanisms between different friction pairs in ultrasonic motors (USM), this study employed molecular dynamics (MD) simulation methods to systematically compare four typical friction pair models: T1 (Al2O3-PTFE/CuO), T2 (Al2O3/GO-PTFE/CuO), T3 (Al2O3-PI/CuO), and T4 (Al2O3/GO-PI/CuO). In these models, Al2O3 and Al2O3/GO served as the rotors, and the friction materials of polytetrafluoroethylene (PTFE) and polyimide (PI) on the surface of CuO acted as the stators. Through the micro-arc oxidation (MAO) technique, graphite oxide (GO) was in-situ compounded in the aluminum oxide (Al2O3). The interaction energy, friction coefficient, interface temperature, and sliding stability of different friction pairs were calculated as key parameters through MD simulation. Experimental results showed that the introduction of GO could significantly enhance the interfacial bonding strength and thermal conductivity of each system. Comprehensive comparison revealed that the T2 exhibited the most excellent comprehensive performance, with the lowest friction coefficient, the smallest interface temperature rise, and the most stable friction. This indicates that the in-situ compound of GO during the MAO process of the aluminum alloy rotor of the USM is the most ideal choice. The improved mechanism was revealed by MD simulation and experiments. This study clarified the performance differences between different friction pairs at the atomic scale, providing an important theoretical basis for the design of friction pairs in USM under different working conditions.

The development of polymer composite coatings that simultaneously exhibit efficient frictional heat dissipation and superior tribological performance has faced a significant challenge in engineering applications. While several preliminary solutions exist, many operational scenarios still necessitate a difficult compromise between high thermal conductivity and wear resistance. This highlights a pressing need for innovation in fundamental design strategies to achieve a breakthrough. In this study, we integrated porous copper films fabricated using the dynamic hydrogen bubble template (DHBT) method with polyimide (PI) for the first time to create a metal/polymer 3D interpenetrating composite coating. The resulting material demonstrates not only a substantial enhancement in thermal conductivity (~4.4W/(m·K), corresponding to an increase of ~200% relative to PI coating) but also a reduced wear rate of ~2.18 × 10-5 mm3/(N·m), representing a reduction of ~56% compared to pure PI. Experimental characterization and molecular dynamics simulations reveal that this outstanding performance mainly originates from the continuous porous copper framework and the synergistic lubrication characteristics of copper nanoparticles released during friction and the transfer film. This work not only offers fresh perspectives on designing high-thermal-conductivity wear-resistant coatings, but also opens unique avenues for multifunctional coating development through the perspective of spatial structure.

This study addresses the mechanical and tribological performance deficiencies of borophenolic resin (BPF)-based frictional materials by surface-modifying hexagonal boron nitride (h-BN) with polydopamine (PDA). Composites with 6-10 wt% h-BN@PDA were prepared to systematically evaluate the interfacial effects. The PDA layer improves h-BN dispersion and interfacial bonding, thereby enhancing hardness, impact strength, and thermal conductivity. At the optimal 8 wt% loading, the wear rate reaches 4.76 & times; 10-6 mm3/N m, a 54.62% reduction compared to the unmodified h-BN. This study confirms the effectiveness of PDA surface modification in enhancing the mechanical-thermal-tribological synergy of BPF-based composites, providing new insights for the design of high-performance polymer-based frictional materials.

High-precision in situ monitoring of tribological interface temperature is essential for the reliable operation of aerospace and advanced tribological systems, yet conventional thermocouples and infrared methods suffer from implantation difficulties, delayed response, and environmental interference. Here, we report a novel multifunctional lubricated nanocapsule that leverages the phase-change behavior of deep eutectic solvents (DES) to overcome these limitations. Structural characterization was performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy, and tribological tests were conducted to evaluate both tribological behavior and capacitance-temperature response mechanisms. Experimental results demonstrate that when the interface temperature reaches the melting point of the DES, the capacitance of the tribological system undergoes an abrupt transition, while both the coefficient of friction (COF) and the wear rate decrease to a certain extent. The improvement in dielectric properties is ascribed to the ion polarization effect generated by the molten DES, whereas the enhancement of tribological performance arises from the lubrication protection provided by its liquid phase. This work demonstrates a materials-based strategy for real-time temperature sensing at dynamic tribological interfaces, offering new opportunities for intelligent lubrication and fault prediction in high-end equipment.

