Excellent Mechanical Properties Research Articles

Wound Dressing with Electrospun Core-Shell Nanofibers: From Material Selection to Synthesis.

Skin, the largest organ of the human body, accounts for protecting against external injuries and pathogens. Despite possessing inherent self-regeneration capabilities, the repair of skin lesions is a complex and time-consuming process yet vital to preserving its critical physiological functions. The dominant treatment involves the application of a dressing to protect the wound, mitigate the risk of infection, and decrease the likelihood of secondary injuries. Pursuing solutions for accelerating wound healing has resulted in groundbreaking advancements in materials science, from hydrogels and hydrocolloids to foams and micro-/nanofibers. Noting the convenience and flexibility in design, nanofibers merit a high surface-area-to-volume ratio, controlled release of therapeutics, mimicking of the extracellular matrix, and excellent mechanical properties. Core-shell nanofibers bring even further prospects to the realm of wound dressings upon separate compartments with independent functionality, adapted release profiles of bioactive agents, and better moisture management. In this review, we highlight core-shell nanofibers for wound dressing applications featuring a survey on common materials and synthesis methods. Our discussion embodies the wound healing process, optimal wound dressing characteristics, the current organic and inorganic material repertoire for multifunctional core-shell nanofibers, and common techniques to fabricate proper coaxial structures. We also provide an overview of antibacterial nanomaterials with an emphasis on their crystalline structures, properties, and functions. We conclude with an outlook for the potential offered by core-shell nanofibers toward a more advanced design for effective wound healing.

Mechanically rigid metallopeptide nanostructures achieved by highly efficient folding

AbstractNatural proteins must fold into complex three-dimensional structures to achieve excellent mechanical properties vital for biological functions, but this has proven to be exceptionally difficult to control in synthetic systems. As such, the long-standing issue of low mechanical rigidity and stability induced by misfolding constrains the physical and chemical properties of self-assembling peptide materials. Here we introduce a mixed-chirality strategy that enhances folding efficiency in topologically interlocked metallopeptide nanostructures. The orderly entanglement of heterochiral peptide-derived linkers can fold into a compact three-dimensional catenane. These folding-mediated secondary structural changes not only generate biomimetic binding pockets derived from individual peptide strands but also result in strong chiral amplification by the tight interlocking manner. Notably, this strategic ‘chirality mutation’ alters their arrangement into tertiary structures and is pivotal in achieving exceptional mechanical rigidity observed in the metallopeptide crystals, which exhibit a Young’s modulus of 157.6 GPa, approximately tenfold higher than the most rigid proteinaceous materials in nature. This unusual nature is reflected in enhanced peptide-binding properties and heightened antimicrobial activities relative to its unfolded counterpart.

Sustainably sourced and DOPO-derived triols as hardeners for epoxy thermosets: A promising solution to synchronously improve flame retardancy, mechanical strength and toughness

The flammability and brittleness of the diglycidyl ether of bisphenol A (DGEBA)-type epoxy resin greatly restrict its application in electronic appliances and structural materials. However, the synchronous improvement in the flame retardancy, mechanical strength, and toughness of DGEBA-type epoxy thermosets remains a significant challenge. To overcome this challenge, in this study, a sustainably sourced and DOPO-derived triol (DOPO-GL-DCDA) was synthesized from a bio-based material, glycerol 1, 3-diglycerolate diacrylate (GL-DCDA). A series of epoxy thermosets with different phosphorus contents were prepared by introducing DOPO-GL-DCDA into the DGEBA matrix. EP/DOPO-GL-DCDA demonstrated excellent flame retardancy and mechanical properties without compromising transparency. Specifically, EP/DOPO-GL-DCDA-1.0P exhibited a limit oxygen index (LOI) of 34.0 % and a UL-94 V-0 rating, and the total heat release (THR) and peak heat release rate (PHRR) of EP/DOPO-GL-DCDA-1.5P decreased by 36.6 % and 46.8 %, respectively, compared with those of pure EP. In addition, compared with those of pure EP, the tensile strength, impact strength, fracture toughness (KIC), and fracture energy (GIC) of EP/DOPO-GL-DCDA-1.5P increased by 62.8 %, 69.9 %, 62.9 %, and 99.0 %, respectively. Moreover, EP/DOPO-GL-DCDA had better dielectric properties than pure EP. Under the premise of maintaining transparency, this work provided a promising solution to synchronously improve the flame retardancy, mechanical strength, and toughness of epoxy thermosets.

