Liquid Adhesion Research Articles

Decoupling the mechanical role of pore liquids in soils to liquid viscous effect and solid–liquid adhesion effect

Decoupling the mechanical role of pore liquids in soils to liquid viscous effect and solid–liquid adhesion effect

A Facile Liquid Alloy Wetting Enhancing Strategy on Super‐Hydrophobic Lotus Leaves for Plant‐Hybrid System Implementation

AbstractPlant‐hybrid systems have demonstrated exciting opportunities in plant health sensing, climate monitoring, and energy harvesting, endowing great prospects for connecting plants to man‐made digitalized world. Due to its intrinsic softness/stretchability, biocompatibility, and non‐invasion, liquid alloy has shown great advantages in plant‐hybrid system implementation. However, many widely seen plant organisms having micro‐nano surface structures and waxy layer, e.g., lotus leaves, showing super‐hydrophobic behavior, prevent the liquid alloy adhesion and further its implementation of plant‐hybrid systems. By introducing a low‐concentration soap solution as an intermediate layer onto super‐hydrophobic leaves, the authors thereby propose a facile liquid alloy wetting enhancing strategy and well print liquid alloy circuits on the leaves to form plant‐hybrid systems. Surfactants (in the soap) enhance the wetting ability of solution on the lotus leaf surface, and subsequently the attracted water on the leaf surface contributes to make liquid alloy adhered on super‐hydrophobic leaves. Furthermore, the authors demonstrate the liquid alloy plant‐hybrid implementation based on the lotus leaves for the perception of human body, and set a system as a home intrusion alarm. This work presents an excellent example of digitalized integration on super‐hydrophobic plant organisms, which provides a new tool technology for plant‐hybrid implementations and broadens the digitalized application range of plants.

Study on Influence of Adhesion Properties in Screen Printing Electronic Ink Transfer

Printing electronic components by screen printing with the excellent printing quality, high efficiency, and environmental protection has broad application prospects in additive manufacturing. However, because conductive-ink blocks the screen, printing efficiency and quality decreased in the printing process. Thus, it is pivotal to explore adhesion factors from the interaction of conductive ink and screen. Herein, according to the transfer process of screen printing ink, solid-liquid wetting theory, and adhesion mechanism, we establish a liquid bridge adhesion model between two plates and obtain the functional relationship between the adhesion force and its influencing factors. Fluent software verifies the adhesion force model's conclusion to get the influence trend of the adhesion force on the ink residue. At last, by establishing a liquid bridge tensile fracture test, we gain experimental results consistent with the theoretical model and numerical simulation results. It is demonstrated that solid-liquid contact angle, tensile distance, and liquid volume are the main factors affecting the change of solid-liquid adhesion. The increase of tensile distance and contact angle will affect the adhesion force. The smaller the maximum solid-liquid adhesion during the initial stretching of the liquid bridge, the less the residual amount remained on the solid surface. By means of screen modification, the adhesion between conductive ink and screen can be reduced; meanwhile, the efficiency and quality of printed products can be improved. What's more, it also provides a valuable reference for the modification of screen printing electronics.

H.B. Fuller buys UK manufacturer of liquid adhesives, coatings and primers

H.B. Fuller Co of St Paul, Minnesota, USA, has bought Apollo, a UK-based independent manufacturer of liquid adhesives, coatings and primers for the roofing, industrial and construction markets.

A mussel-bioinspired coating strategy to licence PCL osteoinductive activity for repairing bone defects

3,4-Dihydroxyphenylalanine (DOPA) is believed to play an essential role in the solidification and adhesion of liquid mussel adhesives; this thin polymer layer very tightly adheres to the surface of scaffolds, making it stable enough to prevent it from being peeled off. Fascinatingly, the deposition of DOPA on various types of surfaces via the self-polymerization of DOPA under alkaline conditions is a simple approach for creating biomimetic coatings. In this study, DOPA derivatives were used as monomers to form primary coatings on polycaprolactone (PCL) surfaces. After that, a second chemical crosslinking method was utilized to graft alendronate (AL) on the DOPA coatings via genipin (GP) crosslinking (D-PCL@AL). X-ray photoelectron spectroscopy, Fourier transform infrared reflection and scanning electron microscopy analyses indicated that AL was distributed homogeneously on the surface of PCL. This new organic–inorganic hybridized coating could support EMSC growth and osteogenic differentiation. Additionally, animal studies were also performed to verify the function of D-PCL@AL in promoting osteogenesis. The method is simple, cheap and highly efficient, which makes it very convenient to apply on a large scale.

