Barnacle Cement Proteins-Inspired Tough Hydrogels with Robust,Long-Lasting,and Repeatable Underwater Adhesion

The development of adhesives that can achieve robust and repeatable adhesion to various surfaces underwater is promising; however, this remains a major challenge primarily because the surface hydration layer weakens the interfacial molecular interactions. Herein, a strategy is proposed to develop tough hydrogels that are robust, reusable, and long-lasting for underwater adhesion. Hydrogels from cationic and aromatic monomers with an aromatic-rich composition inspired by the amino acid residuals in barnacle cement proteins are synthesized. The hydrogels are mechanically strong and tough (elastic modulus 0.35 MPa, fracture stress 1.0 MPa, and fracture strain 720%), owing to the interchain π–π and cation–π interactions. In water, the hydrogels firmly adhere to diverse surfaces through interfacial electrostatic and hydrophobic interactions (adhesion strength of 180 kPa), which allows for instant adhesion and reversibility (50 times). Moreover, the hydrogel shows long-lasting adhesion in water for months (100 days). Novel adhesive hydrogels may be useful in many applications, including underwater transfer, water-based devices, underwater repair, and underwater soft robots.     

Ultracompliant Hydrogel‐Based Neural Interfaces Fabricated by Aqueous‐Phase Microtransfer Printing

Hydrogel‐based electronics are ideally suited for neural interfaces because they exhibit ultracompliant mechanical properties that match that of excitable tissue in the brain and peripheral nerve. Hydrogel‐based multielectrode arrays (MEAs) can conformably interface with tissues to minimize inflammation and improve the reliability to enhance signal transduction. However, MEA substrates composed of swollen hydrogels exhibit low toughness and poor adhesion when laminated on the tissue surface and also present incompatibilities with processes commonly used in MEA fabrication. Here, a strategy to fabricate an ultracompliant MEA is described based on aqueous‐phase transfer printing. This technique employs redox active adhesive motifs in hygroscopic polymer precursors that simultaneously form hydrogels through sol–gel phase transitions and bond to materials in the underlying microelectronic structures. Specifically, in situ gelation of four‐arm‐polyethylene glycol‐grafted catechol [PEG‐Dopa]₄ hydrogels induced by oxidation using Fe³⁺ produces conformal adhesive contact with the underlying MEA, robust adhesion to electronic sub‐structures, and rapid dissolution of water‐soluble sacrificial release layers. MEAs are integrated on hydrogel‐based substrates to produce free‐standing ultracompliant neural probes, which are then laminated to the surface of the dorsal root ganglia in feline subjects to record single‐unit neural activity.     

An Anti-Freezing,Ambient-Stable and Highly Stretchable Ionic Skin with Strong Surface Adhesion for Wearable Sensing and Soft Robotics

Natural living systems such as wood frogs develop tissues composed of active hydrogels with cryoprotectants to survive in cold environments. Recently, hydrogels have been intensively studied to develop stretchable electronics for wearables and soft robots. However, regular hydrogels are inevitably frozen at the subzero temperature and easily dehydrated, and have weak surface adhesion. Herein, a novel hydrogel-based ionic skin (iSkin) capable of strain sensing is demonstrated with high toughness, high stretchability, excellent ambient stability, superior anti-freezing capability, and strong surface adhesion. The iSkin consists of a piece of ionically and covalently cross-linked tough hydrogel with a thin bioadhesive layer. With the addition of biocompatible cryoprotectant and electrolyte, the iSkin shows good conductivity in wide ranges of relative humidity (15–90%) and temperature (−95–25 °C). In addition, the iSkin can adhere firmly to diverse material surfaces under different conditions, including cloth fabric, skin, and elastomers, in both dry and wet conditions, at subzero temperature, and/or with dynamic movement. The iSkin is demonstrated for applications including strain sensing on both human body and winter coat, human–machine interaction, motion/deformation sensing on a soft gripper and a soft robot at extremely cold conditions. This work provides a new paradigm for developing high-performance artificial skins for wearable sensing and soft robotics.     

