Three-dimensional Cross-linking Research Articles

Three-Dimensional Cross-Linking Network Coating for the Flame Retardant of Bio-Based Polyamide 56 Fabric by Weak Bonds.

Weak bonds usually make macromolecules stronger; therefore, they are often used to enhance the mechanical strength of polymers. Not enough studies have been reported on the use of weak bonds in flame retardants. A water-soluble polyelectrolyte complex composed of polyethyleneimine (PEI), sodium tripolyphosphate (STPP) and melamine (MEL) was designed and utilized to treat bio-based polyamide 56 (PA56) by a simple three-step process. It was found that weak bonds cross-linked the three compounds to a 3D network structure with MEL on the surface of the coating under mild conditions. The thermal stability and flame retardancy of PA56 fabrics were improved by the controlled coating without losing their mechanical properties. After washing 50 times, PA56 still kept good flame retardancy. The cross-linking network structure of the flame retardant enhanced both the thermal stability and durability of the fabric. STPP acted as a catalyst for the breakage of the PA56 molecular chain, PEI facilitated the char formation and MEL released non-combustible gases. The synergistic effect of all compounds was exploited by using weak bonds. This simple method of developing structures with 3D cross-linking using weak bonds provides a new strategy for the preparation of low-cost and environmentally friendly flame retardants.

3D Hierarchical Ti3C2TX@PANI-Reduced Graphene Oxide Heterostructure Hydrogel Anode and Defective Reduced Graphene Oxide Hydrogel Cathode for High-Performance Zinc Ion Capacitors.

The practical application of supercapacitors (SCs) has been known to be restricted by low energy density, and zinc ion capacitors (ZICs) with a capacitive cathode and a battery-type anode have emerged as a unique technology that can effectively mitigate the issue. To this end, the design of electrodes with low electrochemical impedance, high specific capacitance, and outstanding reaction stability represents a critical first step. Herein, we report the synthesis of hierarchical Ti3C2TX@PANI heterostructures by uniform deposition of conductive polyaniline (PANI) polymer nanofibers on the exposed surface of the Ti3C2TX nanosheets, which are then assembled into a three-dimensional (3D) cross-linking framework by a graphene oxide (GO)-assisted self-convergence hydrothermal strategy. This resulting 3D Ti3C2TX@PANI-reduced graphene oxide (Ti3C2TX@PANI-RGO) heterostructure hydrogel shows a large surface area (488.75 F g-1 at 0.5 A g-1), outstanding electrical conductivity, and fast reaction kinetics, making it a promising electrode material. Separately, defective RGO (DRGO) hydrogels are prepared by a patterning process, and they exhibit a broad and uniform distribution of mesopores, which is conducive to ion transport with an excellent specific capacitance (223.52 F g-1 at 0.5 A g-1). A ZIC is subsequently constructed by utilizing Ti3C2TX@PANI-RGO as the anode and DRGO as the cathode, which displays an extensive operating voltage (0-3.0 V), prominent energy density (1060.96 Wh kg-1 at 761.32 W kg-1, 439.87 Wh kg-1 at 9786.86 W kg-1), and durable cycle stability (retaining 67.9% of the original capacitance after 4000 cycles at 6 A g-1). This study underscores the immense prospect of the Ti3C2TX-based heterostructure hydrogel and DRGO as a feasible anode and cathode for ZICs, respectively.

Effective and eco-friendly safe self-antimildew strategy to simultaneously improve the water resistance and bonding strength of starch-based adhesive

Starch adhesive, as a sustainable biomass-based adhesive, could be used to solve environmental problems from petroleum-derived adhesive. But its application is hindered by poor water resistance, mildew resistance, and storage stability. Here, a fully bio-based citric acid-starch adhesive (CASt) with high properties was successfully introduced by a simple method. Liquid chromatography/mass spectrometry (LC-MS), and Fourier Transform Infrared spectroscopy (FT-IR) determined that esterification of citric acid (CA) and starch (St) occurred to form a stable three-dimensional crosslinking structure, which strengthened water resistance and bonding strength of the starch adhesive. Compared with native starch (100 %), the soluble content of cured CASt was 1–16 %. CASt adhesive has well storage stability and high mildew resistance. Even after being stored for 5 months, the CASt-1 adhesive (mass ratio of CA/St = 1:1, and reaction time = 1 h) still have good liquidity. And its hot water strength (1.05 ± 0.22 MPa) also satisfied the standard requirements (≥0.7 MPa). The exhibited CASt adhesive is eco-friendly with components from plant resources, which performed as a bright alternative that can substitute petroleum-based adhesives in the artificial board industry.

