Hydrogel‐based wearable electronic devices have received increasing attention. However, the construction of underwater strain sensors remains a significant challenge because of the swelling of ...hydrogels in an aquatic environment. This work presents the fabrication of an anti‐swellable hydrogel composed of polyvinyl alcohol (PVA), a copolymer of 2‐(methacryloyloxy) ethyldimethyl‐(3‐sulfopropyl) ammonium hydroxide (SBMA) and 2‐hydroxyethyl methacrylate. Interestingly, facile switch of the SBMA moiety from neutral to positively charged status at a low pH value leads to reduced osmotic pressure of the hydrogel for electrostatic repulsion‐driven elimination of water molecules and anti‐swelling. The resulting anti‐swellable hydrogel exhibits high toughness (518 kJ m−3) and compressive modulus (8.12 Mpa), ionic conductivity (up to 4.58 S m−1), and anti‐swelling behavior (equilibrium swelling ratio of 9% in water for 30 days). An underwater strain sensor based on this anti‐swellable hydrogel is further developed to monitor the movements of underwater sports. High sensitivity is achieved to identify multidirectional motions, including raising the head, swinging the arm, bending the elbow, knee and finger. Therefore, this study offers a facile strategy to generate hydrogel‐based sensors that can be adopted in an underwater environment as well as expands the potential applications of wearable electronic devices.
A hydrogel sensor that combines anti‐swelling, mechanical toughness, and ionic conductivity is fabricated by virtue of polyelectrolyte nature, to address the challenge of the swelling of hydrogels in an aquatic environment. Underwater targeted motion detection and sensitive real‐time signals output are achieved. This system has the potential to be used as a wearable electronic device for underwater motion monitoring.
Injectable hydrogel adhesives integrating both rapid adhesion to wet tissues and anti‐swelling in humid environments are highly desired for fast hemostasis and wound sealing in surgical applications. ...Herein, utilizing the synergistic effect of thermo‐sensitive shrinkable nano‐micelle gelators and small molecular adhesive moieties, an injectable hydrogel with rapid‐adhesion and anti‐swelling properties (RAAS hydrogel) is fabricated. The RAAS hydrogel can undergo ultrafast gelation to achieve wet adhesion within 2 s of ultraviolet illumination and exhibit an outstanding anti‐swelling performance with non‐expansion of volume during the whole degradation process. It also presents good biocompatibility and low risk of hemolysis. Its fast hemostasis is demonstrated in diverse hemorrhage models with injuries in the liver, artery, heart, cranial vessel, and brain cortex in small animals. Importantly, its volume stability in humid internal environment can maintain the strong adhesion strength and avoid compression injury to spinal cord when applied for dura sealing. These data suggest that the injectable RAAS hydrogel holds potential for the applications of fast hemostasis and wound sealing with the benefits of stable adhesion and reducing the risk of tissue compression injury.
The hydrogel possessing dual capacities of rapid‐adhesion and anti‐swelling (RAAS hydrogel) is developed based on the synergistic effects of temperature‐sensitive shrinkage of nanomicelle gelator, small molecular adhesive moiety, and rapid photocuring ability. Compared with general swelling adhesive hydrogels, the RAAS hydrogel can avoid compression injury to surrounding tissues, such as the spinal cord, after achieving hemostasis and wound sealing.
•The model links coal matrix swelling, localized swelling, and bulk swelling.•Matrix, local, and bulk swelling strain changes during CO2 injection are given.•Dynamic partial separation coefficients ...deal with local-to-bulk swelling transition.
Injection of CO2 and coal seam gas production induce coal swelling/shrinkage. Laboratory tests indicate that coal swelling may go through several stages from localized swelling at fracture surfaces to bulk rock swelling. The coal Langmuir swelling strain constant normally ranges from 0 to 0.04. This study provides a process-based coal swelling model that covers the whole swelling procedure. We account for three swelling strains, videlicet, the matrix swelling strain, fracture swelling strain, and bulk rock swelling strain. Dynamic partial separation coefficients are employed to quantify the contributions of the matrix swelling strain to bulk swelling and the fracture (cleat) aperture reduction, bridge the gaps between localized swelling and bulk swelling, and link the three types of strains. This model is inserted into a permeability model and verified against permeability measurement and rock swelling data. The three samples used for verification are bituminous coals from the Illinois Basin (depth of ~ 200 m) in the US and Henan Province in China (depth of ~ 310 m). In essence, the swelling model is also applicable to other coal types with a linear relationship between the matrix swelling strain and adsorbed gas content. By matching with long-term permeability measurement data, multiple permeability evolution stages are observed due to the swelling transition. Sensitivity analyses show that the matrix block size, matrix swelling properties, and diffusivity control the duration, occurrence, and magnitude of matrix swelling’s contribution to local and bulk swelling during swelling transition, while rock bridge swelling properties have a marginal influence on coal swelling.
