Most gels and elastomers introduce sacrificial bonds in the covalent network to dissipate energy. However, long‐term cyclic loading caused irreversible fatigue damage and crack propagation cannot be ...prevented. Furthermore, because of the irreversible covalent crosslinked networks, it is a huge challenge to implement reversible mechanical interlocking and reorganize the polymer segments to realize the recycling and reuse of ionogels. Here, covalent crosslinking of host materials is replaced with entanglement. The entangled microdomains are used as physical crosslinking while introducing reversible bond interactions. The interpenetrating, entangled, and elastic microdomains of linear segments and covalent‐network microspheres provide mechanical stability, eliminate stress concentration at the crack tip under load, and achieve unprecedented tear and fatigue resistance of ionogels in any load direction. Moreover, reversible entanglements and noncovalent interactions can be disentangled and recombined to achieve recycling and mechanical regeneration, and the recyclability of covalent‐network microdomains is realized.
Irreversible covalent crosslinking in the matrix polymer network is avoided. The reversible entangled microdomains of the microspheres and linear segments in tough ionogels act as elastic physical crosslinking points to provide mechanical stability, dissipate stress concentration, and prevent crack propagation in any load direction. The entangled networks can be disentangled to restore the damaged mechanical properties and realize recycling.
In this work, a thiol-ene coupling reaction was employed to prepare the semi-interpenetrating polymer network AEMs. The obtained QP-1/2 membrane exhibits high hydroxide conductivity (162.5 mS cm
at ...80 °C) with a relatively lower swelling ratio, demonstrating its mechanical strength of 42 MPa. This membrane is noteworthy for its improved alkaline stability, as the semi-interpenetrating network effectively limits the attack of hydroxide. Even after being treated in 2 M NaOH at 80 °C for 600 h, 82.5% of the hydroxide conductivity is maintained. The H
/O
fuel cell with QP-1/2 membrane displays a peak power density of 521 mW cm
. Alkaline water electrolyzers based on QP-1/2 membrane demonstrated a current density of 1460 mA cm
at a cell voltage of 2.00 V using NiCoFe catalysts in the anode. All the results demonstrate that a semi-interpenetrating structure is a promising way to enhance the mechanical property, ionic conductivity, and alkaline stability of AEMs for the application of alkaline fuel cells and water electrolyzers.
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Recent years, membrane separation technology has attracted significant research attention because of the efficient and environmentally friendly operation. The selection of suitable ...materials to improve the membrane selectivity, permeability and other properties has become a topic of vital research relevance. Two-dimensional (2D) materials, a novel family of multifunctional materials, are widely used in membrane separation due to their unique structure and properties. In this respect, as a novel 2D material, graphitic carbon nitride (g-C3N4) have found specific attention in membrane separation. This study reviews the application of carbon nitride in gas separation membranes, pervaporation membranes, nanofiltration membranes, reverse osmosis membranes, ion exchange membranes and catalytic membranes, along with describing the separation mechanisms.
Graphitic carbon nitride (g-C
3
N
4
) nanosheets have attracted great attention in the areas of photocatalysis, sensors, energy storages and membrane separations. A three-step exfoliation strategy ...was designed to use solvent exfoliating g-C
3
N
4
nanosheets from bulk g-C
3
N
4
. In the first stage, bulk g-C
3
N
4
was prepared and then exfoliated into g-C
3
N
4
nanosheets by various solvents. In the second stage, molecular dynamics simulations were carried out and the energy barriers for the exfoliations were determined. Various interactions between solvent molecules and exfoliated nanosheet were analyzed. In the third stage, exfoliation was re-carried out according to the result from MD simulation to obtain optimal amount of exfoliated g-C
3
N
4
nanosheets. The experimental result matched with the simulation prediction very well. In combination with simulation and experiment, a successful way to obtain maximum amount of exfoliated g-C
3
N
4
nanosheet was set up. Then a 5.03 mg/mL g-C
3
N
4
suspension was obtained. Meanwhile, a concept of kinetic energy increment was introduced for the first time to explain the exfoliating efficiency of g-C
3
N
4
nanosheets, which greatly reduced the simulation time by 80% compared with the free energies in terms of the potential of mean force.