Synthesis and characterization of novel water hyacinth (Eichhornia Crassipes) biodegradable mulch films

In this paper, carboxymethyl cellulose (CMC) and hemicellulose derived from water hyacinth were used to prepare hemicellulose-based biodegradable mulch film by covalent cross-linking and ionic cross-linking in order to expand its application in agricultural production practice. The esterification reaction between hemicellulose, CMC and citric acid resulted in an increase in tensile strength and elongation at break of the membranes. When citric acid was not used as cross-linking agent and the pH was lowered, the sodium carboxylate group was protonated into carboxylic acid group, which provided abundant active sites for chemical cross-linking of hydroxyl group on hemicellulose and hydroxyl group on CMC. Furthermore Zn2+ could cross-link with carboxylic acid group through hydrogen bonding, and when the DS of carboxymethyl group was high, the cross-linking of Zn2+ with Zn2+ was higher, and the conversion into nano ZnO was lower, which was conducive to the uniform distribution and reduction of agglomeration phenomenon in the films. It is favorable for its uniform distribution in the film and reduces the agglomeration phenomenon. The mulch films made from water hyacinth has excellent mechanical properties, light transmittance, water absorption, soil moisture retention and heat preservation, and is biodegradable. This study will provide new ideas for water pollution control and farmland pollution for sustainable agricultural production.

First Principles Calculation of the Effect of Cu Doping on the Mechanical and Thermodynamic Properties of Au-2.0Ni Solder.

To meet the demands for high-temperature performance and lightweight materials in aerospace engineering, the Au-Ni solder is often utilized for joining dissimilar materials, such as Ti3Al-based alloys and Ni-based high-temperature alloys. However, the interaction between Ti and Ni can lead to the formation of brittle phases, like Ti2Ni, TiNi, and TiNi3, which diminish the mechanical properties of the joint and increase the risk of crack formation during the welding process. Cu doping has been shown to enhance the mechanical properties and high-temperature stability of the Au-Ni brazed joint's central area. Due to the difficulty in accurately controlling the solid solution content of Cu in the Au-Ni alloy, along with the high cost of Au, traditional experimental trial-and-error methods are insufficient for the development of Au-based solders. In this study, first principles calculations based on density functional theory were employed to analyze the effect of Cu content on the stability of the Au-2.0Ni-xCu (x = 0, 0.25, 0.5, 0.75, 1.0, 1.25 wt%) alloy phase structure. The thermal properties of the alloy were determined using Gibbs software fitting. The results indicate that the Au-2.0Ni-0.25Cu alloy exhibits the highest plastic toughness (B/G = 5.601, ν = 0.416, Cauchy pressure = 73.676 GPa) and a hardness of 1.17 GPa, which is 80% higher than that of Au-2.0Ni. This alloy balances excellent strength and plastic toughness, meeting the mechanical performance requirements of brazed joints. The constant pressure specific heat capacity (Cp) of the Au-2.0Ni-xCu alloy is higher than that of Au-2.0Ni and increases with Cu content. At 1000 K, the Cp of the Au-2.0Ni-0.25Cu alloy is 35.606 J·mol-1·K-1, which is 5.88% higher than that of Au-2.0Ni. The higher Cp contributes to enhanced high-temperature stability. Moreover, the linear expansion coefficient (CTE) of the Au-2.0Ni-0.25Cu alloy at 1000 K is 8.76 × 10-5·K-1, only 0.68% higher than Au-2.0Ni. The lower CTE helps to reduce the risk of solder damage caused by thermal stress. Therefore, the Au-2.0Ni-0.25Cu alloy is more suitable for brazing applications in high-temperature environments due to its excellent mechanical properties and thermal stability. This study provides a theoretical basis for the performance optimization and engineering application of the Au-2.0Ni-xCu alloy as a gold-based solder.

