Strategy To Enhance Interfacial Properties: Preparation of Porous Polytetrafluoroethylene Fibers and the Adsorption of Initiators/Curing Agents.

Polytetrafluoroethylene (PTFE) fibers exhibit high inertness and demonstrate limited interfacial bonding capabilities with other materials. To overcome this limitation, PTFE@ZnO fibers were developed by depositing the porous ZnO layer onto PTFE fibers via a hydrothermal reaction, and porous fibers were adsorbed curing agents or initiators. The interfacial shear strength (ILSS) of the composites demonstrated a significant improvement, particularly in the case of composites containing PTFE/initiator fibers, where the ILSS increased by 104.

Topological Rearrangement-Induced Mesoscale Phase Redistribution to Enhance the Fatigue Resistance of Polymer Blends.

Maintaining a high modulus to simultaneously withstand deformation and increase fatigue resistance to restrict crack propagation in a material presents a significant challenge. In this work, a straightforward strategy was developed to address this issue in polymers. A dynamic network was incorporated into a permanent one prior to the formation of the latter, and two incompatible polymer networks were created to prevent common phase separation.

Effects of the Mesoporous Filler and Oleophilic Property on the Tribological Behavior of Polyetheretherketone Composites.

Porous composites, such as polyimide and polyetheretherketone (PEEK) polymer composites, became more attractive as a result of excellent specific strength, lightweightness, and smart lubrication. However, revealing the influence of a porous filler on the friction behaviors of polymer composites remains a challenge. The current work examines the effects of the pore structure and wettability on the mechanical and tribological performances of polymer composites reinforced with fillers.

Self-Reinforced Piezoelectric Response of an Electroluminescent Film for the Dual-Channel Signal Monitoring of Damaged Areas.

Organic piezoelectric nanogenerators (PENGs) show promise for monitoring damage in mechanical equipment. However, weak interfacial bonding between the reinforcing phase and the fluorinated material limits the feedback signal from the damaged area. In this study, we developed a PENG film capable of real-time identification of the damage location and extent.

Self-Adaptive Macroscale Superlubricity Based on the Tribocatalytic Properties of Partially Oxidized Black Phosphorus.

The high-flash heat generated by direct contact at asperity tips under high contact stress and shear significantly promotes the tribocatalytic reaction between a lubricating medium and a friction interface. Macroscale superlubricity can be achieved by using additives with good lubrication properties to promote the decomposition and transformation of a lubricating medium to form an ultralow shear interface during the friction process. This paper proposed a way to achieve self-adaptive oil-based macroscale superlubricity on different tribopairs, including steel-steel and steel-DLC (diamond-like carbon), which is based on the excellent lubricating performance of black phosphorus with active oxidation and the catalytic cleavage behavior of oil molecules on the surface of oBP.

Partially Oxidized Violet Phosphorus as an Excellent Lubricant Additive for Tribological Applications.

As a novel two-dimensional material, violet phosphorus (VP) has attracted a considerable amount of attention due to its high carrier mobility, anisotropy, wide band gap, stability, and easy stripping properties. In this work, the microtribological properties of partially oxidized VP (oVP) and the mechanism of reducing friction and wear as additives in oleic acid (OA) oil were studied systematically. When adding oVP to OA, the coefficient of friction (COF) decreased from 0.

Tribological and Antibacterial Properties of Polyetheretherketone Composites with Black Phosphorus Nanosheets.

Over the past few decades, polyetheretherketone (PEEK) artificial bone joint materials faced problems of poor wear resistance and easy infection, which are not suitable for the growing demand of bone joints. The tribological behavior and wear mechanism of polyetheretherketone (PEEK)/polytetrafluoroethylene (PTFE) with black phosphorus (BP) nanosheets have been investigated under dry sliding friction. Compared with pure PEEK, the COF of PEEK/10 wt% PTFE/0.

Load-dependent energy dissipation induced by the tip-membrane friction on suspended 2D materials.

The tip-membrane interface plays a critical role in characterizing the mechanical properties of ultrathin 2D materials by commonly employed nanoindentation based on atomic force microscopy (AFM). However, the reliability of the assumption that the tip-membrane interface remains pinned during nanoindentation remains unclear, which may introduce unignorable uncertainty in evaluating their true mechanical properties. In this work, it is reported that load-dependent frictional behavior would occur on the tip-membrane interface during nanoindentation tests on monolayer and multilayer suspended WS and graphene, and the curve hysteresis could be well explained by the stick-slip behavior.

Reduced Fracture Strength of 2D Materials Induced by Interlayer Friction.

The potential applications of 2D layered materials (2DLMs) as the functional membranes in flexible electronics and nano-electromechanical systems emphasize the role of the mechanical properties of these materials. Interlayer interactions play critical roles in affecting the mechanical properties of 2DLMs, and nevertheless the understanding of their relationship remains incomplete. In the present work, it is reported that the fracture strength of few-layer (FL) WS can be weakened by the interlayer friction among individual layers with the assistance of finite element simulations and density functional theory (DFT) calculations.

Synthesis of Core-Shell Micro/Nanoparticles and Their Tribological Application: A Review.

Owing to the diverse composition, adjustable performance, and synergistic effect among components, core-shell micro/nanoparticles have been widely applied in the field of tribology in recent years. The strong combination with the matrix and the good dispersion of reinforcing fillers in the composites could be achieved through the design of core-shell structural particles based on the reinforcing fillers. In addition, the performance of chemical mechanical polishing could be improved by optimizing the shell material coated on the abrasive surface.

Thickness-dependent Young's modulus of polycrystalline α-PbO nanosheets.

