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Quantitative explanation on the improved mechanical properties of aligned electrospun polyimide (PI) nanofibers as the increased imidization temperatures is highly required. In this work, polarized FT-IR spectroscopy is applied to solve this problem. Based on the polarized FT-IR spectroscopy and the molecular model in the fibers, the length of the repeat unit of PI molecule, the angle between the fiber axis and the symmetric stretching direction of carbonyl group on the imide ring, and the angle between the PI molecular axis and fiber axis are all investigated. The Mark-Howink equation is used to calculate the number-average molar mass of PI molecules. The orientation states of PI molecules in the electrospun nanofibers are studied from the number-average molar mass of PI molecules and the average fiber diameter. Quantitative analysis of the orientation factor of PI molecules in the electrospun nanofibers is performed by polarized FT-IR spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Poly(N‐isopropyl acrylamide) (PNIPAM) hydrogels are well known for their temperature‐dependent water uptake and release. Hence, they are ideal candidates for water management applications. However, efficiency and rate of water uptake and release, respectively, have to be optimized. Here, highly stable 3D PNIPAM sponges that show a sufficiently low density and high specific pore volume, required for maximizing the amount and rate of water absorption‐desorption, are presented. They are prepared by a top‐down approach based on freeze‐drying a dispersion of short crosslinked PNIPAM fibers coated with crosslinked PNIPAM. The sponges have low densities (4.10–21.04 mg cm−3), high porosities >98%, and high specific pore volumes in the range of 47–243 cm3 g−1 depending on the concentration of the dispersions. The sponges absorb high amounts of water (≈7000%) at temperatures below the lower critical solution temperature (LCST) of PNIPAM and can release more than 80% of the absorbed water above the LCST in less than 2 min. Moreover, the water‐swollen sponges are reversibly foldable, can be confined to different shapes, and have compressive elastic modulus below 10 Pa. Hence, these spongy materials are of interest not only for water management but also for biomedical applications, smart textiles, and catalysis. [ABSTRACT FROM AUTHOR]

Abstract: Low density (≤13.9 mg cm−3), compressible poly(bis(benzimidazo)benzophenanthroline‐dione) (BBB) sponges with high temperature resistance are reported. The processing of BBB is limited due to its insolubility in organic solvents and infusibility. Therefore, the sponges are made in two steps: first, the BBB fibers are prepared by electrospinning the starting monomers with a template polymer followed by polycondensation of monomers on solid fibers at high temperature. In the second step, the BBB fibers are mechanically cut and self‐assembled from a dispersion during freeze‐drying. The use of poly(vinyl alcohol) is critical in getting self‐assembled hierarchically double‐pore‐structured, mechanically stable sponges. The sponges show very high pyrolytic stability, high compressibility (more than 92% recovery after 50% compression), very low thermal conductivity (0.028–0.038 W mK−1), and high oil absorption capacity. [ABSTRACT FROM AUTHOR]

Ultralight cellular sponges offer a unique set of properties. We show here that solvent uptake by these sponges results in new gel-like materials, which we term spongy gels. The appearance of the spongy gels is very similar to classic organogels. Usually, organogels are formed by a bottom-up process. In contrast, the spongy gels are formed by a top-down approach that offers numerous advantages for the design of their properties, reproducibility, and stability. The sponges themselves represent the scaffold of a gel that could be filled with a solvent, and thereby form a mechanically stable gel-like material. The spongy gels are independent of a time-consuming or otherwise demanding in situ scaffold formation. As solvent evaporation from gels is a concern for various applications, we also studied solvent evaporation of wetting and non-wetting liquids dispersed in the sponge. [ABSTRACT FROM AUTHOR]

