Interfacial Adhesion Force Research Articles

Self-cleaning and corrosion-resistant superamphiphobic coating with super-repellency towards low-surface-tension liquids

In this paper, we designed and fabricated a liquid-repellent coating that features both superhydrophobicity and superoleophobicity, viz. Superamphiphobic properties, based on dual adhesive tape binding layer and 1H,1H,2H,2H-perfluorodecyltriethoxysilane modified aluminum oxide nanoparticles (Al2O3@PDFTES NPs). The constructed superamphiphobic coating presented non-wetting, high contact angles (CA), and low sliding angles (SA) towards various liquids with different surface tensions including water (CA = 167.6 ± 3.5°, SA = 2.9 ± 0.6°), glycerol (CA = 154.2 ± 2.7°, SA = 4.7 ± 0.4°), ethylene glycol (CA = 156.1 ± 2.4°, SA = 5.8 ± 0.2°), and peanut oil (CA = 155.2 ± 2.8°, SA = 6.5 ± 0.7°). The dynamic self-cleaning behaviors driven by water-, oil-, and hot water droplets verified the super-repellency, ultra-low surface energy, and interfacial adhesion force. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements showed >250 mV positive shifting of Ecorr, 4 orders of magnitude lower Icorr, 7 orders of magnitude higher Rct and |Z| modulus values, demonstrating a significantly improved corrosion resistance of the superamphiphobic coating. The synergistic effect of the Al2O3@PDFTES NPs with low surface energy and the adhesive tape layer with interfacial binding force contribute to the development of stably self-cleaning and anti-corrosion superamphiphobic coating, which will be a potential candidate for protective interfacial materials for marine and industrial applications.

Interfacial Adhesion Forces of Hydrate Particles in the Presence of Hydrate Inhibitors

Hydrate inhibitors are traditionally utilized to prevent hydrate plugging. In this study, the adhesion forces of cyclopentane (CP) hydrates with thermodynamic inhibitors (ethanol, urea, and NaCl) and anti-agglomerant inhibitors [sorbitan monooleate (Span 80) and lecithin] were measured to understand the effects of hydrate inhibitors on the adhesion forces of hydrates. It was found that the thermodynamic inhibitors increased the early hydrate interparticle adhesion force due to the enhanced liquid bridge force. However, the liquid bridge acted as a lubricant layer to prevent the irreversible agglomeration of hydrate after long-term contact. The hydrate adhesion forces decreased by 90.5-93.0% and 76.6-92.7% with an increase in the concentration of Span 80 and lecithin, respectively, from 0.1 to 1 wt %. Both rough morphology and low interfacial tension contributed to the adhesion force decrease of hydrate after the addition of anti-agglomerant inhibitors. The results may be helpful for understanding the mechanism of influence and quantifying the impact of hydrate inhibitors on hydrate interparticle adhesion force.

Measurement of Interfacial Adhesion Force with a 3D-Printed Fiber-Tip Microforce Sensor.

With the current trend of device miniaturization, the measurement and control of interfacial adhesion forces are increasingly important in fields such as biomechanics and cell biology. However, conventional fiber optic force sensors with high Young’s modulus (>70 GPa) are usually unable to measure adhesion forces on the micro- or nano-Newton level on the surface of micro/nanoscale structures. Here, we demonstrate a method for interfacial adhesion force measurement in micro/nanoscale structures using a fiber-tip microforce sensor (FTMS). The FTMS, with microforce sensitivity of 1.05 nm/μN and force resolution of up to 19 nN, is fabricated using femtosecond laser two-photon polymerization nanolithography to program a clamped-beam probe on the end face of a single-mode fiber. As a typical verification test, the micronewton-level contact and noncontact adhesion forces on the surfaces of hydrogels were measured by FTMS. In addition, the noncontact adhesion of human hair was successfully measured with the sensor.