Novel design and fabrication of form-stable cellulose nanofiber-based phase change composites via click chemistry, coordination reaction, and solvent exchange

Phase change materials (PCMs) show great promise for thermal energy storage and management owing to their high storage capability and stable working temperature. Developing form-stable phase change composites (PCCs) is an effective approach to addressing the liquid leakage problem. However, conventional fabrication methods of incorporating PCMs into three-dimensional crosslinking networks generally involve freeze-drying and vacuum impregnation, which leads to high energy consumption and complicated procedure. Here, we design a novel strategy to rapidly synthesize form-stable PCCs supported by a cellulose nanofiber (CNF)-based skeleton, which combines a series of reactions and methods including click chemistry, coordination reactions, and solvent exchange. The synthesis mechanisms are revealed by adequate characterizations. Based on the facile fabrication strategy, excellent comprehensive performance such as desirable phase change enthalpy, high enthalpy efficiency, superb mechanical and thermal stability, outstanding cycle stability, and mitigated supercooling is realized. Besides, we discover that introducing expanded graphite into the CNF-based matrix could extend the applicability of the strategy from hydrophilic PCMs to hydrophobic PCMs due to repulsion mitigation between the matrix and PCMs, and considerably enhance the thermal conductivity of the PCCs simultaneously. This work achieves a breakthrough in rapidly and effectively fabricating high-performance form-stable PCCs.

Highly Ionic Conductive and Degradable Solid Electrolyte Enabled by a Three-Dimensional Cross-Linking Copolymeric Structure

High ionic conductivity is an essential prerequisite for the application of solid electrolyte (SE) oriented toward solid-state lithium battery (SSLB). Meanwhile, sustainability and environment friendliness of solid electrolytes are required from the green chemistry perspective. However, research on solid electrolytes with simultaneously high ionic conductivity and good degradability remains in its infancy. Herein, a degradable network copolymer solid electrolyte (DNCPSE) was designed and prepared for simultaneously realizing fast lithium-ion transport with a high ionic conductivity of 7.5 × 10–4 S cm–1 at room temperature and fast degradable properties (e.g., completely degraded within 1.5 h in alkaline condition). Experimental characterizations have demonstrated that the construction of a copolymeric network with sufficient polar groups not only boosts fast lithium-ion hopping but also facilitates the whole decomposition of DNCPSE. By virtue of the combined features, this DNCPSE presents remarkable degradable and electrochemical performances. As a result, the DNCPSE-based Li symmetrical cells display high stability (e.g., >1200 h at 0.1 mA cm–2). Moreover, the Li|DNCPSE|LiFePO4 full cells also display impressive cycling performance (e.g., >200 cycles at 1C). This work provides a promising designed rationale and strategy for sustainable solid electrolytes toward green and efficient solid-state lithium battery.

Integrated design of multifunctional all-in-one polymer electrolyte membranes with 3D crosslinking networks toward high-performance lithium metal batteries

Gel polymer electrolytes (GPEs) are highly worthwhile for constructing high-energy-density lithium metal batteries (LMBs) because of their good flexibility and manufacturability. But, it is still challenging to prepare GPEs with excellent electrochemical performance, good flame retardancy, and good compatibility with electrodes for safe and dendrite-free LMBs application. Herein, a well-designed GPE with three-dimensional (3D) crosslinking network containing –CN and -PO(OC2H5)2 functional groups (3D-ADCL) with synergistic effect is prepared via thermal-initiated in-situ polymerization. Concretely, the -PO(OC2H5)2 segment enhances the flame resistance of polymer electrolyte, and the –CN segment grants improved Li-ion conductivity. In addition, the 3D crosslinking networks in the whole LMBs are incredibly favorable for improving the physical stability of both polymer electrolyte membrane/electrode bulks and electrolyte/electrode interface. Furthermore, the 3D-ADCL-based polymer electrolyte (3D-ADCL-PE) demonstrates an enhanced Li-ion transference number (tLi+) of 0.58 because the –CN groups possess strong coordination with Li-ion and electrostatic repulsion with PF6− anion. It is also confirmed that the –CN group can enable the formation of stable Li3N-rich solid electrolyte interphase (SEI) and high-quality cathode electrolyte interphase (CEI) layers to inhibit Li dendrite growth and stabilize the LiFePO4 cathode, respectively. Consequently, the 3D-ADCL-PE based LiFePO4/Li cells exhibit a remarkable capacity of 106.4 mA h g−1 at 6 C-rate with a high capacity retention of 90.3% after long 1000 cycles.

