Dry Adhesives Research Articles

Adhesion theory and model for air humidity impact on dust emission

It has been suggested that air humidity influences dust emission under very dry conditions and adhesion might be the responsible process which changes the binding between soil particles. The process of adhesion is so far poorly understood and difficult to quantify. Here, a critical examination of the relevant studies is provided, and an adhesion model is proposed. Both isothermal-kinematic and diffusion processes can limit the soil liquid–water and water–vapor exchange in soil, but for the particle size range concerned in aeolian studies, diffusion appears to be the limiting process. The model shows that soil moisture in the topsoil layers is positively correlated with air humidity, but with delays of several hours. The model performance is influenced by several parameters but is particularly sensitive to the equilibrium soil water–vapor content. This implies that soil microscopic properties can strongly influence adhesion. A new formulation of soil water retention function covering the entire soil moisture range is also proposed, which links soil water retention function and pore size distribution. Using a relationship between soil particle-size and pore-size distributions, an adhesion-affected grain size can be estimated, which defines the upper size limit of soil particles influenced by soil moisture. This study explains how air humidity influences soil moisture through adhesion and dust emission and why low air humidity promotes the emission of finer dust particles.

THE IMPACT OF WATER-BASED ZINC-FLAKE COATING ON BOLT CORROSION PERFORMANCE

In this study, the coatability of bolts with water-based zinc flake coating for the conditions in which electrostatic coating is not convenient was examined. In the sandblasting stage, two different types of sand were used to determine the impact of the sand type. When the results were compared, no significant difference was observed between the use of the two sand types. However, stainless-steel bolt usage was found to be more appropriate in terms of the filter maintenance of the sandblasting machine. At zinc-flake coating stage, the qualities of the bolts coated twice and coated thrice were compared to determine the impact of the coating number. According to tests of the dry adhesion, no coating error was detected on the both bolt surfaces. The corrosion resistance test showed that, the bolts with 24 g m-2 and 36 g m-2 coating weight had high corrosion resistance.

Dynamically reprogrammable stiffness in gecko-inspired laminated structures

Adaptive structures are of interest for their ability to dynamically modify mechanical properties post fabrication, enabling structural performance that is responsive to environmental uncertainty and changing loading conditions. Dynamic control of stiffness is of particular importance as a fundamental structural property, impacting both static and dynamic structural performance. However, existing technologies necessitate continuous power to maintain multiple stiffness states or couple stiffness modulation to a large geometric reconfiguration. In this work, reversible lamination of stiff materials using gecko-inspired dry adhesives is leveraged for bending stiffness control. All stiffness states are passively maintained, with electrostatic or magnetic actuation applied for ∼1 s to reprogram stiffness. We demonstrate hinges with up to four passively maintained reprogrammable states decoupled from any shape reconfiguration. Design guidelines are developed for maximizing stiffness modulation. Experimentally, the proposed method achieved a stiffness modulation ratio of up to 14.4, with simulations showing stiffness modulation ratios of at least 73.0. It is anticipated that the stiffness reprogramming method developed in this work will reduce energy requirements and design complexity for adaptation in aerospace and robotics applications.

Effect of Different Passivation Treatments on Alkali Zn-Ni Coatings: Corrosion Resistance and Adhesion Performance of Geomet 321 and ML Black Coatings

This study aims to improve the corrosion properties of (AISI 1040) materials used in the automotive industry. For this purpose, two different coating techniques were applied to the same surface. As part of the research, different passivation processes (transparent, blue, yellow, and black) were applied to alkaline Zn-Ni coatings. Geomet 321 and Geomet ML Black coatings were deposited on the passivation layer to form a double-layer coating. In order to investigate the adhesion and corrosion effects of these coatings, a dry adhesion test, a water test, a humidity test, and a salt spray test were carried out, and cross-cut adhesion tests were carried out after each corrosion test. After all these tests, rust formation was analysed by visual analysis, and atomic weight percentages and coating thicknesses were examined by X-ray. The transparent passivation after the Zn-Ni coating fully satisfied both adhesion and corrosion protection requirements for 321 and ML Black coatings. No red rust formation was observed on the coating samples after the test; only partial white rust formation was observed, and no peeling of the coating layer was detected in the adhesion tests. As a result, the optimum result of the passivation processes used for Geomet 321+ML Black coatings applied after the Zn-Ni + passivation process was obtained with transparent passivated Zn-Ni coatings. Even after 1200 hours, no red rust was observed in passivated Zn-Ni coating+ Geomet 321+ Geomet ML Black.