Swelling is ubiquitous for conventional hydrogels but is not favorable for many situations, especially underwater applications. In this study, an anti‐swelling and mechanically robust polyacrylic ...acid (PAAc)/gelatin composite hydrogel is reported with a rapid gelation process (101 s) under mild conditions via the synergy of MXene‐activated initiation and zirconium ion (Zr4+)‐induced cross‐linking, without the requirement of external energy input. The MXene is found efficient to activate the chain initiation, while the Zr4+ is prone indispensable for facilitating the cross‐linking of formed polymer chains. The resulting hydrogel exhibits integration of exceptional anti‐swelling properties and high mechanical performance at room temperature, thanks to the dense hydrogen bonds between PAAc and gelatin chains that enable an upper critical solution temperature above room temperature. Also, desirable electrical conductivity emerges in the hydrogel due to the simultaneous contribution of MXene and Zr4+, allowing stable electrical signal output of the gel upon deformation underwater. As a demonstration, an underwater communicator by harnessing the gel as a sensing module is assembled, which is capable of wirelessly delivering messages to the decoder on the ground via Morse codes. This study provides an exemplary way for the rapid gelation of tough and anti‐swelling hydrogels for durable underwater applications.
Rapid gelation of tough and anti‐swelling hydrogels under mild conditions is enabled by the synergistic effect of MXene and zirconium ions, without requiring external energy input. The MXene facilitates the chain initiation, while the zirconium ions cross‐link the formed polymer chains. The resulting hydrogels exhibit an upper critical solution temperature behavior to resist swelling at room temperature, promising their applications in underwater communication.
Due to the wet and dynamic environment of the oral cavity, the healing of intraoral wounds, such as tooth extraction wounds, requires stable and firm wound dressings. In clinical practice, cotton ...balls and gauzes, sponge plugs, or sutures are used to treat extraction wounds, but none of these means can continuously isolate the wound from the intraoral environment and facilitate ideal healing conditions. Herein, inspired by the natural extracellular matrix, a family of wound dressings is developed for intraoral wound repair. Infiltrating a ductile long‐chain hydrogel network into a prefabricated, sturdy macromolecular meshwork and in situ crosslinking endowed the composite hydrogel with controllable swelling behaviors and robust mechanical properties. The macromolecular meshwork functioned as the backbone to support the composite and restricts the swelling of the long‐chain hydrogel network. In vitro tests verified that this wound dressing can provide durable protection for intraoral wounds against complex irritations. Furthermore, accelerated wound healing occurred when the wound dressing is applied in vivo on a canine tooth extraction model, due to the effective reduction of acute inflammation. These results suggest that this family of bioinspired hydrogels has great potential for application as intraoral wound dressing.
An extracellular matrix‐mimicking hydrogel wound dressing is designed as tooth extraction adhesive wound dressing for intraoral application. The hydrogel exhibits excellent anti‐swelling efficiency, along with consistent mechanical and adhesive robustness in aqueous environments. In vitro and in vivo tooth extraction models demonstrate the stability of hydrogels as physical and antibacterial barriers for intraoral wounds, leading to continuous protection and effective healing acceleration.
Ti3C2Tx (MXene) displays prominent properties in water purification due to its rich surface chemistry and physicochemical property. However, the separation property is severely restrained because of ...the intercalation‐induced swelling. Inspired by the column‐to‐beam structure house, an advanced MXene‐based membrane is developed with a stable interlayer spacing for water purification. Laminar Ti3C2Tx nanosheets with numerous nanochannels are set as the “beam” part, and the boron nitride (BN) nanosheets are thought of as the “brick” part of the MXene‐based integrated membrane. Moreover, the Ti3C2Tx nanosheets form stable interactions with the BN nanosheets through covalent cross‐linking and supramolecular hydrogen bonding. Furthermore polydopamine and polyethylenimine assume the roles of the “column” part of this membrane through covalent cross‐linking interaction. Therefore, this membrane shows outstanding anti‐swelling property with a stable interlayer spacing of 14.7 ± 0.13 Å after 600 h immersion in water, which is superior to that of most previously reported works. In addition, its hydrophilic functional groups and charges endow itself with exceptional anti‐fouling ability. This work may offer a promising manner to construct advanced separation materials with a stable structure for precise water purification.