Thermoresponsive hydrogel fibrous membranes showing directionally controlled movements and surface change with ultra-fast speed are presented for the first time. They show reversible coiling, rolling, bending, and twisting deformations in different controllable directions for many cycles (at least 50 cycles tried) with inside-out change in surfaces and shapes. Speed, reversibility, large-scale deformations and, most importantly, control over the direction of deformation is required in order to make synthetic actuators inspired from natural materials or otherwise. A polymeric synthetic material combining all these properties is still awaited. This issue is addressed and provide a very simple system fulfilling all these requirements by combining porosity and asymmetric swelling/shrinking via orientation of hydrogel fibers at different angles in a fibrous membrane. Electrospinning is used as a tool for making membranes with fibers oriented at different angles. [ABSTRACT FROM AUTHOR]

1D fibers of Bombyx mori silk fibroin (SF) and poly( l-lactide) (SF-s-PLLA) with side-by-side parallel arrangement of the two components in a single fiber made by electrospinning are presented. The side-by-side arrangement in both randomly oriented and aligned two-in-one fibers was confirmed by scanning electron and confocal laser scanning microscope studies. The molecular orientation and secondary structure of SF and PLLA were dependent on the fiber alignment and annealing conditions. The two sides retained their individual secondary structure before and after annealing without affecting each other in a significant way. The two-in-one fibers after post treatment with methanol and heat at 80 °C showed tensile strength 16.5 ± 1.4 MPa, modulus 205 ± 20.6 MPa, and an elongation at break of 53 ± 8%. [ABSTRACT FROM AUTHOR]

Single electrospun copolyimide nanofiber and aligned co-PI nanofiber belts with high strength and high modulus were prepared from copolyamic acid containing pyrimidine units. The chemical structures of copolyamic acid and copolyimide were characterized by 1H-NMR and FT-IR spectra. The morphology of the electrospun nanofibers was investigated by SEM and AFM. The mechanical properties of the single electrospun nanofiber and aligned nanofiber belts were measured by the single fiber micro-tensile test and the uniaxial tensile test, respectively. The thermal properties of the co-PI nanofiber belts were evaluated on TGA and DMA machines. The results indicated that the incorporation of rigid pyrimidine units, the molar ratio of pyrimidine/4,4′-oxydianiline and the imidization temperature played an important role in the mechanical properties of electrospun copolyamic acid and copolyimide nanofibers while the thermal properties were influenced by the molar ratio of rigid and soft components in the copolyimide main chains. [ABSTRACT FROM AUTHOR]

Mechanically strong electrospun nanofibers at high temperature are highly desired in the aerospace industry, high temperature filtration and fire protection clothing. In the present work, highly tough poly(imide-co-benzoxazole) (PI-co-PBO) nanofiber belts with excellent thermal stability, mechanical properties and thermomechanical properties were produced from the highly viscous methoxy-containing polyamic acid (MeO-PAA) solution by electrospinning followed by thermal rearrangement. The chemical structures of the polymer nanofibers and the corresponding thermal rearrangement were confirmed by 1H-NMR, FT-IR and TGA. The mechanical properties and thermomechanical properties were characterized by a tensile test and thermomechanical analysis (TMA). The aligned nanofiber belts heat-treated at 450 °C (ANF-450) had the highest tensile strength of 559 MPa, a modulus of 11.2 GPa and a toughness of 12.0 J g−1, respectively, which were much higher than those of the pure PBO films made by thermal rearrangement. The TMA test showed that the ANF-450 exhibited a high tensile strength retention of 90% and a modulus retention of 94% at a high temperature of 200 °C. These excellent thermomechanical properties make electrospun PI-co-PBO nanofibers promising candidates in high temperature areas. [ABSTRACT FROM AUTHOR]

Mechanical properties of polyimide (PI) electrospun nanofibers could be improved by increasing imidization temperatures. However, the intrinsic mechanism on this phenomenon is highly required, which is helpful to improve mechanical properties of electrospun nanofibers by external thermal treatment. In this work, single electrospun PI nanofibers (SNF-PI) with different imidization temperatures were prepared. The nanofiber morphology was studied by SEM and AFM and the mechanical properties were measured by single fiber micro-tensile test. Polarized Raman Spectroscopy was applied to determine the PI molecular orientation in SNF-PI. The molecular orientation factor provides directly explanation on the effect of imidization temperatures on the mechanical properties of SNF-PI. [ABSTRACT FROM AUTHOR]