Oriented Alignment of CsPbBr3 Single-Crystal Arrays for Flexible X-ray Imaging.

The utilization of perovskite materials in flexible optoelectronics is experiencing distinct diversification including X-ray detection applications. Here, we report the oriented alignment of cesium lead bromide (CsPbBr3) single-crystal arrays on flexible polydimethylsiloxane (PDMS) substrates. By precisely confining the crystallization process within spatially delimited precursor droplets, we achieve a well-oriented crystal alignment through the spontaneous rotation of the CsPbBr3 microcuboids. This approach allows for precise control over the microcuboid morphologies by varying the growth temperature. We design flexible X-ray detector arrays by seamlessly integrating CsPbBr3 microcuboids with electrode arrays. The flexible X-ray detector can output a high sensitivity of 1.97 × 105 μC·Gyair-1·cm-2 and a low detection limit of 89 nGyair·s-1 after the surface passivation process. The excellent mechanical properties, outstanding X-ray detection capabilities, and high pixel uniformity are also demonstrated in conformal X-ray imaging of curved surfaces.

Effect of GGBFS on the mechanical properties of metakaolin-based self-compacting geopolymer concrete

The focus of this study is the production and testing of a new self-compacting geopolymer concrete（SCGC）. The concrete has excellent self-compacting properties, mechanical properties and environmental advantages, showing great potential for engineering applications. Due to the high specific surface area of metakaolin (MK), it is challenging to produce a self-compacting geopolymer concrete using metakaolin as the main material. A self-compacting geopolymer concrete with excellent properties was produced by partially replacing metakaolin with ground granulated blast furnace slag (GGBFS). This innovation enriches the diversity of powder material choices for self-compacting geopolymer concrete. The experimental results showed that the addition of ground granulated blast furnace slag significantly enhanced the filling capacity and interstitial passage capacity and wet packing density of ground granulated self-compacting concrete. The best working performance of the concrete was achieved at 40 % GGBFS replacement. The test data were slump extension of 749 mm, T50 time of 3.23 s, V-funnel test time of 8.2 s, L-box test result of 0.96, and wet packing density of 1.946 g/cm3. With the increase in the replacement rate of the ground granulated blast furnace slag, the compressive strength of self-compacting ground polymer concrete and the split tensile strength showed a trend of increasing and then decreasing. The maximum compressive strength of 55.2 MPa and splitting tensile strength of 4.11 MPa were obtained when the substitution rate of ground granulated blast furnace slag was 20 %. The drying shrinkage of self-compacted geopolymer concrete was significantly increased by the addition of excess ground granulated blast furnace slag. The drying shrinkage was increased by 147 % at 40 % substitution rate compared to 0 % substitution rate. Scanning electron microscope (SEM) tests and thermogravimetric analysis were performed on all samples. At ground granulated blast furnace slag substitution rate of 20 %, a uniform and dense gel structure was formed inside. At 40 % ground granulated blast furnace slag substitution rate, the weight loss of the specimens reached 13.4 %, which was 4.22 % more than the control group with 0 % substitution rate. The results showed that GGBFS effectively promoted the generation of internal cementitious structures in SCGC. This study provides the necessary information for the development of metakaolin-based self-compacting geopolymer concrete and contributes to the popularization of metakaolin-based self-compacting geopolymer concrete. It will also broaden the scope of use of metakaolin in self-compacting geopolymer concrete, which will contribute to the diversification of building materials and the development of the construction industry towards a low-carbon and sustainable future.

Hydrogen-Bond-Repairing Solar Evaporator with Reconstructed Large-Width Channels for Durable Solarizing Seawater.