Bionic Adhesion Systems: From Natural Design to Artificial Application

AbstractCreatures in nature perform a variety of activities through adhesion behavior, including moving flexibly and quickly on inclined and vertical walls and even ceilings. Studying the physical and chemical mechanisms underlying their adhesion behaviors can provide effective templates for applications such as climbing robots, grippers, and medical devices. This review summarizes various major types of adhesion that creatures rely on and their morphological structures that enhance adhesion, in addition to discussing their inspiration regarding the design of bionic adhesion systems. First, different adhesion types adopted by creatures in various natural environments are introduced, and the adhesion mechanisms and their theoretical models are summarized. Subsequently, the convergent evolution exhibited in biological adhesion structures is summarized from three perspectives: size limitation, compliance, and fluid transport. The development of the bionic design process wherein researchers imitate the natural biological adhesion process to create artificial adhesives is then presented regarding three mechanisms: chemical bonding adhesives, fiber arrays, and suckers. Fiber arrays are further divided into dry adhesives and wet adhesives. Finally, the shortcomings of the existing bionic adhesion systems and future trends are summarized.

Electrothermal Dry Adhesives with High Adhesion Under Low Temperatures Based on Tunable Stiffness

AbstractBioinspired dry adhesives relying on van der Waals interactions have shown great potential in object manipulation and climbing robots. Although substantial progress has been made in dry adhesives for extreme environments (such as vacuum and microgravity), robust adhesion at low temperatures, i.e., typical scenes in space or polar environments, is rarely achieved. Here, an electrothermal dry adhesive (EDA) based on tunable stiffness for low‐temperature environments is proposed, which can be reversibly transformed between the soft and rigid state in low‐temperature environments due to the electrothermal effect. The former is beneficial for conformal contact, while the latter is convenient for interfacial stress homogenization in the grasping stage. According to the adhesion strategy comprising soft contact followed by rigid gripping, the EDA demonstrates the adhesion of 1063 kPa at −90 °C, i.e., 1022 times higher than conventional polydimethylsiloxane (PDMS) adhesives. Moreover, the EDA requires an energy supply (6 W at −90 °C) only during pressing, subsequently changing to the rigid state with no power consumption, which requires relatively low electrical energy compared to continuous heating methods. Such adhesion strategy extends the workable temperature of dry adhesives to −90 °C, opening up a new avenue for developing dry adhesives for harsh environments.

Enhancing concrete performance using protective coating fabricated by recycled waste material

The motivation behind this research is to enhance concrete using a coating fabricated from waste materials. Polyethylene terephthalate (PET) was added to asphalt (AP) cement of 60/70 penetration grade at different percentages. Scanning electron microscope (SEM) images show that 6% PET is the optimum mix proportion, and then ternary blends were done by mixing the prepared AP/PET with nano silica (nS) at different ratios (0.5, 1, 1.5, 2, and 2.5) wt./wt. The prepared coatings were evaluated by determining drying time, dry film thickness (DFT), adhesion strength, impact resistance, and flexibility. The formulated coatings were applied to concrete substrates, and the performance of coated concrete cubes was examined by determining water absorption, contact angle, and chloride diffusion. The durability of coated concrete was evaluated by measuring the changes in compressive strength after immersion in both sulfuric acid and sodium chloride solutions separately. The study proved the eco-efficient use of PET waste bottles in protective coating preparation, and the experimental results detected that nS has a significant mechanism for improving coating performance as follows; drying time of AP/PET-2 reduced with 61% as compared to AP/PET, the increment of DFT of AP/PET-2 was 25%, and adhesion strength was improved by 90%. On the same time, silica nano particles are mainly contributes for enhancing coated concretes. Where water absorption reduced with 75%, contact angle increased by 55%, and chloride permeability resistance enhanced to 40%. Finally, improvement durability of coated concrete was 25% and 20% after immersion for 28 d in both sulfuric (3%) acid and sodium chloride (5%) solutions, respectively.

Recent Progress on the Use of Stimulus-Responsive Materials for Dry Adhesive Applications.