A Universal Strategy for Tough Adhesion of Wet Soft Material

Achieving adhesion between hydrogels and diverse materials in a facile and universal way is challenging. Existing methods rely on special chemical or physical properties of the hydrogel and adherends, which lead to limited applicability and complicated pretreatments. A stitch‐bonding strategy is proposed here by introducing a polymer chain with versatile functional group and triggerable crosslinking property inspired by catechol chemistry. The polymer chain can stitch the hydrogel by forming a network in topological entanglement with the preexisting hydrogel network, and directly bond to the adherend surface by versatile chemical interactions. Through this, the polymer chain solution works as a universal glue for facile adhesion of hydrogels to diverse substrates like metals, glasses, elastomers, plastics, and living tissues, without requiring any chemical design or pretreatment for the hydrogel and adherends. The adhesion energy between polyacrylamide hydrogel and diverse substrates can reach 200–400 J m^?2, and it can reach ≈900 J m^?2 with a toughened polyacrylic acid polyacrylamide hydrogel. The mechanism of stitch‐bonding strategy is illustrated by studying various influence factors.     

A Novel Double‐Crosslinking‐Double‐Network Design for Injectable Hydrogels with Enhanced Tissue Adhesion and Antibacterial Capability for Wound Treatment

Most photocrosslinkable hydrogels have inadequacy in either mechanical performance or biodegradability. This issue is addressed by adopting a novel hydrogel design by introducing two different chitosan chains (catechol‐modified methacryloyl chitosan, CMC; methacryloyl chitosan, MC) via the simultaneous crosslinking of carbon–carbon double bonds and catechol‐Fe³⁺ chelation. This leads to an interpenetrating network of two chitosan chains with high crosslinking‐network density, which enhances mechanical performance including high compressive modulus and high ductility. The chitosan polymers not only endow the hydrogels with good biodegradability and biocompatibility, they also offer intrinsic antibacterial capability. The quinone groups formed by Fe³⁺ oxidation and protonated amino groups of chitosan polymer further enhance antibacterial property of the hydrogels. Serving as one of the two types of crosslinking mechanisms, the catechol‐Fe³⁺ chelation can covalently link with amino, thiol, and imidazole groups, which substantially enhance the hydrogel's adhesion to biological tissues. The hydrogel's adhesion to porcine skin shows a lap shear strength of 18.1 kPa, which is 6‐time that of the clinically established Fibrin Glue's adhesion. The hydrogel also has a good hemostatic performance due to the superior tissue adhesion as demonstrated with a hemorrhaging liver model. Furthermore, the hydrogel can remarkably promote healing of bacteria‐infected wound.     

Phototunable Underwater Oil Adhesion of Micro/Nanoscale Hierarchical‐Structured ZnO Mesh Films with Switchable Contact Mode

Controllable surface adhesion of solid substrates has aroused great interest both in air and underwater in solving many challenging interfacial science problems such as robust antifouling, oil‐repellent, and highly efficient oil/water separation materials. Recently, responsive surface adhesion, especially switchable adhesion, under external stimulus in air has been paid more and more attention in fundamental research and industrial applications. However, phototunable underwater oil adhesion is still a challenge. Here, an approach to realize phototunable underwater oil adhesion on aligned ZnO nanorod array‐coated films is reported, via a special switchable contact mode between an unstable liquid/gas/solid tri‐phase contact mode and stable liquid/liquid/solid tri‐phase contact mode. The photo‐induced wettability transition to water and air exists (or does not) in the micro/nanoscale hierarchical structure of the mesh films, playing important role in controlling the underwater oil adhesion behavior. This work is promising in the design of novel interfacial materials and functional devices for practical applications such as photo‐induced underwater oil manipulation and release, with loss‐free oil droplet transportation.     

Bioinspired Adhesive Hydrogels Tackified by Nucleobases

Bioinspired strategies for designing hydrogels with excellent adhesive performance have drawn much attention in biomedical applications. Here, bioinspired adhesive hydrogels tackified by independent nucleobase (adenine, thymine, guanine, cytosine, and uracil) from DNA and RNA are successfully explored. The nucleobase‐tackified hydrogels exhibit an excellent adhesive behavior for not only various solid substrates (polytetrafluoroethylene, plastics, rubbers, glasses, metals, and woods) but also biological tissues consisting of heart, liver, spleen, lung, kidney, bone, and muscle. The maximum adhesion strength of A‐, T‐, G‐, C‐, and U‐tackified hydrogels on the aluminum alloy surface is 780, 166, 250, 227, and 433 N m^?1, respectively, superior to that of pure PAAm hydrogels (40 N m^?1) after adhesive time of 10 min. It is anticipated that bioinspired hydrogels will play a significant role in the applications of wound dressing, medical electrodes, tissue adhesives, and portable equipment. Moreover, the bioinspired nucleobase‐tackified strategy would open a novel avenue for designing the next generation of soft and adhesive materials.     