Metal Coordinated Polymer as Three-Dimensional Network Binder for High Sulfur Loading Cathode of Lithium-Sulfur Battery.

The construction of high sulfur (S) loading cathode is one of the critical parameters to obtain lithium-sulfur (Li-S) batteries with high energy density, but the slow redox reaction rate of high S loading cathode limits the development process. In this paper, a metal coordinated polymer-based three-dimensional network binder, which can improve the reaction rate and stability of S electrode. Compared with traditional linear polymer binders, the metal coordinated polymer binder can not only increase the load amount of S through the three-dimensional cross-linking, but also promote the interconversion reactions between S and lithium sulfide (Li2 S), avoiding the passivation of electrode and improving the stability of the positive electrode. At an S load of 4-5mg cm-2 and an E/S ratio of 5.5µL mg-1 , the discharged voltage in the second platform is 2.04V and the initial capacity is 938 mA h g-1 with metal coordinated polymer binder. Moreover, the capacity retention rate approaches 87% after 100 cycles. In comparison, the discharged voltage in the second platform is lost and the initial capacity is 347 mA h g-1 with PVDF binder. It demonstrates the advanced properties of metal-coordinated polymer binders for improving the performance of Li-S batteries.

Biodegradation of vulcanized rubber by a gut bacterium from plastic-eating mealworms

The disposal of vulcanized rubber waste is difficult due to the presence of three-dimensional crosslinking network structure. Here, we report that a bacterium Acinetobacter sp. BIT-H3, isolated from the gut of plastic-eating mealworm, can grow on and degrade vulcanized poly(cis-1,4-isoprene) rubber (vPR). Scanning electronic microscopy (SEM) shows that strain BIT-H3 can penetrate into the vPR and produce craters and cracks. The tensile strength and the crosslink density of vPR decreased by 53.2% and 29.3% after ten weeks’ incubation, respectively. The results of Horikx analysis, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and X-ray absorption near-edge structure (XANES) spectroscopy reveal that strain BIT-H3 can break down both sulfide bridges and double bonds of polymeric backbone within vPR. Sulfate and oligo(cis-1,4 isoprene) with terminal aldehyde and keto groups were identified as metabolic products released during vPR degradation. Through genomic and transcriptional analyses, five enzymes of dszA, dszC1, dszC2, Laccase2147, and Peroxidase1232 were found to be responsible for vPR degradation. Based on the chemical structure characterizations and molecular analyses, a vPR biodegradation pathway was proposed for strain BIT-H3. These findings pave a way for exploiting vulcanized rubber-degrading microorganisms from insect gut and contribute to establish a biodegradation method for vulcanized rubber waste disposal.

Comparative assessment of modified bentonites as retardation barrier: adsorption performance and characterization

Modified bentonites for the anti-seepage system have been attracting global attention. At the same time, the performances of modified bentonite containing retardation barrier exposed to organic–heavy metal pollutants have not been fully reported. In this study, the adsorption performances (one of the key evaluation indicators of retardation barrier) of nine kinds of commonly used modified bentonites on multiple contaminants were comparatively investigated. The x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses were also performed to unravel the adsorption mechanisms. Results show that the adsorption of modified bentonites on phenol and Pb(II) follows the order of SB-16 > PVA > CTAB > APAM > CTAB + PAC > PAC > CPAM > CTAB + PAC > CTAB + CPAM + APAM. Among all the samples, the bentonite modified with SB-16 showed the highest adsorption capacities for phenol and Pb(II). The surfactant molecules inserted in the interlayer space of montmorillonite increase the substrate spacing, which changes the structural properties of the bentonite from hydrophilic to hydrophobic and increases the adsorption of organic contaminants. On the other hand, the polymer has functional groups such as hydroxyl and carboxyl that can form a spatial three-dimensional cross-linking structure on the bentonite surface, providing more adsorption sites for heavy metal ions. These findings indicate the potential industrial applications of modified bentonite in a contaminant barrier system.