Liquid component effect on the dispersion and explosion characteristics of solid-liquid mixed fuel

The adhesion of liquid fuel is an important factor hindering the disengagement of solid fuel particles. And the liquid component characteristics of mixed fuel also have a significant impact on the final combustion and explosion reaction result. The liquid bridge force was detected by a self-assembled device. And the influence of the liquid fuel on the dispersion and explosion characteristics of solid–liquid fuel (nitromethane-diethyl ether-aluminum) was investigated by a laser particle size analyzer and a 20 L explosion vessel. The liquid bridge force result from the liquid fuel decreases with decreasing surface tension and liquid fuel volume effectively reduce the hindering of liquid adhesion on dispersion. And the increase in spray pressure also alleviate fuel agglomeration. The smaller the fuel particle size, the higher the explosive overpressure and the (dp/dt) max. Effectively coping with the impact of the liquid fuel adhesion on fuel dispersion could significantly accelerate the fuel reaction rate and promote energy transfer.

Scalable wear resistant 3D printed slippery liquid infused porous surfaces (SLIPS)

Surface wettability is a measure of adhesion and repulsion of liquids on a material’s surface, where surface wettability may be altered by creating a new interfacial surface between the base material and the target liquid on top. Where the interface comprises of a liquid that is locked in the pores or ridges of the base material, it is then termed as liquid infused surface (LIS). LIS alters the wettability due to the distinctive properties of the interfacial liquid which now forms the new surface. If the interfacial liquid is repellent towards polar (hydrophobic) and non-polar (oleophobic) liquids, the overall surface becomes slippery (amphiphobic) and prevents any new target liquids from adhering. This phenomenon leads to the definition of slippery liquid infused porous surfaces (SLIPS), where this term not only describes its role but also its fabrication route. Here a two-step facile method is presented to quickly transform any 3D printable polymeric material into robust SLIPS, irrespective of the wettability properties of the original polymer. The complex geometrical porosity required for locking the interfacial liquid is achieved using Fused Deposition Modelling (FDM) setup. Surface wettability characteristics of the 3D printed porous structure are then enhanced by increasing the liquid-adsorption sites where the locking of the infused interfacial (repellent) liquid takes place. The SLIPS demonstrate low rolling-off (sliding) angles with both polar and non-polar solvents of up to 2 degrees with high resistance to mechanical abrasion undergoing sliding frictional wear. The robust SLIPS as produced can be quickly scaled up using existing processes used in the laboratory.

Study on dynamic behavior of water droplet impacting on super-hydrophobic surface with micro-pillar structures by VOF method

Super-hydrophobic surfaces have been widely developed due to their unique properties, such as adhesion reduction and corrosion inhibition. It is of great significance to explore droplet dynamic process when impacting on super-hydrophobic surface, which can contribute to understanding the mechanism of super-hydrophobicity, and designing self-cleaning surfaces with ultralow adhesion and excellent corrosion resistance. Herein, three-dimensional (3D) numerical model was developed to study the droplet dynamic behaviors on super-hydrophobic NiTi surface. The volume of fluid (VOF) method was carried out to track the multi-phase flow interface and then predict droplet shape evolution during the spreading, retraction, and rebounding stages. In particular, the compression- and stretch-rebounding behaviors were investigated in detail. Based on the results of numerical simulation, the emphasis was placed on the relationship between droplet shape transformation and internal velocity/pressure distribution, revealing the mechanism of droplet morphological evolution during the impingement process. Then the experimental investigations were conducted on the planar and super-hydrophobic NiTi surfaces at different impact velocities to further verify the simulation models. It is indicated that the falling droplet would directly deposit on the planar surface, while it could fully rebound off the pillar-patterned super-hydrophobic surface. Moreover, the motion mechanism of droplet impacting on super-hydrophobic surface was elaborated, which can provide an essential instruction to effectively reduce liquid adhesion and improve anticorrosion ability for the NiTi material.