Rollable Ultraviolet Photodetector Based on ZnAl‐Layered Double Hydroxide/Polyvinylidene Fluoride Membrane

AbstractHigh‐performance, reliable, and rollable ultraviolet (UV) photodetectors have attracted considerable attention for wireless sensor network technology. Despite the improved responsivity of UV photodetectors, high‐performance rollable UV photodetectors have not been reported. This paper reports a rollable UV photodetector based on ZnAl‐layered double hydroxide (LDH) nanosheets on a porous polyvinylidene fluoride (PVDF) membrane. Vertically aligned ZnAl‐LDH nanosheets are grown on a porosity‐controlled PVDF membrane. The UV photodetector exhibits an excellent photoresponse at wavelengths below 420 nm, even in curvature with a 0.6 mm radius. The rollable UV photodetector also shows reliable, responsive performance even after 5 000 rolling cycles, indicating the reasonable durability of the ZnAl‐LDH nanosheet. The reliable photodetector performance is attributed to the elasticity of the PVDF and the strong interfacial adhesion force between the porous PVDF and ZnAl‐LDH nanosheets.

The interfacial adhesion of contacting pairs in van der Waals materials

The interfacial adhesion of contacting pairs between two adjacent layers of 2D van der Waals (vdW) layered materials and between 2D materials and their supporting substrates are essential for manipulating 2D materials and constructing functional 2D materials incorporated devices. Here, the interfacial adhesion forces and energies of various contacting pairs involving 2D materials and their underlying physical mechanisms are investigated by combining atomic force microscopy (AFM) measurements and density functional theory (DFT) calculations. The distinct adhesion forces are verified by selecting various contacting pairs between a bare or graphene-coated Si tip and tungsten disulfide (WS2) or graphene as the 2D materials. When using the bare Si tip, the adhesion forces between tip and monolayer WS2 or bilayer WS2 are determined as 32.07 nN or 38.20 nN, respectively. The adhesion forces between the graphene-coated Si tip and monolayer WS2 or graphene are 14.80 nN or 12.28 nN, respectively. Furthermore, the in-depth density functional theory (DFT) calculation results indicate that a distinctly different charge transfer contributes to the different magnitude of the adhesion forces. Our findings demonstrate that the interfacial interaction is an intrinsic property and critically dependent on the type of 2D materials, suggesting a potential strategy for distinguishing 2D materials by adhesion forces.

Adhesion is safe to the refractive surgeries: A theoretical analysis

Adhesion behavior, existed on the damaged interface, was responsible for the safety and stability of the post-operative cornea refer to the refractive surgeries. In this study, we inferred that the force loss generated by the post-operative cornea must do not surpass the interfacial adhesion force of the cornea. In case of that, the corneal flap (or cap) would trend to separate from the residual stromal bed, and then became a threat to the visual health of the corrected myopic patient. According to this inference, we derived the theoretical maximum ablated ratio, which was well matched with the empirically clinical safety standard employing the commonly programmed optical zone.

Interfacial architecting of organic–inorganic hybrid toward mechanically reinforced, fire-resistant and smoke-suppressed polyurethane composites

Polyurethane (PU) composites integrated with outstanding fire retardancy, smoke suppression as well as ameliorated mechanical property is attractive, but remains a challenge. Here, we demonstrate the interfacial architecting of organic–inorganic hybrid (ACAPP) by reacting renewable chitooligosaccharide (COS) with ammonium polyphosphate (APP) and ammonium octamolybdate (AOM) via a one-pot, facile and eco-friendly approach. The ACAPP with multiple hydroxyl groups shows good compatibility and strong interfacial adhesion force with PU matrix due to the abundant covalent cross-linking points and hydrogen bonds networks. The incorporation of 15 wt% ACAPP enables the resultant PU composite to achieve a V-0 rating, a limiting oxygen index of 26.1%, 31.1% and 44.8% reduction in total heat release and total smoke production, respectively, far outdistancing conventional APP. The suppressed fire hazards mainly benefits from the synergy catalytic carbonization effect of ACAPP in condensed phase. Moreover, ACAPP reinforces the tensile strength of PU whilst retaining the decent ultimate elongation. This work may offer a referable exemplification for constructing green flame-retardant to balance high fire safety and mechanical properties.