Stimulus-responsive dry adhesives, inspired by the adhesive mechanisms displayed by the fibrillar structures present on the feet of geckos, have emerged as a promising area of research for applications such as robotic grippers and climbing robots. These stimulus-responsive dry adhesives exhibit some unique capabilities, as their ability to adhere to and detach from surfaces can be controlled with the help of an external stimulus. For example, studies have developed magnetic field-responsive dry adhesives and show that the adhesion of these materials can be turned on and off by controlling the applied magnetic field. Light-responsive adhesives have also been developed and shown to reverse their adhesion using infrared light as the stimulus. Such materials show tremendous promise in pick-and-place systems for handling delicate objects and microelectronic products. The focus of this article is to review the stimulus-responsive materials that have been used to develop dry adhesives. The mechanisms adopted by these stimulus-responsive materials to switch their adhesion are discussed. Applications of stimulus-responsive dry adhesives are presented, and last, the future perspective of these materials is discussed.

Laser belt processed micropillars with microporous structure and nanoparticles to control the surface wettability of superhydrophobic Inconel 718 alloy

The superhydrophobic surface features such as self-cleaning, keeping dry and low adhesion have wide application prospects in biotechnology, medicine, and engineering. As a superhydrophobic surface machining method, pulsed laser ablation has attracted wide attention due to its high precision. However, due to the efficiency, pulsed laser composite processing technology has gradually developed into the main preparation method for superhydrophobic surfaces. A effective machining method (laser belt collaborative processing) for superhydrophobic surface preparation was proposed in this paper. The microgroove surface could be prepared by using a pyramid abrasive belt with regular consistency of abrasive height and a high precision picosecond laser. After rotating the workpiece 90°, the micropillar surface could be formed by machining again. The height of micropillars increases significantly with the increase of the laser power. There are multiscale structures on the micropillar surface, including micropores, microaggregates, and nanoparticles. With the design spacing of the micropillar increasing to 80 μm, the contact angle reaches a maximum value of 153.8° The adsorption of carbon elements and the low solid-liquid contact fraction are beneficial to the enhancement of surface hydrophobicity. The superhydrophobic micropillar surface is extremely stable, which can withstand various harsh treatments/environments, such as sandpaper abrasion, tape peeling. A new processing method for superhydrophobic micropillar surface preparation was proved, which is conducive to the application of superhydrophobic surfaces.

Effect of high-temperature mechanochemistry method modified TiO2 on the dispersibility and corrosion resistance of TiO2-epoxy coatings

PurposeThe purpose of this paper is to enhance the compatibility of titanium dioxide in epoxy resins and thus the corrosion resistance of the coatings.Design/methodology/approachIn this work, TiO2 was modified by the mechanochemistry method where mechanical energy was combined with thermal energy to complete the modification. The stability of modified TiO2 in epoxy was analyzed by sedimentation experiment. The modified TiO2-epoxy coating was prepared, and the corrosion resistance of the coating was analyzed by open circuit potential, electrochemical impedance spectroscopy and neutral salt spray test.FindingsHigh-temperature mechanical modification can improve the compatibility of TiO2 in epoxy resin. At the same time, the modified TiO2-epoxy coating showed better corrosion resistance. Compared to the unmodified TiO2-epoxy coating, the coating improved the dry adhesion force by 61.7% and the adhesion drop by 33.3%. After 2,300 h of immersion in 3.5 Wt.% NaCl solution, the coating resistance of the modified TiO2 coating was enhanced by nearly two orders of magnitude compared to the unmodified coating.Originality/valueThe authors have grafted epoxy molecules onto TiO2 surfaces using a high-temperature mechanical force modification method. The compatibility of TiO2 with epoxy resin is enhanced, resulting in improved adhesion of the coating to the substrate and corrosion resistance of the coating.

Machine Learning-Based Shear Optimal Adhesive Microstructures with Experimental Validation.