Conventional solarizing seawater suffers from inefficiency and space constraints. Interfacial solar vapor generation (ISVG) presents an energy-efficient alternative, yet the scalability, adaptability, and durability of a solar evaporator for practical use are remaining concerns. Herein, a hydrogen-bond-repairing solar evaporator featuring reconstructed large-width channels is proposed for ongoing solarization of seawater in ISVG. The polyacrylamide/trehalose/graphene hydrogel (PTGH) exhibits excellent mechanical properties and large-width salt discharge channels. PTGH achieves a notable water evaporation rate of 2.82 kg m-2 h-1 under 1 sun and remains effective even in low-temperature environments. The large-area PTGH is able to continuously operate for solarizing seawater under different conditions, until raw brine is highly concentrated, and eventually solid salt is separated from water. Compared to conventional solarizing seawater, PTGH can save 66.67%-75% of time or land to obtain the same amount of solid salt.

Effect of vibration on the interface properties of welded steel joints and filled concrete in steel pipes

Concrete-filled steel tubes (CFSTs) have been increasingly utilized in engineering due to their excellent mechanical properties. Ensuring a solid bond between a steel tube and concrete is essential for optimizing their synergistic effect. This study introduces an internally welded steel bar structure within the inner wall of a steel tube to enhance the bond properties at the connection interface. The influence of various configurations of steel bars welded to the inner surface of the tube on the bond strength is investigated considering the impact of vibration on the load-bearing capacity of the component. This study comprises two groups of specimens, one with vibration and one without vibration, for a total of ten specimens. Each group included CFST members with five distinct internal welded steel bar structures. The experimental results, including load–displacement curves and strain data of the steel tube, were used to assess the impact of the internal welded steel bar configurations on the steel–concrete interface. The sliding process is described by correlating test data with curves and observed phenomena. To comprehensively compare the effects of structural dimensions on the bonding and slipping properties of the welded bars, finite element simulations replicating the experimental conditions were carried out using ABAQUS software, and the simulation results agreed with the experimental observations. The study demonstrated that incorporating internal welded steel bars substantially enhances the bond strength of steel pipe–concrete interfaces. While vibration weakens the bond strength in CFST members, internal welded steel bars mitigate this effect. These findings improve the structural performance of CFST structures and their resilience to external vibrations.

Strong, tough and environment-tolerant organohydrogels for flaw-insensitive strain sensing.

Conductive organohydrogels are promising for strain sensing, while their weak mechanical properties, poor crack propagation resistance and unstable sensing signals during long-term use have seriously limited their applications as high-performance strain sensors. Here, we propose a facile method, i.e., solvent exchange assisted hot-pressing, to prepare strong yet tough, transparent and anti-fatigue ionically conductive organohydrogels (ICOHs). The densified polymeric network and improved crystallinity endow ICOHs with excellent mechanical properties. The tensile strength, toughness, fracture energy and fatigue threshold of ICOHs can reach 36.12 ± 4.15 MPa, 54.57 ± 2.89 MJ m-3, 43.44 ± 8.54 kJ m-2 and 1212.86 ± 57.20 J m-2, respectively, with a satisfactory fracture strain of 266 ± 33%. In addition, ICOH strain sensors with freezing and drying resistance exhibit excellent cycling stability (10 000 cycles). More importantly, the fatigue resistance allows the notched strain sensor to work normally with no crack propagation and output stable and reliable sensing signals. Overall, the unique flaw-insensitive strain sensing makes ICOHs promising in the field of wearable and durable electronics.

Natural Selection on Hydroxyapatite Fiber Orientations for Resisting Damage of Enamel

Teeth have excellent mechanical properties, with high wear resistance and excellent fracture resistance. This is due to their well-organized multilevel hierarchical structure. While a number of studies in the last decades have revealed the relationship between tooth structure and mechanical properties, there is still no general agreement on how different orientations of hydroxyapatite (HAp) fibers affect the mechanical properties of enamel. With a scanning electron microscope and nanoindenter, the orientations of HAp fibers and their properties were investigated. HAp fibers have two different orientations: parallel and perpendicular to the surface. Fibers oriented parallel to the surface exhibited higher hardness, elastic modulus and wear resistance. Under applied force, fibers oriented perpendicular to the surface suffered deeper shearing in the protein along the long axis, resulting in lower mechanical properties. Teeth resist damaging fractures by combining hard and soft structures. This study may lead to new insights into how nature selects for tooth structure and provide a theoretical basis for the bioinspired design.