Nanofunctionalized composite-crosslinked epoxy resin for eco-friendly and robust superhydrophobic coating against contaminants

Superhydrophobic coatings are widely used in daily life and industrial applications due to their low adhesion and efficient antifouling properties. However, their eco-friendliness and robustness in high-demand environments are still inadequate for real-world applications. In this work, we report a facile method for preparing an eco-friendly and robust superhydrophobic coating (ERSC) by using a hydrophobic nano-TiO2/polydimethylsiloxane composite cross-linked epoxy resin. The micro/nano rough structure of the ERSC surface shows good water-repellent behavior, with a water contact angle of 168.7° and a sliding angle of 2.8°. This coating can withstand repeated rubbing with a finger, repetitive scratching with a knife, 60 peel-off cycles with tape, and 88 abrasion cycles with sandpaper. None of these physical abrasion methods affect the superhydrophobicity of the coating. The coating is also highly stable to acid, base, and salt treatments. Moreover, the ERSC surface directly repels the adhesion of water-based mixed liquids (such as muddy water, Coca-Cola, pig blood, and milk) and also indirectly removes solid contaminants via water droplets, exhibiting a highly efficient antifouling ability. This simple, scalable, and effective antifouling coating system shows great promise for use in various harsh environments.

Numerical study of microfluidic emulsion dynamics under the influence of heterogeneous surface wettability

Surface wettability plays a vital role in various natural phenomena and technical applications, such as coating, printing, membrane technology, microfluidic devices, and porous media flow. We numerically investigate the dynamics and stability of liquid–liquid dispersion flowing in a microfluidic channel with heterogeneous surface wettability, using a conservative phase-field lattice Boltzmann method. First, we validate the implementation of the wetting boundary conditions. We then perform three-dimensional simulations of a single drop motion immersed in another immiscible liquid in a square microchannel with alternating surface wettability: hydrophilic, hydrophobic, and again hydrophilic sections. The viscosity of the dispersed liquid (oil) is ten times higher than that of the continuous one (water), while the two liquids have equal densities. Depending on the drop length and Capillary number, calculated based on the drop velocity and the dynamic viscosity of the continuous phase, four different flow patterns are observed when the drop passes through the hydrophobic section. The distinct flow patterns include passing without any changes in drop shape or dynamics, adhesion of the dispersed liquid to the walls, phase inversion (i.e., water becomes the dispersed phase), and drop breakage. These outcomes are in close agreement with the experimental data. A detailed explanation of the choice of the numerical parameters is presented. The critical aspect of capturing the observed drop behavior is introducing an intervening thin-film of the continuous phase of at least three diffuse interface thicknesses (between the drop and channel walls).

Alkyl Chain Length Effects of Imidazolium Ionic Liquids on Electrical and Mechanical Performances of Polyacrylamide/Alginate-Based Hydrogels.

Conductive hydrogels with stretchable, flexible and wearable properties have made significant contributions in the area of modern electronics. The polyacrylamide/alginate hydrogels are one of the potential emerging materials for application in a diverse range of fields because of their high stretch and toughness. However, most researchers focus on the investigation of their mechanical and swelling behaviors, and the adhesion and effects of the ionic liquids on the conductivities of polyacrylamide/alginate hydrogels are much less explored. Herein, methacrylated lysine and different alkyl chain substituted imidazole-based monomers (IMCx, x = 2, 4, 6 and 8) were introduced to prepare a series of novel pAMAL-IMCx-Ca hydrogels. We systematically investigated their macroscopic and microscopic properties through tensile tests, electrochemical impedance spectra and scanning electron microscopy, as well as Fourier transform infrared spectroscopy, and demonstrated that an alkyl chain length of the IMCx plays an important role in the designing of hydrogel strain sensors. The experiment result shows that the hexyl chains of IMC6 can effectively entangle with LysMA through hydrophobic and electrostatic interactions, which significantly enhance the mechanical strength of the hydrogels. Furthermore, the different strain rates and the durability of the pAMAL-IMC6-Ca hydrogel were investigated and the relative resistance responses remain almost the same in both conditions, making it a potential candidate for wearable strain sensors.