Bioinspired fibrillar structures are promising for a wide range of disruptive adhesive applications. Especially micro/nanofibrillar structures on gecko toes can have strong and controllable adhesion and shear on a wide range of surfaces with residual-free, repeatable, self-cleaning, and other unique features. Synthetic dry fibrillar adhesives inspired by such biological fibrils are optimized in different aspects to increase their performance. Previous fibril designs for shear optimization are limited by predefined standard shapes in a narrow range primarily based on human intuition, which restricts their maximum performance. This study combines the machine learning-based optimization and finite-element-method-based shear mechanics simulations to find shear-optimized fibril designs automatically. In addition, fabrication limitations are integrated into the simulations to have more experimentally relevant results. The computationally discovered shear-optimized structures are fabricated, experimentally validated, and compared with the simulations. The results show that the computed shear-optimized fibrils perform better than the predefined standard fibril designs. This design optimization method can be used in future real-world shear-based gripping or nonslip surface applications, such as robotic pick-and-place grippers, climbing robots, gloves, electronic devices, and medical and wearable devices.

Smart Manipulation of Complex Optical Elements via Contact-adaptive Dry Adhesives.

The implementation of complex, high-precision optical devices or systems, which have vital applications in the aerospace, medical, and military fields, requires the ability to reliably manipulate and assemble optical elements. However, this is a challenging task as these optical elements require contamination-free and damage-free manipulation and come in a variety of sizes and shapes. Here, a smart, contact-adaptive adhesive based on magnetic actuation is developed to address this challenge. Specifically, the surface bio-inspired adhesives made of fluororubber facilitate contamination-free and damage-free adhesion. The stiffness modulation of packaged magnetorheological grease based on the magnetorheological effect endows the smart adhesive with a high conformability to the optical elements in the soft state, a high grip force in the stiff state, and the ability to quickly release the optical elements in the recovered soft state. The smart adhesive provides a versatile solution for reliably and quickly manipulating and assembling multiscale optical elements with planar or complex 3D shapes without causing surface contamination or damage. These extraordinary capabilities are demonstrated by the manipulation and assembly of various optical elements, such as convex/concave/ball lenses and extremely complex-shaped light guide plates. The proposed smart adhesive is a promising candidate for conventional optical element manipulation technologies.

Water-repellent and self-attachable flexible conductive patch

Achieving exceptional water-repellency and reliable reversible adhesion is crucial for the development of wearable flexible electronics. However, simultaneously achieving these properties presents a significant challenge, as water-repellency requires maximizing the presence of air while robust adhesion necessitates enhancing the solid fraction. In this study, we present a flexible and transparent conductive patch that addresses this challenge by offering simultaneous robust superhydrophobicity and strong adhesion in both dry and wet conditions. The device incorporates a unique combination of overhang micropillars, microgrids and a percolating network of carbon nanotubes. The proposed patch demonstrates outstanding water repellency with a contact angle exceeding 150°, while delivering impressive dry adhesion (>200 kPa) and wet adhesion (>150 kPa) performance. Furthermore, the device exhibits tunable electrical conductivity and optical transmittance.

Scaling Effect of Dry Adhesion for Microfibrils and Transition Size to Flaw Insensitivity

Abstract The mechanics of detachment (e.g., a cylindrical fibril separating from a dissimilar substrate) has been treated in the perspectives of contact mechanics and fracture mechanics theory along with numerical simulations, but systematic experimental studies on the adhesion of an individual microfibril is still scarce. In this work, we conducted a detailed experiment on the adhesion tests of individual cylindrical microfibrils, within a large range of varying diameters from 4 to 400 μm, made of three different polyurethanes with moduli among ∼1–40 MPa. We confirmed the scaling effect of an individual microfibril, i.e., the adhesion σad of the individual fibril scales with fibrillar diameters D with an exponent of ∼ −0.4 to −0.45. As the fibrillar diameter is reduced below 10 μm, the adhesion becomes unchanged and size insensitive. This result is in good agreement with the theoretical predictions. Furthermore, the effects of the Young’s modulus and retraction rates during the adhesion tests on the adhesion strength were also investigated. Our experimental work will provide a guide for the optimal design of the micron-scale surfaces with improved adhesion.