The chemical structure of lubricant molecules dictates their adsorption behavior, orientation, and energy dissipation pathways at tribological interfaces, playing a pivotal role in system performance. In this study, lubricant molecules with varying functional groups were encapsulated within carbon nanocages (CNCs) and incorporated into a polymer matrix to construct a novel self-lubricating coating. The microstructure and chemical composition were characterized using Field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). Combined with molecular dynamics (MD) simulations, the interfacial behaviors and evolutionary mechanisms of the lubricants were systematically elucidated, establishing a multiscale correlation between molecular structure, interfacial interactions, and macroscopic tribological performance. Experimental results demonstrate that the oleic acid (OA) system exhibits superior tribological performance, attributed to the stable interaction network formed by its carboxyl (-COOH) group with both the polymer matrix and the metal surface. In contrast, the stearyl alcohol (SA) system primarily relies on weak physical adsorption. Furthermore, due to its solid state at ambient temperature, SA lacks the capacity for continuous dynamic replenishment at the interface, leading to inferior stability. This work elucidates the atomic-scale role of molecular chemistry at tribological interfaces, providing a theoretical foundation for the rational design of high-performance self-lubricating coatings in engineering applications.

ABSTRACT Polyimide (PI)‐based tribological composites containing carbon fiber (CF), molybdenum disulfide (MoS 2 ), and other solid lubricants have been extensively studied. However, the role of hexagonal boron nitride (h‐BN) in regulating interfacial interactions and wear mechanisms in PI/CF/MoS 2 systems remains insufficiently understood. In this study, the effects of h‐BN incorporation on the mechanical and tribological behaviors of PI/CF/MoS 2 composites were systematically investigated through experimental characterization combined with molecular dynamics (MD) simulations. The results revealed that h‐BN addition improved hardness while reducing tensile strength and ductility due to the enhanced interfacial restriction and increased stress concentration. The tribological performance exhibited a non‐monotonic dependence on h‐BN content, with the optimal performance achieved at 5 wt.% h‐BN. Scanning electron microscopy (SEM) and energy‐dispersive X‐ray spectroscopy (EDS) analyses suggested that an appropriate h‐BN content facilitated the formation of a relatively continuous transfer film, whereas excessive h‐BN promoted filler agglomeration and interfacial degradation, leading to accelerated wear. Furthermore, MD simulations suggested that the reduced molecular mobility and fractional free volume at the optimal h‐BN content were consistent with enhanced interfacial stability. The combined experimental and simulation results provide qualitative insights into the role of h‐BN in regulating filler dispersion, interfacial interactions, and molecular chain dynamics. These findings establish a structure–property relationship for designing high‐performance multi‐filler PI‐based tribological composites.

Adhesive technology is crucial for the assembly and reliability of engineered systems, such as ultrasonic motors used in aerospace environments, where adhesives must maintain high shear strength and thermal stability. This study investigated the temperature-dependent properties of adhesive layers in ultrasonic motors using a combination of experimental testing and molecular dynamics (MD) simulations. Four adhesive systems were prepared using two epoxy resins-resorcinol diglycidyl ether (RDGE) and 4,4-diaminodiphenylmethane tetraglycidylamine (TGDOM)-and two curing agents-m-cyclohexanedimethylamine (HXDA) and polyetheramine (D230). The results showed that the RDGE-D230 system exhibited the highest adhesive strength and was therefore selected for further analysis. Shear tests were conducted on the stator-piezoelectric ceramic interface and the rotor-friction material interface within a temperature range of 220-380 K. The results show that the shear strength decreases significantly with increasing temperature. The shear strength at the stator-ceramic interface decreases from 5.26 MPa at 220 K to 0.9 MPa at 340 K, and the shear strength at the rotor-friction material decreases from 4.96 MPa at 220 K to 0.53 MPa at 340 K. Molecular dynamics simulations indicate that increasing temperature enhances molecular mobility in the adhesive layer, and the fracture mode changes from brittle fracture to ductile fracture, manifested as an increase in mean square displacement and radius of gyration (from 8 & Aring; to 10.5 & Aring;). Simultaneously, the interaction energy between the adhesive and the substrate decreases with increasing temperature. These results elucidate the molecular mechanism of temperaturedependent adhesion and provide guidance for adhesive selection in high-temperature applications.

This study explores the hygrothermal aging resistance of graphene nanosheet (GN)‐reinforced epoxy composites via a combined experimental and molecular dynamics (MD) simulation approach. Epoxy systems with 0–1.0 wt% GN are fabricated and aged at 80 °C for 516 h. Optimal performance is achieved at 0.75 wt% GN, exhibiting improved tensile strength, impact toughness, hardness, and glass transition temperature. GN addition reduces moisture uptake and diffusion by physically obstructing water pathways and restricting chain mobility. Scanning electron microscopy analysis shows suppressed crack formation, while MD simulations reveal that GN enhanced interfacial bonding, decreases fractional free volume, reduces mean square displacement, and limits water‐induced hydrogen bonding. Notably, GN increases interfacial interaction energy by up to 96.4% relative to water–epoxy bonding. These results demonstrate a multiscale reinforcement mechanism and offer a rational strategy for designing durable epoxy composites for aerospace and electronic packaging applications.