Endovascular Use of Cyanoacrylate-Lipiodol Mixture for Peripheral Embolization: Properties, Techniques, Pitfalls, and Applications.

Endovascular embolization agents are particles and fluids that can be released into the bloodstream through a catheter to mechanically and/or biologically occlude a target vessel, either temporarily or permanently. Vascular embolization agents are available as solids, liquids, and suspensions. Although liquid adhesives (glues) have been used as embolic agents for decades, experience with them for peripheral applications is generally limited. Cyanoacrylates are the main liquid adhesives used for endovascular interventions and have a major role in managing vascular abnormalities, bleeding, and many vascular diseases. They can only be injected as a mixture with ethiodized oil, which provides radiopacity and modulates the polymerization rate. This review describes the characteristics, properties, mechanisms of action, modalities of use, and indications of the cyanoacrylate-Lipiodol® combination for peripheral embolization.

Lubricant-Mediated Strong Droplet Adhesion on Lubricant-Impregnated Surfaces.

Lubricant-impregnated surfaces have recently emerged as a new type of multifunctional coating with a promising capability in exhibiting low friction or contact angle hysteresis. However, lubricant-infused surfaces severely suffer from the tensile droplet-lubricant adhesion. In this study, we show that lubricant-infused surfaces allow for a strong tensile droplet adhesion, which results in the generation of an offspring residual droplet when a droplet detaches from the surface. Such tensile liquid-liquid adhesion and the corresponding liquid residue are solely mediated by the lubricant, independent of the underlying surface topography. We reveal how the lubricant film mediates droplet adhesion by measuring the maximum adhesion force and liquid residue and theoretically analyzing Laplace pressure force from the droplet shape and surface tension force depending on the contact line. Further, the presence of lubricant-induced adhesion considerably compromises the advantages of lubricant-infused surfaces in some applications. The lubricant-triggered tensile adhesion hampers the loss-free droplet transfer away from the surfaces in the photoelectrically and magnetically driven droplet manipulation. In addition, we demonstrate that the lubricant-triggered adhesion plays a dominant role in attenuating the efficiency of fog harvesting by impeding the shedding of the intercepted droplets by comparing the onset time, droplet radius, and collection efficiency. These findings advance our fundamental understanding of droplet adhesion on lubricant-infused surfaces and significantly benefit the design of lubricant-infused surfaces for various applications.

Enhancing oil recovery using silica nanoparticles: Nanoscale wettability alteration effects and implications for shale oil recovery

Enhanced oil recovery (EOR) techniques have the potential to improve recovery in unconventional shale oil reservoirs which have prolific short-term success but elusive near-to-long term outlook. The use of silicon dioxide nanoparticles for enhancing shale oil recovery has recently gained significant attention in the oil industry. However, the technique remains novel partly due to inadequate fundamental understanding of oil release mechanisms. Herein, the oil recovery potential of untreated and treated silica nanoparticles is investigated using an atomic force microscope (AFM) by studying nanoscale interactions between different crude oil functional species and substrates of pure minerals found in a shale oil reservoir. Quartz and muscovite mica (clay substitute) were employed as substrates as these are the dominant rock minerals identified in the most productive zone of Tuscaloosa Marine Shale (TMS). Thiolates of undecane (CH3) and phenyl (C6H5) compounds were used to simulate alkane and aromatic fractions of TMS crude oil respectively, while undecanoic acid (COOH) thiol was used to represent carboxylic acid found in asphaltene and resin components. Following our in-house experimental protocol for liquid cell force spectroscopy, adhesion forces and surface energies between functionalized AFM probes and mineral substrates were characterized in untreated and amino-treated silica nanoparticle dispersions. Zeta potential of respective nanofluid solutions was measured and AFM adsorption data were supported with scanning electron microscope (SEM) micrographs of TMS rock samples. Results showed that aqueous dispersions of hydrophilic silicon dioxide nanoparticles promote wettability towards a less oil-wet state by significantly lowering the adhesion force and energy barrier to spontaneously detach oil molecules from clay and quartz mineral surfaces in shale reservoirs, shown at the nanoscale with AFM studies. However, the grafting of aminosilanes onto surfaces of silica nanoparticles generally increased adhesion forces and surface energies due to surface charge effect and hydrophobicity. Findings pertinent to nanoparticle silanization were consistent in molecular interactions on mica in nanofluids but not necessarily predictable with quartz surfaces, highlighting mineralogical effects. The irreversible adsorption of silica nanoparticles was also observed. Adhesion force and energy are resolved in various intermolecular forces such as electric double layer repulsion, non-electrostatic interaction and structural forces. The scientific significance and broad engineering implications of results were comprehensively discussed in the context of previously reported core-to-field scale observations of nanofluid EOR. This study pitches new light on the scientific understanding of silica-based nanofluid EOR by probing nanoscale wetting effects of silica nanoparticles with implications for shale oil recovery. The findings herein can help for better understanding of the design of nanofluid EOR reagents and the conditions that favor application of silica nanofluid EOR.