Modulation of Interfacial Adhesion Using Semicrystalline Shape-Memory Polymers.

Semicrystalline shape-memory elastomers are molded into deformable geometrical features to control adhesive interactions between elastomers and a glass substrate. By mechanically and thermally controlling the deformation and phase-behavior of molded features, we can control the interfacial contact area and the interfacial adhesive force. Results indicate that elastic energy is stored in the semicrystalline state of deformed features and can be released to break attractive interfacial forces, automatically separating the glass substrate from the elastomer. Our findings suggest that the shape-memory elastomers can be applied in various contact printing applications to control adhesive forces and delamination mechanics during ink pickup and transfer.

Self-reinforced composites based on polypropylene fiber and graphene nano-platelets/polypropylene film

Self-reinforced polymer composites (SrPCs) have many advantages such as light weight, easy recyclability, improved bonding, and low cost. However, the enhancement of mechanical properties of SrPCs is generally restricted by the composite structure and the narrow processing temperature window. The combination of graphene and self-reinforcing mechanism is a potential method to realize a significant improvement in the mechanical properties of polymer composites. It is necessary to study the self-reinforcing mechanism on adjusting the orientation of graphene, so as to reduce the amount of graphene and improve the mechanical properties. This paper presents SrPCs that combine polypropylene (PP) fibers and graphene nano-platelets (GnPs)/PP composite films through film stacking. The unidirectionally arranged PP fibers form narrow channels which facilitate the orientation of GnPs during the impregnation process. The prepared GnPs/PP SrPCs were characterized in comparison with neat PP. At a very low GnPs content of only 0.019 wt%, the tensile strength and modulus of PP were increased by 152% and 186%, respectively, and the interfacial adhesion force of PP SrPCs was improved by 280%. Numerical simulation was successfully conducted to evaluate the processing temperature and the mechanism of graphene orientation in the film stacking process. It proved that the GnPs were highly oriented over the region of unidirectional fibers by the flow field. This new technical method can be potentially used in the industrial manufacturing of economical graphene/polymer nanocomposites with superior mechanical properties.

The Development of Fine Surface Roughness of FeCrAl Substrate by Gamma Alumina Coating Material Through Nickel Oxide Catalyst

The most commonly used method for protecting atmospherically exposed steel against corrosion, is the application of protective organic coating systems. It is widely recognized that the stability of the coating-substrate interface is related to the interfacial adhesion forces and electrochemical properties of this region. This study aim to develop fine surface roughness by ultrasonic and electroplating coating methods that applied for FeCrAl catalytic converter. This method consists of thwo methods which are ultrasonic bath that carried out by frequency of 35 kHz and various ultrasonic times of 1, 1.5, 2, 2.5 and 3 hours is imposed and the electroplating was conducted for several variation times of 15, 30, 45, 60 and 75 minutes, current density of 8 A/dm2. The result shows that the surface roughness of UB samples in between 0.11 to 0.21 µm, UBdEL samples of 0.81 to 2.17 µm, UB+EL samples of 0.64 to 1.63 µm and EL samples of 0.69 to 1.11 µm. The finest surface of each techniques are located at UB 1.5 h, UBdEL 45 minutes, UB 1.5 h+EL 30 minutes and UB 30 minutes. That data is supported by coating thickness of coated FeCrAl substrate where UB samples in between 2 -2.8 µm, UBdEL samples of 4.1 to 5 µm, UB+EL samples of 9.1 to 12 µm and EL samples of 6.2 to 11.3 µm.