Thermodynamic Properties of Aggregate Coated by Different Types of Waste Plastic: Adhesion and Moisture Resistance of Asphalt-Aggregate Systems

The utilization of acidic aggregates in hot-mix asphalt (HMA) is often inevitable due to the limited supply of locally available aggregates, posing a potential threat of moisture damage to asphalt pavements. In this regard, the use of urban waste plastic to coat the low-quality aggregates is a promising way to improve the moisture resistance. This study fundamentally evaluated the compatibility between asphalt and plastic-coated aggregate by measuring surface energy, and for the first time compared the effects of different types of waste plastic including high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polypropylene (PP). The plastic-coating significantly altered the chemistry of aggregate surface by increasing the nonpolar components and reducing the polar components. Such changes remarkably increased the dry adhesion energy between asphalt and aggregate and enhanced the wettability of aggregate. For the acidic aggregates, the polymeric treatment could decrease the value of wet adhesive, which indicated the debonding tendency in the presence of water was reduced. Finally, the energy ratios of the asphalt-aggregate combinations significantly increased by the surface pretreatment, which proved the effect of waste plastic coating on improving the moisture damage resistance of asphalt mixtures. By comparison, the HDPE coating was the most effective way to enhance the compatibility with asphalt, followed by PP and LDPE coatings. The PVC and PET coatings were investigated as the least effective way. This study cannot only contribute to the potential large-scale utilization of waste plastic but also remove the obstacles of using large quantities of acidic natural aggregate in asphalt pavements.

Examination of gecko-inspired dry adhesives for heritage conservation as an example of iterative design and testing process for new adhesives

AbstractRarely within the conservation of cultural heritage have conservation professionals been lucky enough to have materials custom-designed to meet their requirements. Most of the time the field must adapt solutions developed for other applications. The research presented here was initiated as part of a long-term aim to develop new adhesives for heritage conservation. Gecko-inspired dry adhesives (GDAs) are polymer tapes with micropatterns that are based on the adhesive properties of the pads of gecko lizard feet: they have strong normal and shear adhesion with low peel adhesion. They present potentially versatile and reversible adhesives for heritage conservation applications; which do not require solvents for activation or for removal, and do not migrate or off-gas. In nature, geckos can adhere with their feet to any surface they walk on. This is possible because of micro- and nanostructures on their feet that attach to surface via van der Waals forces. Practical studies aimed at comprehensively assessing their properties, and biomimetic solutions in heritage conservation are still sparse at present. This research has the objective of assessing GDAs properties by mechanical testing of adhesive joints, as well as physical and chemical characterisation of the materials used. The research has also included a museum case study and a two-year natural ageing test. The testing has shown that the GDAs can perform very well as an adhesive patch on the reverse of gelatine-based photographs, achieving shear forces between 0.80 N and 48.10 N on 8 cm2 lap joints (depending on the type of the GDA) and peel forces between 0.20 N and 0.47 N over 2 cm of peel front. This is lower than forces exceeding 1 N recorded in widely available pressure-sensitive tapes. This shows that GDAs may have the potential of a sufficiently strong, yet easily removable adhesive that works well on materials widely present in museum collections.

Applying the 12 Principles of Green Engineering in Low TRL Electronics: A Case Study of an Energy-Harvesting Platform

Energy harvesting has been identified as a key enabling technology for the Internet of Things as it allows a battery-less functioning of electronic devices. While the use of ambient sources of energy is commonly seen as sustainable due to their renewable nature, raw material consumption and recyclability need to be assessed to ensure true sustainability. This is especially relevant in electronics, due to their high complexity stemming from the variety of components and materials in their composition. This work presents the case study of the application of the 12 Principles of Green Engineering to an energy-harvesting platform in the early technology development phase. Specifically, the technological areas of design for disassembly, materials for substitution, fabrication efficiency, and manufacturing processes that enable the use of recycled materials have been evaluated. This has allowed us to identify hazardous raw materials and recommend their substitution. Further recommendations include the adoption of mechanical fixtures to fasten lump components. Additional strategies have been identified but their application has been found out of reach of the technology developers, such as the increase in the manufacturing batch size or the inclusion of solvent recycling, which can only be implemented at larger manufacturing scales. Further strategies, such as the use of recycled Si wafers or dry adhesives as fixtures, represent future solutions for the reduction in the environmental impact which require further R&D efforts from different disciplines. This highlights the need for holistic and multidisciplinary research efforts to fully achieve the circular design.