Electrospun polyimide (PI) nanofibers possessed high tensile strength (δ), but the breaking load (BL) is very small. It is also a challenge to prepare electrospun PI microfibers from the PAA precursor in high boiling point solvents. In this work, PI microfibers with diameter more than 2 μm were prepared from their PAA-salt in water mixed with low boiling point solvent, such as ethanol. The single electrospun PI microfiber (S-EPIMF) showed excellent mechanical properties with BL, δ, modulus and tensile strain of 4872 μN, 1064 MPa, 5.6 GPa and 15.7%, respectively. The high BL allows a single electrospun PI microfiber even be able to hold a 0.5 g metal ring. The superior mechanical properties of the electrospun PI microfibers could be attributed to the high molecular orientation and crystallinity in the fibers, and the high BL is due to the large diameter of the electrospun PI microfibers. [ABSTRACT FROM AUTHOR]

Ultralight polymer sponges are prepared by freeze-drying of dispersions of short electrospun fibers. In contrast to many other highly porous materials, these sponges show extremely low densities (<3 mg cm−3) in combination with low specific surface areas. The resulting hierarchical pore structure of the sponges gives basis for soft and reversibly compressible materials and to hydrophobic behavior in combination with excellent uptake for hydrophobic liquids. Owing to their large porosity, cell culturing is successful after hydrophilic modification of the sponges. [ABSTRACT FROM AUTHOR]

High mechanical performance materials at high temperature are highly desired for the materials used in high temperature industries. This study reports the aligned electrospun polyimide nanofiber belt (A-PI-NFB) fabricated from the electrospinning followed with imidization. The A-PI-NFB showed increased mechanical and thermal mechanical properties as increasing the imidization temperature. At room temperature, the A-PI-NFB imidized at 450 °C (A-PI-NFB-450) had the highest tensile strength (689 MPa) and E modulus (13.2 GPa). The thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA) showed that A-PI-NFB-450 possessed 80% tensile strength and 90% modulus when heated at 300 and 350 °C in N 2 , respectively. These excellent properties made A-PI-NFB good candidates for use in high temperature filtration, protective clothes etc. [ABSTRACT FROM AUTHOR]

Template assisted change in morphology from particles to nanofibers was shown for low molar mass amphiphilic block copolymers by side-by-side electrospinning. The reversibly cross-linkable particles and fibers could be easily obtained from the same polymeric material by choosing proper processing conditions and spinning nozzles. The conventional electrospinning with single-component nozzle provided only particles. The morphology of the particles was controlled by varying the electrospraying conditions and characterized by SEM, optical microscope, and AFM. The same low molecular weight non-spinnable polymers provided fibrous morphology by Template Assisted Method (TAM) using side-by-side electrospinning nozzle with PEO as sacrificial polymer. [ABSTRACT FROM AUTHOR]

Highlights: [•] Heat-resistant electrospun PBO nanofibers were prepared from precursor OH-PAA. [•] The obtained PBO nanofibers are thermally stable up to 643°C. [•] The obtained PBO nanofibers have excellent mechanical properties. [•] PBO nanofibers have retention of tensile strength and modulus over 80% at 350°C. [•] Such heat-resistant PBO nanofibers could be used in high temperature fields. [ABSTRACT FROM AUTHOR]