A facile mold-free micromechanical method for patterning multilayer graphene by utilizing the difference in interfacial adhesion forces

We report a method to pattern graphene on silicon dioxide by a physical process utilizing its inter-facial properties with metal, silicon dioxide and polymer photoresist. The process utilizes the difference in adhesion energies of various interfaces between these materials with graphene. The mechanical forces involved in this process are strong enough to pattern multiple layers of graphene at once. As the sacrificial patterning layer is in flush contact with graphene, the process does not suffer from residual layers at the undesired sites, as in polymer-based stamp transfer techniques. We have calculated the adhesion energies of these interfaces using density functional theory (DFT), theoretical estimation and experimental methods using Atomic Force Microscopy (AFM). These observations are in good agreement with each other and defend the feasibility of the proposed graphene patterning method.

Predicting interfacial layer adhesion strength in 3D printable silicone

Direct ink writing is an excellent method for depositing soft elastomeric silicones into a 3D shape, as shown by several examples in the current literature. However, further investigation into the quality of these 3D printed parts is required to ensure this process can be reliable. Especially for fields like soft robotics, where these printed silicone parts are inflated and the bulk material is in tension, interfacial layer adhesion is integral to the ultimate tensile robustness of a part and preventing premature failure. Interfacial layer adhesion changes based on the cure state of the previously deposited silicone layer, which can change based on amount of cure retarding additives, when the material was last mixed, and the temperature of the printing chamber. Yet, interfacial layer adhesion between printable silicone has not yet been characterized in the literature. This work seeks to rectify that by quantifying the relationship between curing kinetics, tested using differential scanning calorimetry, and peel testing of a printable Ecoflex 00-30 based silicone formulation. These data show a negative correlation between cure percent and interfacial adhesion force with values usable for prediction of printed part tensile strength. These data are then implemented into a G-code visualization tool to display the interfacial adhesion quality based on CAD model geometry and print speed. This work shows that cure percent has to be incorporated into direct ink write path planning to ensure control of the part’s final tensile behavior. • Interfacial peel strength decreases with increasing cure percent between DIW curing silicone layers. • Data in the literature is currently missing for interfacial layer adhesion strength in silicone DIW. • Peel strength should be incorporated into DIW path planning to ensure predictable material properties.

Recycle of ceramic substrate of PDMS/ceramic composite membranes towards alcohol-permselective pervaporation

Nowadays, membrane recycling has received increasing attention in water treatment, gas separation and pervaporation. Compared with polymeric substrates, inorganic substrates possess higher mechanical and thermal stability, which can be reused to balance the high cost. In this work, for the first time, we studied the recycle of inorganic substrate that was used for fabricating polymeric composite membranes. A facile approach was proposed to recycle ceramic substrate from PDMS/ceramic composite membranes with thermal degradation followed by ultrasonic cleaning. The thermal degradation compositions of PDMS membrane under air or nitrogen atmosphere were investigated by using TGA-IR, XRD and XPS analysis. Influence factors of the recycle approach including degradation conditions, cleaning approach and multi-recycle process were explored to optimize the transport properties of ceramic substrate and PDMS/ceramic composite membrane. The interfacial morphologies and adhesion of the PDMS membrane coated on the recycled ceramic substrate were characterized by SEM and nano-scratch measurement. The results demonstrated that PDMS composite membrane fabricated on the ceramic substrate with 10 times recycle by thermal degradation in nitrogen at 800 °C for 4 h and ultrasonic cleaning could still achieve >92% separation performance and interfacial adhesive force of the fresh PDMS/ceramic composite membrane. Specifically, the membrane exhibited stable flux of 1.2 kg/m2h and separation factor of 8.1 for 120 h continuous pervaporation separation of 5 wt% ethanol/water at 40 °C. Additionally, ∼75% energy saving relative to synthesizing fresh ceramic substrate was estimated for applying the feasible recycle approach.