Numerical analysis of enhanced heat transfer and nanofluid flow mechanisms in fan groove and pyramid truss microchannels

A combined groove and truss structure is designed for rectangular microchannel heat sinks with 4 % Al2O3 nanofluid as the working fluid to address the heat dissipation requirements of high heat flux density electronic devices. The effects of fan shape, elliptical, waterdrop, rectangular, trapezoidal and triangular grooves on the heat transfer characteristics and mechanical properties of microchannels are investigated. The fan-shaped groove microchannels with the best overall heat transfer performance and excellent mechanical properties. The stress of the fan-shaped grooved truss microchannel is reduced by 76.41 % compared to the smooth microchannel. Three structural parameters were investigated, including the length of the truss in the spreading direction (Lx), the ratio of truss flow downstream length to upstream length (e) and truss rod diameter (d). The performance of the microchannels is reflected by the integrated heat transfer factor and the field coordination number. The individual structural parameters were analysed in a single-factor comparison. The microchannels exhibited the best hydrothermal performance in the Reynolds number range of 500 ∼ 1300 at Lx = 0.8 mm, e = 3, d = 0.2 mm. When the Reynolds number is 900, the microchannel with the optimal parameter combination exhibits a remarkable enhancement of 234 % in the Nusselt number and an 80 % increase in the integrated heat transfer factor compared to the rectangular microchannel.

The Influence of Oil and Thermal Aging on the Sealing Characteristics of NBR Seals.

Nitrile Butadiene Rubber (NBR) is widely used as a sealing material due to its excellent mechanical properties and good oil resistance. However, when using NBR material, the seal structure is unable to avoid the negative effects of rubber aging. Hence, the influence of oil and thermal aging on the characteristics of NBR seals was studied by coupling the mechanical behavioral changes with the tribological behavioral changes of NBR in oil and the thermal environment. For this paper, aging testing and compression testing of NBR were carried out. Additionally, friction testing between friction pairs under different aging times was carried out. The surface morphology of the NBR working surface under different aging conditions was also observed. Finally, coefficients of different test conditions were introduced into the finite element model of NBR seals. It can be seen from the results that the elastic modulus increased with the increase in aging time in the thermal oxidative aging testing. The elastic modulus after 7 days of thermal oxidative aging increased by 135.45% compared to the unaged case, and the elastic modulus after 7 days of oil aging increased by 15.03% compared to the unaged case. The compression set rate of NBR increased significantly with the increase in aging time and temperature. The coefficient of friction (COF) between friction pairs increased first and then decreased with the increase in aging time. The maximum contact pressure decreased by 2.43% between the shaft and sealing ring and decreased by 4.01% between the O-ring and groove. The proportion of the effective sealing area decreased by 3.05% between the shaft and sealing ring and decreased by 6.11% between the O-ring and groove. Furthermore, the sealing characteristics between the O-ring and groove were better than those between the shaft and sealing ring.

Experimental and theoretical analysis on the thermomechanical properties of functionally graded graphene nanoplatelet reinforced cement composites

Graphene reinforced cement composites (GRCCs) have attracted great attention due to their excellent mechanical and physical properties. Instead of uniform distribution, the functionally graded distribution of graphene fillers can effectively utilize the mechanical and physical properties of the reinforcements while reducing cost. This paper is the first attempt to combine experimental analysis and theoretical modelling to investigate the thermomechanical properties of functionally graded graphene nanoplatelet (GNP) reinforced cement composites (FG-GNPRCCs). Samples with uniform (profile H) and functionally graded (profiles X, O and A) distribution of GNPs were prepared and tested. Among all the FG distribution patterns as involved, profile X exhibited the most pronounced enhancement. Compared to the uniform distribution at room temperature, the loss factor and storage modulus of profile X increased by 19.3 % and 19.5 %, respectively. Based on the effective medium theory (EMT) and Mori-Tanaka (MT) model, a parallel triple-inclusion model was developed to predict the thermal conductivity of GNPRCCs. The effects of coated GNP, agglomeration and the attributes of pores (i.e., size, shape and porosity) on the thermomechanical properties of the composites were considered. Dynamic mechanical analysis revealed that profile X had the best energy dissipation and the extent of inelastic deformation within the temperature range from −50 °C to 70 °C. In contrast, profile A is beneficial for scenarios that desire a gradual transition and controlled stress along a certain direction.