Investigation of technological factors influencing the strength of bonded Al – alloy

Adhesive bonding makes up a significant part of rigid joints of machine elements. The aim of this study was to investigate the contamination effect of moisture and oil on the bond strength of aluminium alloy 2024 T3 bonded by film and liquid adhesives using mechanical and chemical surface preparation methods. Two types of joints were used: homogeneous (Al-Al) and heterogeneous (Al-GFRP) ones. Surface preparation highly increased surface roughness Ra. The surfaces were moistened with deionized water and mineral oil and glued after a constrained time delay (outlife). Tensile shear strength tests of the joints showed higher strength of the chemically prepared surfaces by gluing with film adhesive. Contrarily mechanically prepared surfaces were stronger with liquid adhesive. Film adhesive seemed less sensitive to surface contamination in general.

P‐42: New Technology with Best of Both Tape and Liquid Adhesive

The technology is able to provide good intermediate performance from liquid and tape. Thermo reversible material is able to follow large step, make wide range modulus, and make good uniformity after slit die coating. In addition, the technology keep good optical performance.

Convergent synthesis of diversified reversible network leads to liquid metal-containing conductive hydrogel adhesives

Many features of extracellular matrices, e.g., self-healing, adhesiveness, viscoelasticity, and conductivity, are associated with the intricate networks composed of many different covalent and non-covalent chemical bonds. Whereas a reductionism approach would have the limitation to fully recapitulate various biological properties with simple chemical structures, mimicking such sophisticated networks by incorporating many different functional groups in a macromolecular system is synthetically challenging. Herein, we propose a strategy of convergent synthesis of complex polymer networks to produce biomimetic electroconductive liquid metal hydrogels. Four precursors could be individually synthesized in one to two reaction steps and characterized, then assembled to form hydrogel adhesives. The convergent synthesis allows us to combine materials of different natures to generate matrices with high adhesive strength, enhanced electroconductivity, good cytocompatibility in vitro and high biocompatibility in vivo. The reversible networks exhibit self-healing and shear-thinning properties, thus allowing for 3D printing and minimally invasive injection for in vivo experiments.

668 Fixation of Split-Thickness Skin Grafts with Liquid Adhesive and Fibrin Glue in Place of Staples

Abstract Introduction A critical component of split-thickness skin grafting is the fixation of the skin graft to the wound site. Graft displacement can result in graft failure, especially during the initial 48–72 hours following application. The most common method of securing grafts is with the use of staples, sometimes with the addition of fibrin glue in order to aid both graft adhesion and homeostasis. The use of staples, however, is associated with significant levels of patient discomfort, especially during staple removal. A possible alternative to staples is the use of liquid adhesives, in combination with steri-strips, to anchor the edges of skin grafts to intact skin. Certain liquid adhesives, such as gum-based resins, are cheaper to use than staples and offer the potential to secure small split-thickness skin grafts without the associated pain of staples. In this pilot study, we examined the effectiveness of using a combination of gum-based resin (Gum Mastic-Storax-Msal-Alcohol), fibrin glue, and steri-strips to secure partial-thickness grafts in 8 patients without the use of staples or sutures. Methods Patients were included in the study who required split-thickness skin grafts to treat wounds involving less than or equal to 15% total surface body area and whose wounds were not located in areas prone to graft displacement, such as the axilla and groin. For each patient, skin grafts were secured using fibrin glue (sprayed over the entire wound), and a combination of liquid adhesive and steri-strips applied around the wound perimeter. The success of each graft was determined by the percentage of graft take. Results From January 1st, 2020 to April 30th, 2020, 8 patients were identified who fit the inclusion criteria. Five of the patients received grafts to their lower extremities, two patients received grafts to their upper extremities, and one of the patients received a graft to the torso. The average wound site that was grafted was 116.7 cm2. Average graft take among the 8 patients was 96.9%, with a range of 90%-100%. No complications at the graft site were noted, such as hematomas or any other event that resulted in graft displacement or failure. Conclusions The results of the study demonstrate that a combination of liquid adhesive, fibrin glue, and steri-strips, can be used as an effective alternative to staples in small split-thickness skin grafts. The use of liquid adhesive in place of staples was advantageous because it eliminated to need for staple removal, which resulted in less discomfort for the patient and less work for the nursing staff.