INFLUENCE AND REGULATION OF INTERFACIAL ADHESION PROPERTIES OF A MAGNETIC SENSITIVE FILM/SUBSTRATE BY MAGNETIC FORCE AND FILM'S CURVATURE

The controllable interface adhesion of attachment and detachment has important application requirements in climbing devices, adhesion switches and mechanical grippers. In present paper, the influence mechanism of external magnetic field and film's initial curvature on the interfacial adhesion of a magnetic sensitive film/substrate is studied. The peel-test of the magnetic sensitive thin film with initial curvature on a substrate as well as the corresponding theoretical study are respectively carried out. Both the experimental and theoretical results indicate that the interfacial adhesion force of the magnetic sensitive thin film/substrate increases with increasing the initial curvature of the film, and the external magnetic field can enhance the interfacial adhesion force. Compared with the steady-state peel-off force of a flat thin film that is independent on the bending stiffness, the bending stiffness would decrease the steady-state peel-off force of the film with initial curvature. The interface effective adhesion energy is further considered from the energy point of view, which can disclose the comparing mechanisms of the film's bending energy, the potential energy of external magnetic field and the adhesion energy. Lastly, based on the experimental and theoretical results, a simply mechanical gripper controlled by both the magnetic field and film's initial curvature is proposed, which can continuously realize the gripping, transport and release of an object. The results obtained in the present paper can not only be helpful for understanding the interface reversible adhesion mechanism actuated by multi-field, but also provide a novel approach to design functional devices with controllable interface adhesion.

Thermal radiation shielded, high strength, fire resistant fiber/nanorod/aerogel composites fabricated by in-situ growth of TiO2 nanorods for thermal insulation

• Vertically aligned TiO 2 nanorods were synthesized directly on the surface of microfibers by in-situ growth. • A novel ‘fiber/nanorod/aerogel’ composite was constructed for thermal insulators. • The composite with low thermal conductivity exhibited significantly enhanced infrared radiation shielding. • In-situ growth of TiO 2 nanorods reduced the gaseous conductivity by increasing the interfacial adhesion force. Fiber/aerogel composites attract considerable interest as thermal insulation materials due to their low thermal conductivity. However, in practice they deliver unsatisfactory performance due to their high infrared radiation transmittance and poor interfacial adhesion. Herein, we report a simple strategy for constructing vertically aligned 1D rutile TiO 2 nanorod arrays (TiO 2 -NRAs) directly on the surface of quartz fibers (QFs) by in-situ growth. A novel ‘fiber/nanorod/aerogel’ composite was synthesized by filling the pores of QF/TiO 2 -NRAs with SiO 2 -Al 2 O 3 aerogels (ASAs) through vacuum impregnation. The QF/TiO 2 -NRAs/ASA composite exhibited excellent thermal insulation (0.071 W·m −1 ·K −1 at 1100 °C), infrared radiation shielding performance (an extinction coefficient greater than 150 cm −1 and an infrared reflectivity greater than 95%), fire resistance (more than 1200 °C), and compressive strength (0.37 MPa, 10% strain). In-situ growth of TiO 2 -NRAs can reduce the gaseous thermal conductivity by increasing the interfacial adhesion force between fibers and aerogels, and reduce the radiation heat transfer by shielding infrared radiation. This strategy is applicable to multi-type fibers reinforced silica-based aerogel materials used for insulation and protection in extreme environments.

Real-time manipulation fluid-solid interfacial friction and adhesion force by electrowetting on dielectric

Fluid-solid interfacial friction and adhesion behaviors play critical roles in microfluidic control systems. In this paper, the responses of fluid-solid interfacial friction force and adhesion force to voltage were studied under electrowetting conditions. Results showed that the fluid-solid interfacial friction force increased two orders of magnitude by voltage in the electrowetting transition region. The responses of friction force and adhesion force to the voltage were almost instantaneous on the time scale. It is indicated that the friction force and adhesion force can be manipulated over a wide range in real-time by voltage. The findings are helpful to provide a method for manipulating the fluid-solid interfacial friction force and adhesion force in real-time using voltage.

Mechanical Properties of the Interfacial Bond between Asphalt-Binder and Aggregates under Different Aging Conditions.