Comparative studies of radio transparency and dielectric characteristics of polymer composites

Aramid-epoxy composites and glass fiber reinforced plastics are widely used in the manufacturing of the fairing design for modern aerospace vehicles due to their excellent mechanical properties combined with radio transparency in wave transfer. In this paper, aramid-epoxy composite and fiberglass were fabricated by the vacuum infusion method for a comparative study on radio transparency and dielectric characteristics. The radio transparency of the studied materials was evaluated by free-space measurements in the frequency range of 1 GHz to 8.5 GHz. According to the radio transparency results, the aramid-epoxy composite undergoes less electromagnetic wave loss than glass fiber reinforced plastic. Modifying the epoxy resin with tricresyl phosphate in aramid-epoxy resin leads to an increase in mechanical properties with a slight decrease in transmittance and a non-significant increase in dielectric characteristics. The dielectric characteristics results have demonstrated low values (ε = 2.87 and tan δ = 0.037) for aramid composites compared to fiberglass.

Reversible photochromic effect and excellent mechanical properties of Nd3+-doped Zr6Nb2O17 purple ceramics

The development of colored ceramics is limited because it can only display a single color. Therefore, colored ceramics that can achieve reversible switching between two different colors can make up for this deficiency. In this study, we report a novel rare-earth doped colored ceramic, Zr6Nb2O17: xNd3+ (abbreviated as ZNO: xNd), which has been successfully obtained with good mechanical and photochromic properties of purple ceramics by component adjustment. The doping of rare earth Nd3+ ions changed the color of the ceramic matrix from light curry to light purple, and more importantly, enhanced its mechanical properties, with optimal Vickers hardness and fracture toughness values of 16.53 GPa and 5.2 MPa·m1/2, respectively. Alternating 365 nm irradiation and 350°C thermal stimulation, the ceramic samples exhibited good photochromic properties, with the highest photochromic contrast of 21.1 %, and good reversibility and cyclic stability. Finally, it is important to clarify that the photochromic mechanism is mainly caused by the formation of color centers resulting from electrons or holes being trapped by intrinsic or extrinsic defects. These results indicate that ZNO: xNd purple ceramics can be applied in the field of colored ceramics and provide a new path for the development of rare earth-colored ceramics.

One-step self-assembled biomass carbon aerogel/carbon nanotube/cellulose nanofiber composite for supercapacitor flexible electrode

Flexible and exceptionally lightweight energy storage devices are crucial for wearable electronic gadgets. Biomass materials are emerging as ideal flexible electrode components due to their biocompatibility and non-toxic nature. In this study, pineapple leaf fibers were utilized to create activated biomass carbon aerogel (Bio-CAA). Then, carbon nanotubes (CNTs) were integrated as conductive additives, combined with sturdy pineapple leaf cellulose nanofibers (CNFs) to establish a robust 3D framework. Utilizing a one-step self-assembly method, carbon aerogel/carbon nanotube/carbon nanofiber (Bio-CAA/CNT/CNF) flexible composite electrode materials were successfully synthesized. The porous structure of Bio-CAA effectively minimized the aggregation of CNTs, thereby significantly enhancing the electrochemical performance of the electrode material. The characterization indicated that the carbon aerogel composite exhibited a high specific surface area (684.275 m2 g−1) after tablet compression. The material was light yet robust, capable of being bent arbitrarily and recovering its original shape and withstanding 400 Kpa of pressure at an 88 % strain rate, demonstrating excellent mechanical properties. In a three-electrode system, the Bio-CAA/CNT/CNF = 19:1:1 based electrode exhibited a capacitance of 481 F g−1 at a current density of 1 A g−1. The CAA/CNT/CNF = 19:1:1 based solid symmetric supercapacitor (SSC) displayed excellent cycling stability, preserving 91.7 % capacitance after 10,000 cycles at a current density of 5 A g−1. It achieved an energy density of 39.63 Wh kg−1 at a power density of 500 W kg−1. This biomass-derived carbon aerogel-based composite material demonstrates exceptional energy storage capabilities, and its lightweight attributes make it highly suitable for use in flexible displays, wearable devices, and related fields.