The accumulation of frictional heat significantly influences the tribological properties of polymeric materials. However, the microscopic mechanism underlying its generation remains unclear, which poses a major obstacle to the investigation and development of polymer-based friction materials. To address this, we investigated the frictional heating behavior of polymers using molecular dynamics simulations. The results reveal that the conversion between potential and kinetic energy, driven by the aperiodic conformational fluctuations of polymer molecular chains, contributes to the continuous generation of frictional heat. Building on this finding, we further examined the microscopic mechanisms by which various friction conditions-namely, sliding velocity, contact pressure, and ambient temperature-affect thermogenesis. This study not only establishes a theoretical foundation for the design and development of advanced polymer friction materials but also offers potential insights for the development of thermal management strategies in polymer-based friction systems.

In order to reveal the enhancement mechanism of carbon nanotube (CNT) and graphene (Gr) on polytetrafluoroethylene (PTFE) at the atomic scale, atomic molecular (AA) dynamics and coarse-grained (CG) method were combined to investigate their mechanical and tribological performance. Firstly, the influence of model size, mapping scheme and reinforcing material on the mechanical properties of PTFE was studied by tensile simulation. The results show that the size of the model will affect the accuracy of the material performance. The larger the model, the more accurate the simulation results. The larger the number of atoms per CG bead, the more accurate the calculated mechanical properties. Then, the pull-out models and thermal models of CNT and Gr were established. Finally, interface layer models were established. Constrained shear was applied on the copper layer, and the friction coefficient of the PTFE friction materials was obtained. The larger action strength of Gr which compared to CNT has a greater enhancement and antifriction effect on PTFE. The enhanced mechanism was explored by interaction energy, thermal and tribological analysis. This study will provide the fundamental theory for designing advanced polymer nanocomposites.

Carbon nanotube (CNT) based membranes are emerging as next-generation materials due to their exceptional transport properties and high selectivity, particularly in applications such as desalination and drug delivery. However, these membranes typically rely on a complex system of physical gradients to achieve transport, which poses significant challenges for their practical implementation. This paper introduces a potential alternative method that bypasses the need for physical gradients by simply leveraging the frictional motion of the wetted interface to drive liquid transport through CNT/polymer membranes. Molecular dynamics (MD) simulations and comparative experiments demonstrate that the driving force of this method arises from friction-induced normal vibrations and shear-induced horizontal traction, with Coulomb interactions ensuring continuous liquid flow. This research provides more options for the driving methods of CNT/polymer membrane systems and establishes a theoretical foundation for their practical application in advanced membrane technologies.

PurposeThe purpose of this paper is to investigate the effect of 3 wt.% copper oxide (CuO), zirconium dioxide (ZrO2) and silicon dioxide (SiO2) nanoparticles on the mechanical, thermal and tribological properties of polytetrafluoroethylene (PTFE) composites from an atomic level.Design/methodology/approachEffects of CuO, ZrO2 and SiO2 on the mechanical, thermal and tribological properties of PTFE were studied by molecular dynamics (MD) simulations to explore the inherent mechanisms from an atomic level. Cu/polymer/Cu sandwich models were sheared for friction function.FindingsAmong the three nanoparticles, 3 wt.% ZrO2 has the best enhancing effect on the mechanical and thermal properties of PTFE, with the Young's modulus and shear modulus increasing by 376.3% and 197.1%, respectively. And ZrO2/PTFE has the best compressive resistance. It is 61.37% higher than pure PTFE. ZrO2/PTFE has the highest glass transition temperature. It is 43 K higher than pure PTFE. Also, 3 wt.% CuO/PTFE can effectively reduce the friction coefficient of PTFE by 68.7%. The increase in glass transition temperature and mechanical properties reduces the coefficient of friction, as stronger nanoparticle adsorption weakens their interaction with the frictional interface.Originality/valueThis study reveals the mechanism of CuO, ZrO2 and SiO2 on the mechanical, thermal and tribological behavior of PTFE by MD simulation.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2025-0276/

Phenolic resin is widely used in industry due to its excellent cost performance. However, its mechanical, thermal, and tribological performance needs to be improved. In this paper, hexagonal boron nitride (h-BN)/carbon fiber/molybdenum disulfide composites modified boron phenolic resin (BPF) matrix composites were designed and prepared. A systematic investigation was conducted to examine how varying amounts of h-BN affect the composite's mechanical strength, friction behavior, and thermal performance. The reinforced mechanism was explored by molecular dynamics simulation. As the h-BN content rises, the composite exhibits enhanced hardness while its impact resistance shows a declining trend. Thermal stability and thermal conductivity are improved. The composites exhibit a downward trend followed by an upward shift in both the friction coefficient and wear rate and finally reach the lowest level when the h-BN content is 6 wt.%. By worn morphology analysis, it is found that wear rate increase is due to the h-BN enrichment, which affects the bonding properties of the composites. The outcomes of the simulation suggest that the interaction strength between the BPF matrix and h-BN becomes stronger as the h-BN content increases. Meanwhile, the mean square displacement of the system initially declines and then rises when the composite models were prepared with filler concentrations of 0, 2, 6, and 10 wt%. It provides theoretical support for the change of hardness and wear rate at the molecular level. This study provides guidance for designing high-performance BPF matrix composites.