Wet‐Responsive,Reconfigurable, and Biocompatible Hydrogel Adhesive Films for Transfer Printing of Nanomembranes

This study presents a wet‐responsive and biocompatible smart hydrogel adhesive that exhibits switchable and controllable adhesions on demand for the simple and efficient transfer printing of nanomembranes. The prepared hydrogel adhesives show adhesion strength as high as ≈191 kPa with the aid of nano‐ or microstructure arrays on the surface in the dry state. When in contact with water, the nano/microscopic and macroscopic shape reconfigurations of the hydrogel adhesive occur, which turns off the adhesion (≈0.30 kPa) with an extremely high adhesion switching ratio (>640). The superior adhesion behaviors of the hydrogels are maintained over repeating cycles of hydration and dehydration, indicating their ability to be used repeatedly. The adhesives are made of a biocompatible hydrogel and their adhesion on/off can be controlled with water, making the adhesives compatible with various materials and surfaces, including biological substrates. Based on these smart adhesion capabilities, diverse metallic and semiconducting nanomembranes can be transferred from donor substrates to either rigid or flexible surfaces including biological tissues in a reproducible and robust fashion. Transfer printing of a nanoscale crack sensor onto a bovine eye further demonstrates the potential of the reconfigurable hydrogel adhesive for use as a stimuli‐responsive, smart, and versatile functional adhesive for nanotransfer printing.     

Self-Contained Underwater Adhesion and Informational Labeling Enabled by Arene-Functionalized Polymeric Ionogels

Adhesives and water exhibit a conflicting correlation as indicated by the failure of most synthetic adhesives in submerged and humid environments. Development of instant, strong, reversible, and long-lasting adhesives that can adhere to wet surfaces and function in underwater environments presents a formidable challenge, yet it is of paramount importance in biomedical and engineering applications. Herein, viscoelastic and moldable ionogels are developed based on synergistic engineering of aromatic substituents, fluorinated counterions, ionic building blocks, and 3D cross-linked networks. The molecular design and structural engineering result in a facile synthesis, two bonding methods (glue- and tape-type), and the combined mechanisms of enhanced adhesion and cohesion. The high underwater adhesion strength of over 8.9 MPa is among the best-performing tape-type underwater adhesives reported to date. A combination of excellent durability, reliability, deformation resistance, salt tolerance, water proof, antiswelling, and self-healing properties demonstrates the “self-contained” underwater adhesion. Furthermore, the extended π-conjugation of the aromatic pendant groups confers a new functionality to the ionogels – visible fluorescence, enabling intriguing applications such as underwater labeling, information encryption, and signal transmission. This study shines lights on the fabrication of ionogel-based adhesives and provides their future perspectives in underwater sealing, self-repair, crack diagnosis, and informational labeling.     

Super Bulk and Interfacial Toughness of Physically Crosslinked Double‐Network Hydrogels

Conventional design wisdom prevents both bulk and interfacial toughness to be presented in the same hydrogel, because the bulk properties of hydrogels are usually different from the interfacial properties of the same hydrogels on solid surfaces. Here, a fully‐physically‐linked agar (the first network)/poly(N ‐hydroxyethyl acrylamide) (pHEAA, the second network), where both networks are physically crosslinked via hydrogen bonds, is designed and synthesized. Bulk agar/pHEAA hydrogels exhibit high mechanical properties (2.6 MPa tensile stress, 8.0 tensile strain, 8000 J m^?2 tearing energy, 1.62 MJ m^?3 energy dissipation), high self‐recovery without any external stimuli (62%/30% toughness/stiffness recovery), and self‐healing property. More impressively, without any surface modification, agar/pHEAA hydrogels can be easily and physically anchored onto different nonporous solid substrates of glass, titanium, aluminum, and ceramics to produce superadhesive hydrogel–solid interfaces (i.e., high interfacial toughness of 2000–7000 J m^?2). Comparison of as‐prepared and swollen gels in water and hydrogen‐bond‐breaking solvents reveals that strong bulk toughness provides a structural basis for strong interfacial toughness, and both high toughness mainly stem from cooperative hydrogen bonds between and within two networks and between two networks and solid substrates. This work demonstrates a new gel system to achieve superhigh bulk and interfacial toughness on nonporous solid surfaces.     