Litharge, in two dimensional (2D) nanostructure form, has recently ignited considerable theoretical interest due to its excellent photoelectric and magnetic properties. However, the lack of an efficient synthesis method hinders its development. Here, we provide an interfacial solvothermal strategy for controllably synthesizing ultrathin hexagonal polycrystalline α-PbO nanosheets in micrometer scale.

Super-Slippery Degraded Black Phosphorus/Silicon Dioxide Interface.

The interfaces between two-dimensional (2D) materials and the silicon dioxide (SiO)/silicon (Si) substrate, generally considered as a solid-solid mechanical contact, have been especially emphasized for the structure design and the property optimization in microsystems and nanoengineering. The basic understanding of the interfacial structure and dynamics for 2D material-based systems still remains one of the inevitable challenges ahead. Here, an interfacial mobile water layer is indicated to insert into the interface of the degraded black phosphorus (BP) flake and the SiO/Si substrate owing to the induced hydroxyl groups during the ambient degradation.

In-Plane Potential Gradient Induces Low Frictional Energy Dissipation during the Stick-Slip Sliding on the Surfaces of 2D Materials.

Understanding the nanoscale friction properties of 2D materials and further manipulating their friction behaviors is of great significance for the development of various micro/nanodevices. Recent studies, taking advantage of the close relationship between friction and surface charges, use an external out-of-plane electric field to control the interfacial friction. Nevertheless, friction increases with the application of the out-of-plane electric field in most cases.

Two-dimensional layered materials: from mechanical and coupling properties towards applications in electronics.

With the increasing interest in nanodevices based on two-dimensional layered materials (2DLMs) after the birth of graphene, the mechanical and coupling properties of these materials, which play an important role in determining the performance and life of nanodevices, have drawn increasingly more attention. In this review, both experimental and simulation methods investigating the mechanical properties and behaviour of 2DLMs have been summarized, which is followed by the discussion of their elastic properties and failure mechanisms. For further understanding and tuning of their mechanical properties and behaviour, the influence factors on the mechanical properties and behaviour have been taken into consideration.

Core-shell nanospheres to achieve ultralow friction polymer nanocomposites with superior mechanical properties.

Core-shell nanospheres have been widely used in catalysis, batteries, medicine, etc. owing to their unique structural characteristics, which exhibit optimal performance and integrated functions of both the core and shell materials. To simultaneously achieve outstanding mechanical properties and remarkable lubrication properties in desirable polymer composites, core-shell nanospheres with polytetrafluoroethylene (PTFE) as the core and poly methyl methacrylate (PMMA) as the shell have been adopted as structural units to form bulk nanocomposites.

Superlubricity of Black Phosphorus as Lubricant Additive.

Superlubricity is defined as a sliding regime in which friction, or the resistance to sliding of two relatively moving surfaces, almost vanishes. From a practical point of view, the development and use of new materials that can enable superlubricity (coefficient of friction, COF < 0.01) in moving mechanical systems will have huge positive impact on energy-saving and emission reduction.

Electromechanical failure of MoS nanosheets.

Molybdenum disulfide (MoS2) has attracted particular attention as a promising electronics and optoelectronics material due to its significant physical properties. In this research, the electromechanical properties of MoS2 nanosheets are systematically investigated with the conductive AFM nanoindentation method. The suspended MoS2 nanosheets with the thickness of tens of nanometers can sustain external applied load (∼4.

Nanotribological Properties of Graphite Intercalation Compounds: AFM Studies.

Tetraalkylammonium salts have larger ions than metal ions, which can greatly change the interlayer space and energy, and then potentially tune the properties of graphite. In this work, various graphite intercalation compounds (GICs) have been synthesized by intercalating tetraoctylammonium bromide (TOAB) ions into graphite through electrochemical interactions under different reduction potentials. Different degrees of expansion between graphite layers as well as their corresponding structures and topographies have been characterized by different analytical techniques.

Softened Mechanical Properties of Graphene Induced by Electric Field.

The understanding on the mechanical properties of graphene under the applications of physical fields is highly relevant to the reliability and lifetime of graphene-based nanodevices. In this work, we demonstrate that the application of electric field could soften the mechanical properties of graphene dramatically on the basis of the conductive AFM nanoindentation method. It has been found that the Young's modulus and fracture strength of graphene nanosheets suspended on the holes almost stay the same initially and then exhibit a sharp drop when the normalized electric field strength increases to be 0.

Silica-Coated Core-Shell Structured Polystyrene Nanospheres and Their Size-Dependent Mechanical Properties.

The core-shell structured PS/SiO composite nanospheres were synthesized on the basis of a modified Stöber method. The mechanical properties of monodisperse nanospheres were characterized with nanoindentation on the basis of the atomic force microscopy (AFM). The surface morphologies of PS/SiO composite nanospheres was scanned with the tapping mode of AFM, and the force-distance curves were measured with the contact mode of AFM.

Low-Temperature Associated Interface Influence on the Black Phosphorus Nanoflakes.

The temperature-dependent structure properties of few-layer black phosphorus (BP) nanoflakes supported on the Si substrate and suspended on the holes are investigated using the Raman spectroscopy in the range of 77-293 K. The temperature coefficients of three main Raman modes for supported BP are larger than those of suspended BP because of the interface effects, mainly the tensile strain and the different thermal expansion coefficients (TEC) between the substrate and BP nanoflakes. The out-of-plane vibration is more apt to be affected by the initial strain, whereas the influence on the in-plane vibrations is negligible.

Tunable Adsorption and Film Formation of Mussel Adhesive Protein by Potential Control.

Mussel adhesive proteins are of great interest in many applications because of their outstanding adhesive property and film-forming ability. Understanding and controlling the film formation and its performance is crucial for the effective use of such proteins. In this study, we focus on the potential controlled film formation and compaction of one mussel adhesive protein, Mefp-1.