Electronic skin can detect minute electrical potential changes in the human skin and represent the body's state, which is critical for medical diagnostics and human–computer interface development. On ...the other hand, sweat has a significant effect on the signal stability, comfort, and safety of electronic skin in a real‐world application. In this study, by modifying the cation and anion of a poly(ionic liquid) (PIL) and employing a spinning process, a PIL‐based multilayer nanofiber membrane (PIL membrane) electronic skin with a dual gradient is created. The PIL electronic skin is moisture‐wicking and breathable due to the hydrophilicity and pore size‐gradients. The intrinsically antimicrobial activities of PILs allow the safe collection of bioelectrical signals from the human body, such as electrocardiography (ECG) and electromyography (EMG). In addition, a robotic hand may be operated in real‐time, and a preliminary human–computer interface can be accomplished by simple processing of the collected EMG signal. This study establishes a novel practical approach for monitoring and using bioelectrical signals in real‐world circumstances via the multifunctional electronic skin.
A dual‐gradient poly(ionic liquid) electronic skin with moisture‐wicking, breathable, and antibacterial properties is prepared. Sweat can be delivered to the outside, away from the skin, keeping the electrode‐skin interface dry, ensuring stable and safe collection of bioelectric signals, further enabling real‐time control of a robotic hand. This work provides an unprecedented practical strategy for monitoring and utilization of bioelectrical signals under real conditions.
The mechanical properties of most hydrogels (ionogels) are considerably affected by covalently cross‐linked networks. However, the interactions between solvent/solvent molecules and solvent/polymer ...chains are usually ignored. Herein, a series of ultra‐tough ionogels were prepared via a supramolecular solvent, halometallate ionic liquid, in which cations and coordinating anions form a 3D supramolecular network. The linear polymer chains are physically cross‐linked with supramolecular solvents synergistically enhancing the strength (14.3 MPa), toughness (78 MJ m−3), and Young's modulus (55 MPa) of ionogels, effectively dispersing the stress concentration under load, and obtaining better fatigue resistance and higher fracture energy (198 kJ m−2). Furthermore, the reversible cross‐linking enables green recovery and recycling of ionogels, simply by water. This strategy shows broad applicability based on a variety of supramolecular solvents and coordinatable polymers.
Ultra‐tough and recyclable ionogels are constructed by physical cross‐linking of coordinated supramolecular solvents and linear polymer segments. The solvents in ionogels function as 3D supramolecular networks, which provide strong mechanical support for ionogels.
The performance of alkaline fuel cells is severely limited by substandard anion exchange membranes (AEMs) due to the lower ionic conductivity compared to the proton exchange membranes. The ionic ...conductivity of AEMs can be effectively improved by regulating the microphase structure, but it still cannot meet the practical use requirements. Here, enhanced microphase‐separated structures are constructed by the cooperativity of highly hydrophilic dual cations and highly hydrophobic fluorinated side chains. Meanwhile, the introduction of O enhances the flexibility of side chains and facilitates the formation of ion transport channels. The dual piperidinium cation functionalized membrane (PB2Pip‐5C8F) which is grafted with the ultra‐hydrophobic fluorocarbon chain exhibits a high conductivity of 74.4 mS cm−1 at 30 °C and 168.46 mS cm−1 at 80 °C. Furthermore, the PB2Pip‐5C8F membrane achieves the highest peak power density of 718 mW cm−2 at 80 °C under a current density of 1197 mA cm−2 without back pressure. A long‐term life cell test of this AEM shows a low voltage decay rate of 1.68 mV h−1 over 70 h of operation at 80 °C.
Four types poly(biphenyl piperidinium) membranes are synthesized with fluorocarbon and carbon side chains. The synergistic effects of dual piperidinium cations and fluorocarbon chains are confirmed and the enhanced microphase separation structures are observed, which exhibit high ionic conductivity. The fabricated single cell achieves a peak power density of 718 mW cm−2 at 80 °C without back pressure.