Polyamide-imides (PAIs) are highly desired in many applications because of their superior thermal and mechanical properties. In this work, PAI was prepared from an amide-containing diamine and dianhydride by polycondensation and thermal treatment. Both PAI films and aligned electrospun nanofibers (ANFs) were fabricated. FT-IR was used to determine the structure formation of PAI at different annealing temperatures. DSC and TGA were used to evaluate the thermal properties of PAI, while tensile test was applied to evaluate the mechanical properties of PAI films and ANFs. The results indicated that the PAI possessed both outstanding thermal stability and mechanical properties, which provide opportunities for applications in gas separation, high temperature filtration, reinforcement, etc. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, preparation method and actuation properties of an innovative composite membrane composed of thermo‐ and pH‐responsive poly(N‐isopropylacrylamide‐co‐acrylic acid) fibers (average diameter ≈ 905 nm) embedded within a passive thermoplastic polyurethane (TPU) matrix at different angles with degree of alignment as high as 98% are presented. The composite membrane has a gradient of TPU along the thickness. It has the capability of temperature‐ and pH‐dependent direction‐, and size‐controlled actuation in few minutes. The stresses generated at the responsive fiber and nonresponsive matrix provide actuation, whereas the angle at which fibers are embedded in the matrix controls the actuation direction and size. The temperature has no effect on actuation and actuated forms at pH 7 and above, whereas the size of the actuated forms can be controlled by the temperature at lower pH. The membranes are strong enough to reversibly lift and release ≈426 times weight of their own mass (2.47 g metal ring is lifted by a 5.8 mg membrane). Soft actuators are of interest as smart scaffolds, robotics, catalysis, drug release, energy storage, electrodes, and metamaterials. [ABSTRACT FROM AUTHOR]

Tantalum carbide has been widely used as an excellent refractory material. However, there are no reports regarding the continuous tantalum carbide-carbon nanofibers (TaC/CNFs) and their mechanical and electrical properties. In this work, TaC/CNFs were prepared by electrospinning. The morphology and structures of the nanofibers and the distribution of TaC in the nanofibers were investigated by SEM, EDX, TEM, XRD, XPS and Raman spectroscopy. The TaC/CNFs showed excellent thermal stability, mechanical flexibility and conductivity even after folding for 180 cycles. These flexible, refractory and conductive TaC/CNFs could be found potential applications for flexible electronic devices and refractory materials. [ABSTRACT FROM AUTHOR]

The occurrence of fluoride contamination in drinking water has gained substantial concern owing to its serious threat to human health. Traditional adsorbents have shortcomings such as low adsorption capacity and poor selectivity, so it is urgent to develop new adsorbents with high adsorption capacity, renewable and no secondary pollution. In this work, magnetic electrospun La-Mn-Fe tri-metal oxide nanofibers (LMF NFs) for fluoride recovery were developed via electrospinning and heat treatment, and its defluoridation property was evaluated in batch trials. Modern analytical tools (SEM, BET, XRD, FTIR) were adopted to characterize the properties of the optimized adsorbent, i.e., LMF11 NFs with a La:Mn molar ratio of 1:1. The surface area calculated via BET method and pHpzc assessed using pH drift method of LMF11 NFs were 55.81 m2 g−1 and 6.47, respectively. The results indicated that the adsorption amount was highly dependent on the pH of the solution, and reached the highest value at pH = 3. The kinetic behavior of defluoridation on LMF11 NFs was dominated by the PSO model with the highest fitted determination coefficients of 0.9999. Compared with the other three isotherm models, the Langmuir model described defluoridation characteristics well with larger correlation coefficients of 0.9997, 0.9990, 0.9987 and 0.9976 at 15 °C, 25 °C, 35 °C and 45 °C, respectively. The optimized LMF11 NFs exhibited superior monolayer defluoridation capacities for 173.30–199.60 mg F−/g at pH 3 at 15–45 °C according to the Langmuir isotherm model. A thermodynamic study proved that the defluoridation by LMF11 NFs is a spontaneous, endothermic along with entropy increase process. In addition, the LMF11 NFs still showed high defluoridation performance after three reused cycles. These findings unveil that the synthesized LMF11 NFs adsorbent is a good adsorbent for fluoride remediation from wastewater owing to its low cost, high defluoridation performance and easy operation. [ABSTRACT FROM AUTHOR]