Highly Elastic Micropatterned Hydrogel for Engineering Functional Cardiac Tissue

Heart failure is a major international health issue. Myocardial mass loss and lack of contractility are precursors to heart failure. Surgical demand for effective myocardial repair is tempered by a paucity of appropriate biological materials. These materials should conveniently replicate natural human tissue components, convey persistent elasticity, promote cell attachment, growth and conformability to direct cell orientation and functional performance. Here, microfabrication techniques are applied to recombinant human tropoelastin, the resilience‐imparting protein found in all elastic human tissues, to generate photocrosslinked biological materials containing well‐defined micropatterns. These highly elastic substrates are then used to engineer biomimetic cardiac tissue constructs. The micropatterned hydrogels, produced through photocrosslinking of methacrylated tropoelastin (MeTro), promote the attachment, spreading, alignment, function, and intercellular communication of cardiomyocytes by providing an elastic mechanical support that mimics their dynamic mechanical properties in vivo. The fabricated MeTro hydrogels also support the synchronous beating of cardiomyocytes in response to electrical field stimulation. These novel engineered micropatterned elastic gels are designed to be amenable to 3D modular assembly and establish a versatile, adaptable foundation for the modeling and regeneration of functional cardiac tissue with potential for application to other elastic tissues.     

Bio-Multifunctional Hydrogel Patches for Repairing Full-Thickness Abdominal Wall Defects

Developing bio-multifunctional patches with natural extracellular matrix-like structures, excellent high adhesion in the wet state, self-healing ability, antibacterial activity, and favorable cell responses for accelerating tissue healing is highly desirable in clinical applications. Herein, bio-multifunctional composite hydrogels are developed by coupling carboxymethyl chitosan and 4-arm poly (ethylene glycol) aldehyde for full-thickness abdominal wall defect repair. The prepared hydrogels exhibit excellent self-healing and mechanical properties, high adhesion in the wet state, and significant antibacterial ability. In vitro cellular experiments show that the hydrogels combined with recombinant bovine basic fibroblast growth factor remarkably promote cell proliferation and then accelerate full-thickness abdominal wall defect repair in a rat model. The histomorphological evaluation shows that compared to the commercial polypropylene mesh used clinically, the designed hydrogel patches facilitate an increase in the thickness and integrity of the abdominal wall tissue by upregulating the production of Ki67, enhancing the formation of collagen, inducing neovascularization, and inhibiting inflammation by reducing the expression of IL-6, TNF-α, and IL-1β. The results demonstrate that this novel bio-multifunctional hydrogel patch holds great potential for the treatment of full-thickness abdominal wall defects.     

Patterned Hydrogels for Controlled Platelet Adhesion from Whole Blood and Plasma

This work describes the preparation and properties of hydrogel surface chemistries enabling controlled and well‐defined cell adhesion. The hydrogels may be prepared directly on plastic substrates, such as polystyrene slides or dishes, using a quick and experimentally simple photopolymerization process, compatible with photolithographic and microfluidic patterning methods. The intended application for these materials is as substrates for diagnostic cell adhesion assays, particularly for the analysis of human platelet function. The non‐specific adsorption of fibrinogen, a platelet adhesion promoting protein, is shown to be completely inhibited by the hydrogel, provided that the film thickness is sufficient (>5 nm). This allows the hydrogel to be used as a matrix for presenting selected bioactive ligands without risking interference from non‐specifically adsorbed platelet adhesion factors, even in undiluted whole blood and blood plasma. This concept is demonstrated by preparing patterns of proteins on hydrogel surfaces, resulting in highly controlled platelet adhesion. Further insights into the protein immobilization and platelet adhesion processes are provided by studies using imaging surface plasmon resonance. The hydrogel surfaces used in this work appear to provide an ideal platform for cell adhesion studies of platelets, and potentially also for other cell types.     