Hyperbranched Polymer Network Based on Electrostatic Interaction for Anodes in Lithium-Ion Batteries.

Silicon is considered as one of the ideal anode materials for the new generation of lithium-ion batteries due to its extremely high theoretical specific capacity. Nevertheless, in the actual charging and discharging process, the Si electrode will lose its electrochemical performance due to the huge volume change of Si nanoparticles resulting in detachment from the surface of the fluid collector. The polymer binder can bond the Si nanoparticles together in a three-dimensional cross-linking network, which can thus effectively prevent the Si nanoparticles from falling off the surface of the fluid collector due to the drastic change of volume during the charging and discharging process. Therefore, this study developed a new polymer binder based on electrostatic interaction with hyperbranched polyethylenimine (HPEI) as the main body and water-soluble carboxylated polyethylene glycol (CPEG) as the cross-linker, where the degree of cross-linking can be easily optimized by adjusting the pH value. The results demonstrate that, when the density of positive and negative charges in the binder is relatively balanced at pH 7, the stability of the battery's charge-discharge cycle is significantly improved. After 200 cycles of constant current charge-discharge test, the specific capacity retention rate is 63.3%.

A layered superhydrophobic coating with excellent mechanical robustness and anti-corrosion performances

Lotus-like superhydrophobic coatings play an essential role for the corrosion protection of steel substrates exposed to harsh environments. Thus, improving the mechanical robustness and corrosion resistance of superhydrophobic coatings through macroscopic material matching and microscopic structure manipulation is an important task. In this study, a layered superhydrophobic coating with a “1 + 1” structural mode was successfully prepared using the spinning and spraying techniques. In order to prevent the interface debonding of upper and lower layers, the epoxy resin was introduced as bonding transition zones, and its three-dimensional cross-linking characteristic was used to realize the super stable “welding”. Then, the structure-function design, surface wetting behavior, mechanical robustness and corrosion resistance were systematically investigated. The results showed that the superhydrophobic coating was successfully constructed by designing micro-/nano-scale hierarchical structure and reducing surface energy, achieving a desirable static contact angle of 172.5° and a roll-off angle of 3.4°. Through high-pressure water anti-jetting, high-height sand impacting, and loaded sandpaper shear abrasion tests, the as-prepared coating still showed obvious superhydrophobicity and the shapes of water droplets on the coating surface continued to be nearly spherical. After immersion in 5 wt% NaCl solution for 28 days, an increase of polarization current density was negligible (∼0.0035 μA/cm2), and the impedance values (107 Ω•cm2) of the superhydrophobic coating were approximately three orders of magnitude higher than the control coating in the low-frequency region. This was because the corrosive species (H2O and Cl−) were restricted from entering the coating interior owing to the extreme water-repellence. In addition, the electron-carrying capacity of the superhydrophobic coating was vastly weakened, which impeded the formation of the corrosive conductive circuit and improved the anti-corrosion properties, prolonging the service life of the polymer coating system.

In-situ construction of high-temperature-resistant 3D composite polymer electrolyte membranes towards high-performance all-solid-state lithium metal batteries

Enabling solid polymer electrolytes (SPEs) with enhanced electrochemical properties and high-temperature-resistance is highly desirable for developing high-performance lithium metal batteries (LMBs) with high-safety. In this contribution, single-ion conducting polymers and SiO2 particles, as advanced fillers, are in-situ cross-linked in poly(ethylene oxide) (PEO) based SPEs to form three-dimensional (3D) cross-linking inorganic/organic composite SPEs. Benefiting from the hydrogen bond interaction between the additives and PEO chains, the crystallinity of PEO polymers in the resultant SPEs is greatly decreased, giving rise to high conductivity (3.3 × 10−4 S cm−1) and lithium ion transference number (0.60) at 60 °C. The Li/Li symmetrical cells with the composite SPEs can be run stably more than 400 h at 60 °C and 550 h at 120 °C under 0.1 mA cm−2, respectively. Remarkably, the favorable thermal stability of composite SPEs leads to safer solid-state LMBs operating at the high temperature up to 120 °C, where it reaches an outstanding rate performance up to 4C and displays impressive cycling performances with 89.9% retention over 110 cycles at 1C. This work offers tremendous potential in the practical application of dendrite-free and high-performance LMBs.