This study employs molecular dynamics (MD) simulations with Stillinger-Weber (SW) and Embedded Atom Method (EAM) potentials to investigate the tribological behavior of WS2 coatings on a copper substrate against spherical alumina indenter. Various loads, rotational speeds, and temperatures are explored to analyze their effects on tribological properties. The investigation reveals compelling insights: load-dependent frictional behavior, elucidation of non-linear stress patterns with rotational speeds, and the discernment of temperature-induced alterations in friction coefficient. Furthermore, through detailed analysis utilizing Radial Distribution Function (RDF) methodology, molecular rearrangement dynamics are unveiled, enriching our understanding of the WS2-copper interplay. This research contributes to understanding the intricate dynamics of WS2 coatings and copper interactions, crucial for optimizing tribological performance in practical applications.

A profound comprehension of friction and wear mechanisms is essential for the design and development of high-performance polymeric materials for tribological application. However, it is difficult to deeply investigate the polymer friction process in situ at the micro/mesoscopic scale by traditional research methods. In recent years, molecular dynamics (MD) simulation, as an emerging research method, has attracted more and more attention in the field of polymer tribology due to its ability to show the physicochemical evolution between the contact interfaces at the atomic scale. Herein, we review the applications of MD in recent studies of polymer tribology and their research focuses (e.g., tribological properties, distribution and conformation of polymer chains, interfacial interaction, frictional heat, and tribochemical reactions) across three perspectives: all-atom MD, reactive MD, and coarse-grained MD. Additionally, we summarize the current challenges encountered by MD simulation in polymer tribology research and present recommendations accordingly, aiming to provide several insights for researchers in related fields.

This study investigates the impact of zinc oxide nanoparticles on epoxy resin systems and the ultraviolet (UV) aging resistance of modified epoxy resin composites using molecular dynamics (MD) simulations and experimental methods. Initially, various epoxy resin cross-linking models are established through MD simulations to understand the influence of different nano ZnO contents on resin modification, further validated by experiments. Subsequently, the UV radiation resistance of nano ZnO-epoxy resin composites is assessed by subjecting them to high-intensity UV radiation equivalent to 3 years of natural environmental conditions, analyzing changes in tensile properties, impact performance, hardness, and glass transition temperature of epoxy resin before and after UV radiation exposure. The findings suggest that the addition of nano zinc oxide reduces the impact of UV radiation on epoxy resin, with optimal UV radiation resistance observed at a nano zinc oxide mass fraction of 0.3 wt%.

This study aims to investigate the shear behavior of epoxy resin adhesives at different temperatures, and to reveal the shear mechanism through experimental tests and molecular dynamics(MD) simulations. The shear strength at different temperatures was experimentally tested. With the increase of temperature, the shear strength decreases obviously. Then, the three-layer shear model was constructed based on the experimental process, and shear simulations were conducted at the corresponding temperatures. The simulations reveal that with increasing temperature, the adhesive exhibit more intense thermal motion, leading to a decrease in cohesive energy density. Additionally, as the temperature rises, the energy of the system increases, rendering it more unstable and resulting in a decrease in shear strength. This study provides valuable insights into the temperature effects on the shear process of epoxy resin adhesives.

In this study, three kinds of micro-arc oxidation (MAO) coatings based on the 2A12 aluminum alloy were prepared with molybdenum disulfide (MoS2), tungsten disulfide (WS2), and graphene oxide (GO) in hexametaphosphate composite electrolyte to improve the tribological performance, respectively. Voltage–time responses were recorded. The microstructure, composition, and element distribution were analyzed by x-ray diffractometer (XRD), SEM, and energy-dispersive x-ray spectroscopy (EDS). The ball-on-disk friction tests were performed to investigate the tribological properties. The wear tracks were observed by SEM. XRD and EDS results indicated that during the MAO treatment process, all three types of particles were effectively incorporated into the oxide coating, with GO displaying a more active participation in the film-forming process due to its solubility in water. The addition of solid lubricants increased the hardness of the coatings and reduced surface roughness, with graphene oxide (GO) being the most effective, achieving the lowest friction coefficient at 0.32. Further investigation into coating Al2O3/GO revealed the heat generated during friction process caused the oxidation of iron elements from the counterpart, which then adhered to the wear scar. GO altered the wear mode between the coating and the counterpart, transitioning from abrasive wear to adhesive wear.