Titanium carbides are well-known for their outstanding mechanical and thermal stabilities. However, the studies on the mechanical properties and the conductivity of titanium carbide–carbon nanofibers (TiC/CNF) are missing. This work prepared TiC/CNF by electrospinning and highlighted the high modulus of single TiC/CNF, the flexibility and the excellent electrical conductivity of TiC/CNF felt even under 100 bending cycles. This flexible TiC/CNF felt with distinguished mechanical and electrical properties are promising to apply in titanium matrix composites (TMC), efficient catalyst scaffolds and electronic devices. [ABSTRACT FROM AUTHOR]

Crosslinked poly(ST- co -DVB- co -NaSS) latex nanoparticles (LNPs) with average particle size were used as template to prepare porous carbonized electrospun nanofibers (CENFs) with pore size about 10 nm on the surface and inside by electrospinning and carbonization. The porous CENFs without and with MWCNTs exhibited high specific surface area of 505 and 535 m 2 /g and high mesoporosity percentage of 80% and 84% respectively. The porous CENFs as electrode materials for electrochemical capacitors in 1 M H 2 SO 4 showed a specific capacitance of 235 F/g while the addition of MWCNTs led to an increase to 262 F/g. These free-standing and binder-free mesoporous CENFs with outstanding capacitance could be good candidates as electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]

A three-phase nanocomposite with outstanding dielectric properties was prepared via electrospinning and hot-pressing, by which multi-walled carbon nanotubes (MWCNTs) were homogeneously dispersed in polyimide (PI) matrix and separated by the BaTiO 3 particles (BTPs). The fairly enhanced dielectric properties were due to synergistic enhancing of the ferroelectric ceramic filler BTPs and conductive filler MWCNTs. The investigation shows that the dielectric permittivity of the as-fabricated three-phase nanocomposites with 40 vol% BTPs and 10 vol% MWCNTs loads is as high as 1061.98 at 100 Hz with a lower dielectric loss of 0.23, and the corresponding energy storage density is 4.773 J/cm 3 , 11 times that of the pure polyimide. The three-phase nanocomposites with enhanced dielectric properties also show excellent thermal properties and will be attractive in application in modern microelectronics. [ABSTRACT FROM AUTHOR]

Abstract: Copolymers, poly(acrylonitrile-co-monobutylitaconate-co-n-butylacrylate) (copolyacrylonitrile, co-PANs) with different content of monobutyl itaconate (MBI) were synthesized by free radical polymerization and then electrospun into aligned nanofibers. After thermal treatments of stabilization, carbonization, and graphitization, the resulting aligned co-PAN nanofibers were converted to aligned electrospun carbon nanofiber bundles (ECNFB) with diameters of approximately 200nm. FT-IR technique was applied to investigate the stabilization process of co-PAN nanofibers, while XRD, TEM and tensile tester were used to characterize the microstructures and mechanical properties of the ECNFB. The measured results revealed that MBI was a fairly useful comonomer for preparing high performance PAN-based CNFs by improving the stabilization of co-PAN nanofibers and by promoting the formation of ordered graphite crystals in the ECNFB. When the content of MBI unit in co-PAN was 5wt%, the aligned ECNFB exhibited a tensile strength of up to 1.8GPa and a Young׳s modulus of up to 97.0GPa, which is 86% and 67% higher than those of the ECNFB previously reported in our group respectively. [Copyright &y& Elsevier]