Predicting adhesion strength of micropatterned surfaces using gradient boosting models and explainable artificial intelligence visualizations

Fibrillar dry adhesives are widely used due to their effectiveness in air and vacuum conditions. However, their performance depends on various factors. Previous studies have proposed analytical methods to predict adhesion strength on micro-patterned surfaces. However, the method lacks interpretation on which parameters are critical. This research utilizes gradient-boosting machine learning (ML) algorithms to accurately predict adhesion strength. Additionally, explainable machine learning (XML) methods are employed to interpret the underlying reasoning behind the predictions. The analysis demonstrates that gradient boosting models achieve a high correlation coefficient (R > 0.95) in accurately predicting pull-off force on micro-patterned surfaces. The use of XML methods provides insights into the importance of features, their interactions, and their contributions to specific predictions. This novel, explainable, and data-driven approach holds potential for real-time applications, aiding in the identification of critical features that govern the performance of fibrillar adhesives. Furthermore, it improves end-users' confidence by offering human-comprehensible explanations and facilitates understanding among non-technical audiences.

Colorimetric CO2 Indicators.

Carbon dioxide, CO2, is an essential part of life, in that through green plant photosynthesis it is used to generate food and fuel and is generated in both aerobic and anaerobic respiration. Industrially, it is used in fire extinguishers, supercritical fluid extractions, and food packaging. Environmentally, it is in the atmosphere, hydrosphere, and biosphere and is responsible for global warming and the acidification of the oceans. The monitoring of CO2 in the gas phase is usually carried out using FTIR spectroscopy, whereas the measurement of dissolved CO2 usually involves an electrochemical device. Excitingly, the most recent forms of CO2 indicators appear to offer significant advantages over current methods, such as simplicity, low cost, and portability. This Account highlights the work of the Mills group on transforming CO2 colorimetric indicator technology from the usual water-based (i.e., "wet") indicator form to dry CO2-sensitive inks, pigments, plastics, and adhesives. Initially, the basic theory associated with colorimetric CO2 indicators is described, and the simple relationship between indicator absorbance and the partial pressure of CO2, PCO2, established. The early work on CO2-sensitive inks is then described, where such inks comprise a hydrophilic pH-sensitive dye anion, coupled with a lipophilic quaternary ammonium cation, dissolved in a nonaqueous solution of a polymer which, when cast, forms a dry ink film that gives a reversible color response when exposed to CO2 both in the gas phase and dissolved in solution. The ability to tune the sensitivity of a CO2 ink film to the desired application through the judicious choice of the pH indicator dye and base concentration is described. The dependence of the sensitivity of a CO2 ink film on temperature is used to create a temperature indicator, and the ability to tune the ink, to respond to high levels of CO2, is used to create a fizziness indicator for carbonated drinks. Very sensitive CO2 inks are used to make a vacuum and a general air-pressure indicator. The more recent development in CO2 indicator technology is described in which CO2 inks are used to coat silica particles to make a range of different CO2-sensitive pigments, which, when incorporated into a plastic, through extrusion, produce a range of novel CO2-sensitive plastic films that have many notable advantages over their ink film counterparts. Examples are then given of such plastic films being used for dissolved CO2 measurements in salt water, for food packaging, and as an early wound-infection indicator. Finally, the recent incorporation of a CO2-sensitive pigment into a pressure sensitive adhesive to make an after opening freshness tape is described briefly. Although most commercial CO2 indicators are assessed by eye and so are limited to qualitative analysis, this work shows that colorimetric CO2 indicators can be used for quantitative analysis through absorbance measurements. Nowadays, such measurements can be readily made using just a digital camera and color analysis software via digital camera colorimetry, DCC, which is likely to have a significant impact on the widespread use of the CO2 indicators described herein, their commercial viability, and their potential areas of application.

Tuning Dry and Wet Adhesion with a Branched Supramolecular Polymer Solution

Endowing adhesives with both dry and wet adhesion to surfaces from hard substrates to soft biological tissues is challenging. Herein, a branched supramolecular polymer is introduced in dry‐ and wet‐crosslinking forms to adaptively achieve dry and wet interfacial adhesion. The branched supramolecular polymer (PAMU) with multiple pendant functional moieties is prepared by one‐pot reversible addition‐fragmentation chain transfer polymerization. The PAMU polymer solution can firmly adhere to glass sheets after the water evaporates. The aqueous solution of PAMU polymer with residual double bonds can be further polymerized to form a wet crosslinking network. The hydrogen bonding moieties endow the supramolecular network with self‐healing properties, while the in situ polymerization of the PAMU polymer leads to stable adhesion to wet tissues. This study provides a promising approach to develop supramolecular adhesives for versatile adhesion applications.