Mussel‐Inspired Hydrogels for Self‐Adhesive Bioelectronics

Wearable and implantable bioelectronics are receiving a great deal of attention because they offer huge promise in personalized healthcare. Currently available bioelectronics generally rely on external aids to form an attachment to the human body, which leads to unstable performance in practical applications. Self‐adhesive bioelectronics are highly desirable for ameliorating these concerns by offering reliable and conformal contact with tissue, and stability and fidelity in the signal detection. However, achieving adequate and long‐term self‐adhesion to soft and wet biological tissues has been a daunting challenge. Recently, mussel‐inspired hydrogels have emerged as promising candidates for the design of self‐adhesive bioelectronics. In addition to self‐adhesiveness, the mussel‐inspired chemistry offers a unique pathway for integrating multiple functional properties to all‐in‐one bioelectronic devices, which have great implications for healthcare applications. In this report, the recent progress in the area of mussel‐inspired self‐adhesive bioelectronics is highlighted by specifically discussing: 1) adhesion mechanism of mussels, 2) mussel‐inspired hydrogels with long‐term and repeatable adhesion, 3) the recent advance in development of hydrogel bioelectronics by reconciling self‐adhesiveness and additional properties including conductivity, toughness, transparency, self‐healing, antibacterial properties, and tolerance to extreme environment, and 4) the challenges and prospects for the future design of the mussel‐inspired self‐adhesive bioelectronics.     

Tissue Engineering: Scaffold‐Mediated 2D Cellular Orientations for Construction of Three Dimensionally Engineered Tissues Composed of Oriented Cells and Extracellular Matrices (Adv. Funct. Mater. 7/2009)

Various hydrogels, such as poly(γ‐glutamic acid) (γ‐PGA), gelatin (GT), alginic acid (Alg), and agarose (Aga), with 3D interconnected and oriented fibrous pores (OP gels) are prepared for 3D polymeric cellular scaffolds by using silica fiber cloth (SC) as template. After the preparation of these hydrogels with the SC templates, the latter are subsequently removed by washing with hydrofluoric acid solution. Scanning electron microscopy (SEM) clearly shows OP structures in the hydrogels. These various types of OP gels are successfully prepared in this way, independently of the crosslinking mechanism, such as chemical (γ‐PGA or GT), coordinate‐bonded (Alg), or hydrogen‐bonded (Aga) crosslinks. SEM, confocal laser scanning microscopy, and histological evaluations clearly demonstrate that mouse L929 fibroblast cells adhere to and extend along these OP structures on/in γ‐PGA hydrogels during 3D cell culture. The L929 cells that adhere on/in the oriented hydrogel are viable and proliferative. Furthermore, 3D engineered tissues, composed of the oriented cells and extracellular matrices (ECM) produced by the cells, are constructed in vitro by subsequent decomposition of the hydrogel with cysteine after 14 days of cell culture. This novel technology to fabricate 3D‐engineered tissues, consisting of oriented cells and ECM, will be useful for tissue engineering.     

Supramolecular β‐Sheet Suckerin–Based Underwater Adhesives

Nature has evolved several molecular strategies to ensure adhesion in aqueous environments, where artificial adhesives typically fail. One recently‐unveiled molecular design for wet‐resistant adhesion is the cohesive cross‐β structure characteristic of amyloids, complementing the well‐established surface‐binding strategy of mussel adhesive proteins based on 3,4‐l ‐dihydroxyphenylalanine (Dopa). Structural proteins that self‐assemble into cross β‐sheet networks are the suckerins discovered in the sucker ring teeth of squids. Here, light is shed on the wet adhesion of cross‐β motifs by producing recombinant suckerin‐12, naturally lacking Dopa, and investigating its wet adhesion properties. Surprisingly, the adhesion forces measured on mica reach 70 mN m^?1, exceeding those measured for all mussel adhesive proteins to date. The pressure‐sensitive adhesion of artificial suckerins is largely governed by their cross‐β motif, as evidenced using control experiments with disrupted cross‐β domains that result in complete loss of adhesion. Dopa is also incorporated in suckerin‐12 using a residue‐specific incorporation strategy that replaces tyrosine with Dopa during expression in Escherichia coli. Although the replacement does not increase the long‐term adhesion, it contributes to the initial rapid contact and enhances the adsorption onto model oxide substrates. The findings suggest that suckerins with supramolecular cross‐β motifs are promising biopolymers for wet‐resistant adhesion.     

Insights into the Adhesive Mechanisms of Tree Frogs using Artificial Mimics

Elastic, microstructured surfaces (hydrophobic and hydrophilic) mimicking the surface structure of tree‐frog toe‐pads are fabricated. Their adhesion and friction behaviour in the presence of a liquid layer is evaluated and compared to flat controls. Tree‐frog‐like patterns are beneficial for wet adhesion only if the liquid does not wet the surface. The situation is different in friction, where the surface structure lead to significantly higher friction forces only if the liquid does wet the surface. Taking into account that tree‐frog attachment pads are hydrophilic and that their secretion wets all kind of surfaces, our results indicate that the surface structure in tree‐frog toe‐pads has been developed for climbing, when shear (friction) forces are involved. These results evidence the benefits and limitations of the surface design (microstructure and hydrophilicity) for adhesion and friction under wet conditions.     