In this study, we developed a superstrong and reversible adhesive, which can possess a high bonding strength in the “adhesive” state and detach with the application of heating. An ionic crystal (IC) ...gel, in which an IC was immobilized within a soft‐polymer matrix, were synthesized via in situ photo‐crosslinking of a precursor solution composed of N, N‐dimethyl acrylamide (DMAA) and a melted IC. The obtained IC gel is homogenous and transparent at melt point. When cooled to the phase transition temperature of the IC, the gel turns into the adhesive with the adhesion strength of 5.82 MPa (on glasses), due to the excellent wetting of melted gel and a thin layer of crystalline IC with high cohesive strength formed on the substrates. The synergistic effects between IC, polymer networks and substrates were investigated by solid state 1H NMR and molecular dynamics simulation. Such an adhesive layer is reversable and can be detached by heating and subsequent re‐adhesion via cooling. This study proposed the new design of removable adhesives, which can be used in dynamic and complex environments.
Inspired by reversible ice adhesion, a reversible ionic crystal (IC) based gel adhesive was prepared, which showed superstrong and reversible adhesion due to the phase transition of ICs. In addition, the reversible adhesion can be adjusted by heating and light, and be effectively monitored by resistance and capacitance.
As a metal-free polymeric photocatalyst, graphitic carbon nitride (g-C3N4) has attracted great attention owing to its high stability and low toxicity. However, g-C3N4 suffers from low light ...harvesting ability which limits its applications in antimicrobial photocatalytic therapy (APCT). Herein, acridinium (ADN)-grafted g-C3N4 (ADN@g-C3N4) nanosheets are prepared via covalent grafting of ADN to g-C3N4. The obtained ADN@g-C3N4 exhibits a narrow optical band gap (2.12 eV) and a wide optical absorption spectrum (intensity a.u. > 0.30) ranging from ultraviolet to near-infrared region. Moreover, ADN@g-C3N4 would produce reactive oxygen species (ROS) under light irradiation to exert effective sterilization and biofilm elimination activities against both gram-negative and gram-positive bacteria. Molecular dynamics simulation reveals that the ADN@g-C3N4 may move toward, tile and insert the bacterial lipid bilayer membrane through strong van der Waals and electrostatic interaction, decreasing the order parameter of the lipid while increasing the conducive of ROS migration, inducing ADN@g-C3N4 with improved antimicrobial and antibiofilm performance. Moreover, ADN@g-C3N4 could efficiently eradicate oral biofilm on artificial teeth surfaces. This work may provide a broad-spectrum light-induced photocatalytic therapy for preventing and treating dental plaque diseases and artificial teeth-related infections, showing potential applications for intractable biofilm treatment applications.
An acridinium-grafted g-C3N4 (ADN@g-C3N4) with a narrow band gap and broad-spectrum light absorption was synthesized. The narrow optical band gap and improved electrostatic interaction with bacterial lipid bilayer membrane of ADN@g-C3N4 strengthened the ROS generation and facilitated the diffusion of ROS to bacteria surface, leading to enhanced photocatalytic and antibacterial activity against bacteria and corresponding biofilm under light irradiation.
An acridinium-grafted g-C3N4 (ADN@g-C3N4) with a narrow band gap and broad-spectrum light absorption was developed as an antimicrobial photocatalytic therapy agent. The ADN@g-C3N4 exhibited enhanced photocatalytic and antibacterial activity against bacteria and corresponding biofilm under light irradiation, showing potential applications for intractable biofilm treatment.
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Carbon dioxide (CO2) as a sustainable comonomer for the synthesis of polycarbonates, polyurea, and polyurethane is attracting continuous interest, whereas the development of multifunctional polymers ...directly from CO2 remains challenging for its inherent inertness. Herein, we report the synthesis and characterization of a recyclable, nonflammable, superstrong, and reversible adhesive via the polycondensation of CO2 and an amino-functionalized ionic liquid. The resulting CO2-sourced ionic polyurea (CIPUa) with commutative urea groups and ionic species in the skeleton shows much higher shear strength on various substrates even below −80 °C than commercial hot-melt adhesives and excellent nonflammability and antibacterial ability than isocyanate-derived nonionic polyurea. CIPUa also demonstrates facile degradation in ZnSO4 aqueous solution and can be recycled into fresh CIPUa. These properties are mainly endowed by the enhanced electrostatic interaction and attenuated hydrogen bonds between the CIPUa chains. This study provides an effective strategy for designing a sustainable CO2-sourced ionic polymer with multiple functions for broad applications.