Application of Glow Discharge Plasma for Cleaning (Activation) and Modification of Metal Surfaces while Welding, Brazing, and Coating Deposition

As known, the surface phenomena play a crucial role in the formation of strong interatomic bonds while joining dissimilar materials and the deposition of metal films. Thus, the presence of various contaminants, including oxides, on the metal surface reduces drastically the metal surface energy, thereby, preventing the diffusion processes in the contact zone and wetting them with liquid solder and adhesion of condensed films on the substrate surface. As a result, the processes of cleaning (activating) of metal surfaces before welding or coatings’ deposition begin to play a significant role. In some cases, metal surfaces have to be modified in order to give them the desired properties. Recently, for activation and modification of surfaces before welding and coatings’ deposition, gas-discharge plasma of abnormal glow discharge is widely used. The latter allows treating the surfaces of different configurations, including internal cavities, and various areas from units to tens of thousands of square centimetres. This review contains the results of research on the activation and modification of metal surfaces with low-energy ions (< 10 keV) initiated in the plasma of an abnormal glow discharge for welding, brazing, and coatings’ deposition. Particularly, we present results of studies of ion treatment with the glow discharge surface of samples, which are made of steels С45 and DC04, a number of active metals and alloys as well as chromium-containing steels 41Cr4, X20Cr13, and X6CrNiTi18-10, which possess the chemically and thermally stable Cr2O3 oxides on their surfaces. The decisive influence on the efficiency of purification and modification of metal surfaces with glow discharge by means of such regime parameters as electrode voltage, discharge current density, working chamber pressure, and ion exposure time is indicated. The optimal values of these parameters, in most cases, are determined by the technological conditions of the process and vary in the following ranges: U = 1500–3500 V, J = 0.4–1 mA/cm2, P = 3.99–7.98 Pa, t = 120–300 s, respectively.

Effect of surface roughness and temperature on stainless steel - Whey protein interfacial interactions under pasteurisation conditions

The effects of the surface characteristics of 316L stainless steel (SS316L), including chemical composition before and after foulant deposition, surface roughness, and wall temperature, on both the liquid-solid and the solid-solid interfacial interactions have been investigated using contact angle measurements and atomic force microscopy respectively. Wettability of the metal surface was favoured by increased surface roughness (in the range-limited for food contact applications) and wall temperature (within the temperature range used for pasteurisation). A fine surface finish (i.e. mirror) could be an effective intervention to reduce liquid adhesion and the subsequent foulant deposition, especially under thermal treatment. The surface free energy (SFE) of SS316L and its polar and disperse components remained constant from ambient to pasteurisation temperatures (<80°C). However, as fouling develops, the surface free energy evolved: upon foulant deposition, SFE decreased. An increased polarity (3.4% from 25 to 80°C) of the fouled surface could be related to the exposure the hydrophobic core of reversibly adsorbed β-Lactoglobulin toward the foulant-air interface. Both surface adhesion and Young's modulus at sub-micron spatial resolution confirmed that the packing within the foulant and molecular orientation on the foulant surface were affected by the temperature of the underlying substrate. Temperature also affected the wetting behaviour of cleaning solutions on surface foulant; as the surface temperature increased from 25°C to 75°C, the contact angle on WPC increased, suggesting an enhanced surface hydrophobicity. Overall, this work highlights the importance of surface parameters on governing the interfacial interactions that are competing for the control of the complex fouling phenomena.