Microfluidic Spinning of Cell‐Responsive Grooved Microfibers

Engineering living tissues that simulate their natural counterparts is a dynamic area of research. Among the various models of biological tissues being developed, fiber‐shaped cellular architectures, which can be used as artificial blood vessels or muscle fibers, have drawn particular attention. However, the fabrication of continuous microfiber substrates for culturing cells is still limited to a restricted number of polymers (e.g., alginate) having easy processability but poor cell–material interaction properties. Moreover, the typical smooth surface of a synthetic fiber does not replicate the micro‐ and nanofeatures observed in vivo, which guide and regulate cell behavior. In this study, a method to fabricate photocrosslinkable cell‐responsive methacrylamide‐modified gelatin (GelMA) fibers with exquisite microstructured surfaces by using a microfluidic device is developed. These hydrogel fibers with microgrooved surfaces efficiently promote cell encapsulation and adhesion. GelMA fibers significantly promote the viability of cells encapsulated in/or grown on the fibers compared with similar grooved alginate fibers used as controls. Importantly, the grooves engraved on the GelMA fibers induce cell alignment. Furthermore, the GelMA fibers exhibit excellent processability and could be wound into various shapes. These microstructured GelMA fibers have great potential as templates for the creation of fiber‐shaped tissues or tissue microstructures.     

Particle Surfaces to Study Macrophage Adherence,Migration, and Clearance

Nanoparticle adsorption to substrates pose a unique challenge to understand uptake mechanisms as it involves the organization of complex cytoskeletal components by cells to perform endocytosis/phagocytosis. In particular, it is not well‐understood from a cell mechanics perspective how the adhesion of particles on substrate will influence the ease of material clearance. By using a particle model, key contributing factors underlying cell adhesion on nonporous silica particle surfaces, migration and engulfment, are simulated and studied. Following a 24 h incubation period, monocyte‐derived macrophages and A549 epithelial cells are able to adhere and remove particles in their local vicinity through induction of adhesive pulling arise from cell traction forces and phagocytic/endocytic mechanisms, in a size‐dependent manner. It is observed that such particle‐decorated surfaces can be used to address the influence of surface topography on cell behavior. Substrates which presented 480 nm silica particles are able to induce greater development and maturation of focal adhesions, which play an important role in cellular mechanoregulation. Moreover, under a chemotactic influence, in the presence of 30% fetal bovine serum, macrophages are able to uptake the particles and be directed to translocate along a concentration gradient, indicating that local mechanical effects do not substantially impair normal physiological functions.     

Adhesion and Surface Interactions of a Self‐Healing Polymer with Multiple Hydrogen‐Bonding Groups

The surface properties and self‐adhesion mechanism of self‐healing poly(butyl acrylate) (PBA) copolymers containing comonomers with 2‐ureido‐4[1H]‐pyrimidinone quadruple hydrogen bonding groups (UPy) are investigated using a surface forces apparatus (SFA) coupled with a top‐view optical microscope. The surface energies of PBA–UPy4.0 and PBA–UPy7.2 (with mole percentages of UPy 4.0% and 7.2%, respectively) are estimated to be 45–56 mJ m^?2 under dry condition by contact angle measurements using a three probe liquid method and also by contact and adhesion mechanics tests, as compared to the reported literature value of 31–34 mJ m^?2 for PBA, an increase that is attributed to the strong UPy–UPy H‐bonding interactions. The adhesion strengths of PBA–UPy polymers depend on the UPy content, contact time, temperature and humidity level. Fractured PBA–UPy films can fully recover their self‐adhesion strength to 40, 81, and 100% in 10 s, 3 h, and 50 h, respectively, under almost zero external load. The fracture patterns (i.e., viscous fingers and highly “self‐organized” parallel stripe patterns) have implications for fabricating patterned surfaces in materials science and nanotechnology. These results provide new insights into the fundamental understanding of adhesive mechanisms of multiple hydrogen‐bonding polymers and development of novel self‐healing and stimuli‐responsive materials.