Total synthesis of merodesmosine

Elastin is an important extracellular matrix protein responsible for the elasticity of tissues such as ligamentum, arteries, and lungs. Its three-dimensional crosslinking structure plays an important role in its elasticity. However, the precise structure has not yet been clarified since it is difficult to analyze due to its insoluble nature. Merodesmosine is one of the possible crosslinking amino acids in elastin. In this work, the first total synthesis of merodesmosine was achieved in five steps in 21% overall yield from protected allysine. This achievement will aid in the elucidation of the crosslinking structure of elastin.

Double-functional 3D cross-linking carbon fiber with Sn particle coating layer for improving interfacial performance of Na-β″-Al2O3 batteries

β″-Al2O3 solid-state electrolyte (BASE) possesses excellent ionic conductivity and stability with metallic sodium (Na) anode, which shows great application potential in solid-state sodium batteries. However, poor contact between Na anode and solid-state electrolyte causes high interfacial resistance and uneven anodic sodium deposition, which degrades the electrochemical performance of the battery and results in safety concerns. Herein, we demonstrate a double-functional layer composed of three-dimensional (3D) cross-linking carbon fiber with tin (Sn) particle (SC) coating on the BASE surface to enhance interfacial wettability and guide the uniform sodium-ion deposition during the cycling. Experimental results show that the assembled Na symmetric cell exhibits low interfacial area specific resistance (ASR) of 6.6 Ω cm2, and shows long-cycling performance for over 3000 h at 0.2 mA cm−2. The critical current density (CCD) reaches up to 1.3 mA cm−2 at 25 ℃. Moreover, with the SC modified layer, quasi-solid-state sodium cell with Na3V2(PO4)3 cathode presents excellent cycling and rate performance..

Ultrahigh cavitation erosion resistant metal-matrix composites with biomimetic hierarchical structure

Cavitation erosion significantly impairs the serviceability of hydroelectric turbines and causes tremendous economic loss. Therefore, the demand for materials with effective resistance to cavitation erosion is imperative. Here, a novel nickel (Ni)-tungsten carbide (WC) composite coating with biomimetic hierarchical structure (BHS) is proposed. The BHS imitates cuttlebone in microscale and abalone nacre in nanoscale . In microscale, a three-dimensional cross-linking eutectic network of Ni-WC sandwiches divides Ni matrix into many small cells, which effectively inhibits crack propagation to an individual cell, controlling the damage caused by cavitation erosion. In nanoscale, numerical modelling results further reveal that the Ni-WC sandwiches can reduce the tensile stress triggered by cavitation impact and dissipate the impact energy, giving rise to ultrahigh cavitation erosion resistance behaviour. The design of similar structures may promote the development of other metal-matrix composites, establishing new methods for developing material systems with advanced properties. • A novel nickel-tungsten carbide composite with biomimetic hierarchical structure (BHS) is proposed. • The composite with BHS exhibits ultrahigh cavitation erosion resistance. • The designed BHS can inhibit crack growth effectively. • Numerical modelling reveals that the BHS can effectively reduce the tensile stress and dissipate the impact energy.

Preparation of multiple-reactive-site and flexible crosslinking agent with transaconitic acid and acrylic acid and its application for three-dimensional crosslinking of cellulose

A novel multiple-reactive-site crosslinking agent, P(TAA‒AA), was developed from transaconitic acid and acrylic acid in this study. Cotton fabrics with durable wrinkle-resistant properties were obtained by crosslinking with P(TAA‒AA), which benefited from the multifunctional carboxyl groups of crosslinking agents and the three-dimensional crosslinking inside cotton fibers. The wrinkle-resistant properties of P(TAA‒AA)-modified fabrics were evaluated and compared with those of other polycarboxylic acid-treated fabrics, and the P(TAA‒AA)-modified fabrics showed a wrinkle recovery angle of 262° as high as the 1,2,3,4-butanetetracarboxylic acid-modified fabrics while maintaining nearly two-fold higher tearing strength retention (62.9%), and they showed a much higher value of whiteness index than the citric acid-modified fabrics. This demonstrated that the obtained P(TAA‒AA) is an ideal polycarboxylic acid already known to date simultaneously to realize the high wrinkle recovery angle and high tearing strength retention for treated cotton fabrics. The Raman depth mapping images and the scanning electron microscope images of P(TAA‒AA)-modified samples indicated that P(TAA‒AA) molecules can diffuse into the amorphous regions of the cellulose fibers and form crosslinking bridges between cellulose chains. The multiple reactive carboxyl groups in P(TAA‒AA) may form three or more ester bonds between the P(TAA‒AA) molecule and different cellulose chains, which were regarded as the main contribution to the high crosslinking effectiveness of the P(TAA‒AA)-modified fabrics.