Degradable polyvinyl alcohol/chitosan@carnauba wax superhydrophobic composite membrane for water-in-oil emulsion separation and heavy metal adsorption

At present, many oil-water separation membranes are being developed to purify oily wastewater. However, oily wastewater often contains heavy metal, which are often difficult to dispose during separation. Furthermore, most of the oil-water separation membranes cannot be degraded after scrap, producing pollution to environment. Herein, the polyvinyl alcohol/chitosan@carnauba wax (PCGCW) membrane with heavy metal adsorption and biodegradation performance was acquired by electrospinning and spraying process. The acquired PCGCW membrane had excellent mechanical properties after crosslinking glutaraldehyde (GA). Furthermore, the composite membrane had excellent superhydrophobic property (WCA = 154°) with a rolling angle of 2°, due to the introduction of carnauba wax. Exhilaratingly, for emulsions with surfactant, it had a high separation flux with 19,217 L·m−2·h−1·bar−1 and splendid an oil purity over 99.9 %. Besides, the efficiency of oil purity and separation flux remained stable even after 10 separations. In addition, the PCGCW membrane had the ability to adsorb heavy metals with adsorption capacity of 51–106 mg/g for Cu2+, Fe3+, Co2+ ions. Foremost, the superhydrophobic PCGCW membrane was biodegradable, with degrading 29.76 % within 40 days. The prepared composite membrane had the advantages of low cost, high separation flux, great repeatability, adsorbable heavy metals and degradability, which had a vast application prospect.

A robust bio-based polyurethane employed as surgical suture with help to promote skin wound healing

Designing bio-based polyurethane materials with excellent mechanical, biocompatibility, and self-healing properties simultaneously is currently a significant challenge due to the increasing demands for high-performance materials. In this study, we propose an asymmetric backbone strategy utilizing bio-based polycarbonate as the soft segment, equimolar ratios of lysine diisocyanate and isophorone diisocyanate as asymmetric hard segments, and isophorone diamine as the chain extender. The resulting polyurethane elastomers exhibit excellent mechanical properties, including high tensile stress (46.1 MPa), toughness (213.9 MJ/m3), and fracture energy (98.47 kJ/m3). The polyurethane elastomers demonstrate good self-healing and recyclable properties under simple heat treatment. Furthermore, biological experiments confirm the degradability and bio-safety of the bio-based polyurethane elastomers, which have shown potential in accelerating wound healing in mice when used as surgical sutures. These findings highlight the promising prospects of the obtained polyurethane elastomers in various applications, including biomedicine, flexible sensing, and electronic components.

Tough and conductive PVA-based double-network ionic hydrogels for flexible sensors

Hydrogels have been widely used for fabricating flexible sensors. However, it still remains a significant challenge to construct conductive hydrogels with excellent mechanical properties. This work presents a type of double-network (DN) hydrogels composed of poly(vinyl alcohol) (PVA) and poly(ionic liquids) (PILs), which are prepared through repetitive freezing/thawing process. Taking advantage of the coordination between carboxyl groups and Fe3+ ions, the mechanical properties of the DN hydrogels are enhanced after treated with Fe3+ ions. The influence of dosage of PILs and Fe3+ ions on the mechanical properties and conductivities of DN hydrogels is investigated. The DN hydrogel P(AVIM-AA)1/PVA-Fe3+4, which is prepared under optimal conditions, shows high tensile strength (1.75 MPa), elongation at break (375%), and toughness (2.75 MJ m-3). P(AVIM-AA)1/PVA-Fe3+4 also displays a good conductivity of 0.65 S m-1 and a high sensing sensitivity with a gauge factor of 2.766, indicating its potential application as flexible sensors.