The desigend MXene‐based membrane shows outstanding anti‐swelling property with a stable interlayer spacing of 14.7 ± 0.13 Å after 600 hours immersion in water, superior to most the previous reports. Furthermore, the superhydrophilicity and charges endow itself with an exceptional anti‐fouling ability. This work can offer a promising platform to design novel membranes with stable structure for water purification.
A specific oedometer cell has been set up to measure the swelling pressure of compacted montmorillonites at constant volume and to concomitantly visualise the evolution, upon wetting, of how the ...microstructure is organised through X-ray microtomography. The swelling pressure experiments were conducted with solvents of various natures. In addition to conventionally used water and saline solutions, we used an organic solvent (methyl methacrylate – MMA). We chose this to explore the effect of its different physical and chemical properties, and to differentiate the respective roles of crystalline and osmotic pressures on macroscopic swelling behaviour.
The results, which combined both swelling pressure measurements and quantification of microstructure evolution upon hydration for the two different solutes, give sound understanding on the development of osmotic and/or crystalline swelling and their relative impact both on the microstructure and on the magnitude of the macroscopic swelling pressure of compacted montmorillonites.
•A new oedometer is designed to follow swelling pressure and macropore evolution at the same time by X-ray tomography.•Hydration solutions' features (solute, MMA) influence the macroporosity decrease and swelling behaviour.•Swelling pressure evolution is correlated with macroporosity investigated on the X-ray tomography scale.•Crystalline and osmotic components impact aggregate fabric and modify the mechanical properties of a part of the sample.
Hydrogels with tailor-made swelling-shrinkable properties have aroused considerable interest in numerous biomedical domains. For example, as swelling is a key issue for blood and wound extrudates ...absorption, the transference of nutrients and metabolites, as well as drug diffusion and release, hydrogels with high swelling capacity have been widely applicated in full-thickness skin wound healing and tissue regeneration, and drug delivery. Nevertheless, in the fields of tissue adhesives and internal soft-tissue wound healing, and bioelectronics, non-swelling hydrogels play very important functions owing to their stable macroscopic dimension and physical performance in physiological environment. Moreover, the negative swelling behavior (i.e., shrinkage) of hydrogels can be exploited to drive noninvasive wound closure, and achieve resolution enhancement of hydrogel scaffolds. In addition, it can help push out the entrapped drugs, thus promote drug release. However, there still has not been a general review of the constructions and biomedical applications of hydrogels from the viewpoint of swelling-shrinkable properties. Therefore, this review summarizes the tactics employed so far in tailoring the swelling-shrinkable properties of hydrogels and their biomedical applications. And a relatively comprehensive understanding of the current progress and future challenge of the hydrogels with different swelling-shrinkable features is provided for potential clinical translations.
Laboratory observations have shown that coal permeability under the influence of gas adsorption can change instantaneously from reduction to enhancement. It is commonly believed that this ...instantaneous switching of permeability is due to the fact that the matrix swelling ultimately ceases at higher pressures and the influence of effective stresses take over. In this study, our previously-developed poroelastic model is used to uncover the true reason why coal permeability switches from reduction to enhancement. This goal is achieved through explicit simulations of the dynamic interactions between coal matrix swelling/shrinking and fracture aperture alteration, and translations of these interactions to perrmeability evolution under unconstrained swellings. Our results of this study have revealed the transition of coal matrix swelling from local swelling to macro-swelling as a novel mechanism for this switching. Our specific findings include: (1) at the initial stage of CO
2 injection, matrix swelling is localized within the vicinity of the fracture compartment. As the injection continues, the swelling zone is extending further into the matrix and becomes macro-swelling. Matrix properties control the swelling transition from local swelling to macro swelling; (2) matrix swelling processes control the evolution of coal permeability. When the swelling is localized, coal permeability is controlled by the internal fracture boundary condition and behaves volumetrically; when the swelling becomes macro-swelling, coal permeability is controlled by the external boundary condition and behaves non-volumetrically; and (3) matrix properties control the switch from local swelling to macro swelling and the associated switch in permeability behavior from reduction to recovery. Based on these findings, a permeability switching model has been proposed to represent the evolution of coal permeability under variable stress conditions. This model is verified against our experimental data. It is found that the model predictions are consistent with typical laboratory and in-situ observations available in lietratures.
► We revealed why coal permeability switches from reduction to enhancement under free swelling. ► This switching is due to transition from local swelling to macro-swelling. ► When swelling is localized, coal permeability is controlled by the internal fracture. ► When swelling becomes macro-swelling, permeability is controlled by the external boundary.
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