Hydrogel Coating with Temperature Response Retention Behavior and Its Application in Selective Separation of Liquid Chromatography

We reporte the double-layer hydrogel-coated mesoporous silica material as a new stationary phase for liquid chromatography. The method of combining physical coating and chemical coating was to apply hydrogel coating on the surface of silica, and finally, a new type of liquid chromatography stationary phase with in situ coating of the functional hydrogel on silica was obtained. This hydrogel-functionalized liquid chromatography stationary phase also exhibits a certain temperature responsiveness. Experimental results show that this temperature response is mainly due to changes in the hydrogen bonding between the stationary phase and the analyte at different temperatures in the column oven, which leads to changes in retention behavior. The hydrogel-coated mesoporous silica microspheres showed excellent selectivity for many polar analytes. An excellent column efficiency was obtained (139 000 plates/m for terephthalic acid) after optimization of chromatographic conditions. In addition to rapid separation of some analytes, this new hydrogel stationary phase also has certain superiority in chromatographic performance compared with other new excellent liquid chromatography stationary phases functioned by three-dimensional cross-linking systems. The important thing is that this strategy is relatively easy to prepare a new stationary phase with different properties.

Degradable photo-crosslinked starch-based films with excellent shape memory property

With the increasingly serious plastic pollution, people's demand for the multi-functional biodegradable plastics is becoming more and more urgent. Inspired by the crosslinked shape memory polymers, the crosslinked starch films were synthesized by inducing the decomposition of benzophenone into free radical and depriving hydrogen on starch macromolecules under UV irradiation, in order to gain a high shape memory performance. The results showed that a three-dimensional crosslinking network between starch macromolecule chains was formed. Compared with the uncrosslinked starch films, the photo-crosslinked films not only had higher mechanical property (tensile strength increased by 154%), but also had better water resistance (water contact angle from 60° to 87°) due to the reduction of free hydroxyl groups. In addition, the stable covalent bonds serving as netpoints endow photo-crosslinked films with great improvement in shape memory property, with nearly 180° bending recovery. More importantly, the maximum shape memory fixity ratio (Rf) and shape memory recovery ratio (Rr) under stretch deformation were 96.5% and 99.8%, respectively. And the Rf and Rr could reach 94.6% and 79.8% even at higher strain. In all, the excellent shape memory performance and good degradability crosslinked starch films, which have great potential application in disposable heat-shrinkable packaging materials.

Diradicals or Zwitterions: The Chemical States of m -Benzoquinone and Structural Variation after Storage of Li Ions

Diradicals or Zwitterions: The Chemical States of <i>m</i> -Benzoquinone and Structural Variation after Storage of Li Ions

Optimizing functional layer of cation exchange membrane by three-dimensional cross-linking quaternization for enhancing monovalent selectivity

Monovalent cation perm-selective membrane (MCPMs) allow fast and selective transport of monovalent cations, and they are promisingly required for extraction of special ions, such as lithium extraction, acid recovery and sea salt production. Herein, we report a novel strategy to design the critical functional layers of MCPMs with both space charge repulsion and cross-linked dense screenability. The in-situ deposition polymerization of pyrrole was carried out on the surface of sulfonated polyphenyl sulfone (SPPSU) substrate membrane followed by cross-linking quaternization of the polypyrrole (PPy) layer with diiodinated functional molecules, thus, the membrane obtained more excellent selective permeability and stable transport properties of monovalent cations. It confirms that the designed PPy layers with charged surface and cross-linking structure improved the hydrophilicity, facilitated cation transport and increased ion flux. Meanwhile, for the dense PPy layer, the charged cross-linked structure endowed the functional layer with the synergistic characteristics of Donnan exclusion and pore size sieving for positively charged ions, which improved the monovalent cation perm-selectivity of the membranes. At a constant current density of 5.1 mA/cm2, the optimal membrane exhibited superior perm-selectivity (PMgNa=2.07) and monovalent cation flux (JNa+ = 2.80 × 10 −8 mol cm−2 s−1) during electrodialysis.