Aging has a detrimental impact on the interfacial interaction and bonding between asphalt-binder and aggregates, which influence ultimately on the performance of asphalt mixtures and pavements. Evaluation of the mechanical properties of the interface between the asphalt-binder and aggregates has thus become a hot research topic, particularly as a function of aging. In this study, the interfacial tensile strength, compressive strength, elastic modulus, and interfacial recovery energy were measured and quantified using molecular dynamic simulation. Whilst the free volume of the asphalt mixtures exhibited sensitivity to aging, the interfacial tensile strength decreased with an increase in the degree of aging. In general, the mechanical properties of the asphalt-binder-aggregate interface were found to be significantly dependent on the aggregate type. Furthermore, the study results indicated that interfacial recovery energy is a key characteristic property for characterizing the interfacial adhesive force within asphalt mixtures. Overall, the study of mechanical properties of the asphalt-binder and aggregate interface, as presented in this paper, contributes to quantifying the adhesive properties and improving the performance of asphalt mixtures.

A theoretical study on three long-range interactions between two nanoparticles under the humid condition

At the micro/nanoscale under the humid condition, the competition among three long-range interactions of the electrostatic, cohesive, and capillary forces dominates the adhesive behavior between two nanoparticles. In this study, explicit solutions of the interfacial adhesive energy between two nanoparticles are obtained through continuum modeling by considering the three long-range interactions between them, where the Coulomb theorem, the Lennard–Jones potential, and the Young–Laplace equation are taken into consideration. The present theoretical results show that the interfacial adhesive forces strongly depend on the three interactions, where the cohesive force and capillary force play more important roles in the competition for a smaller distance h between two nanoparticles, while the electrostatic force dominates the interactions for a larger distance h. Checking against present molecular dynamics simulations shows that the present continuum solution has high accuracy. This study should be of great help for deeply understanding the aggregation and separation of nanoparticles under the humid condition.

Bio-inspired Superhydrophobic Coating with Low Hydrate Adhesion for Hydrate Mitigation

In this paper, we fabricate a biomimetic superhydrophobic coating on an X90 pipeline steel substrate by electrodeposition of copper, hydrothermal treatment to form a copper oxide layer, and subsequent surface modification with Stearic Acid (SA). The coating exhibits static contact angles of water of 160° ± 3.1° in the air and 170.7° ± 2.5° in cyclopentane, indicating the strongly water-repelling nature of the coating. The morphologies of the cyclopentane hydrate formed on steel substrates with and without the superhydrophobic coating are investigated. The results show that the hydrate particle on the coating exhibits spherical morphology and herein the interfacial contact area and adhesion force to the solid surface can be essentially reduced. The adhesion force reduction may be resulted by the decrease in the contact area between the hydrate and the solid surface.

Rational design of robust nano-Si/graphite nanocomposites anodes with strong interfacial adhesion for high-performance lithium-ion batteries

The nano-Si/graphite nanocomposites are the promising anodes candidates for high-energy lithium-ion batteries because of their high theoretical capacities and low volume variations. However, the nano-Si has a severe tendency to separate from the graphite substrate due to the inherently weak bonding between them, thus leading to the deteriorated cycling performance and low Coulombic efficiency. Herein, we design a robust nano-Si/graphite nanocomposite structure with strong interfacial adhesion caused by the SiTi and TiC covalent bonds. The abundant SiTi and TiC bonds formed between nano-Si and graphite greatly enhance the interfacial adhesion force, resulting in the highly stabilized and integrated electrode structure during battery cycling. Consequently, the as-obtained nano-Si/graphite anodes deliver a high capacity retention of 90.0% after 420 cycles at 0.5 C with an average Coulombic efficiency of 99.5%; moreover, a high initial Coulombic efficiency of 90.2% is achieved. Significantly, this work provides a novel strategy to address the poor interfacial adhesion between nano-Si and graphite, which can be applied to other nano-Si based composites anodes.