An alternative magnetic field (AMF)-induced electrospun fibrous thermoresponsive composite actuator showing penetrable remote-control ability with fast response is shown here for the first time. The built-in heater of magnetothermal Fe3O4 nanoparticles in the actuator and the porous structure of the fibrous layer contribute to a fast actuation with a curvature of 0.4 mm−1 in 2 s. The higher loading amount of the Fe3O4 nanoparticles and higher magnetic field strength result in a faster actuation. Interestingly, the composite actuator showed a similar actuation even when it was covered by a piece of Polytetrafluoroethylene (PTFE) film, which shows a penetrable remote-control ability. [ABSTRACT FROM AUTHOR]

Flexible materials with high mechanical strength and good dielectric properties are highly desired for modern electronics. In this research, all-organic PVDF/PI nanofiber-reinforced composites were fabricated by layer-by-layer hot-pressing the random PVDF nanofibers and aligned co-PI nanofibers. Dielectric and mechanical properties of the PVDF/PI composites were investigated. Results showed that the mechanical properties were highly enhanced by the aligned co-PI nanofibers and the dielectric permittivity was inherited from the intrinsic good dielectric properties of PVDF. These all-organic PVDF/PI composites with excellent mechanical strength and good tunable permittivity can be used for flexible embedded capacitors and can be further employed as the polymer matrix for preparing high dielectric polymer–matrix composites. [ABSTRACT FROM AUTHOR]

Graphical abstract The preparation of superhydrophobic and superoleophilic PI-based nanofibrous membrane for oil-water separation. Abstract Marine pollution and industrial wastewater have caused serious environmental pollution, thereby resulting into an alarming damage to public health in the past decades, hence the high demand for, cost effective, energy-efficient oil-water separation technologies for the removal of oil contaminants from such water. Herein, we report a facile method to fabricate superhydrophobic/superoleophilic membrane by immersing a polyimide (PI)-based nanofibrous membrane into a water/ethanol/ammonia/dopamine mixture, followed by modification with 1H, 1H, 2H, 2H-perfluorodecanethiol (PFDT). The PI-based membrane exhibited water contact angle (WCA) above 153°, while the oil contact angle (OCA) approached 0°, thereby promoting an outstanding chemical stability which sustained its superhydrophobicity when immersed in aqueous solutions at different pH values. Additionally, the PI-based membrane possesses ultrahigh flux, high separation efficiency and good reusability in oil-water separation. The aforementioned properties, as well as the easily scale-up preparation process ensure that this promising as-fabricated membrane can be applied for practical environmental applications including treatment of oily wastewater and oil spillage clean-up. [ABSTRACT FROM AUTHOR]

High mechanical performance carbon nanofibers are highly required for the carbon nanofiber-reinforced composites, and it is necessary to develop novel precursors for the preparation of carbon nanofibers. In this work, blends of poly(acrylonitrile-butyl acrylate mono-butyl itaconate) (co-PAN) and polyamic acid (PAA) were electrospun into aligned nanofibers and the nanofibers were converted to carbon nanofibers by thermal imidization, pre-oxidation and high-temperature carbonization. FT-IR spectroscopy was applied to monitor the chemical structures of the nanofibers before and after pre-oxidation. Tensile tests were used to characterize the mechanical properties of electrospun carbon nanofibers (ECNFs). The microstructures of ECNFs were investigated by high-resolution TEM and Raman spectroscopy. The results indicated that the ECNFs derived from blend of co-PAN/PAA with molar ratio of 6/4 and with carbonization temperature of 1400 °C possessed the highest tensile strength of 1212 MPa, which could be attributed to the ordered graphitic structures in ECNFs. [ABSTRACT FROM AUTHOR]

Abstract: Nature is an intriguing inspiration for designing a myriad of functional materials. However, artificial mimicking of bioinspired structures usually requires different specialized procedures and setups. In this study, a new upscalable concept is presented that allows to produce two bioinspired, bicomponent fiber morphologies (side‐by‐side and coaxial bead‐on‐string) using the same electrospinning setup, just by changing the employed spinning solvent. The generated fiber morphologies are highly attractive for thermoresponsive actuation and water harvesting. Another challenge solved in this work is the compositional characterization of complex fiber morphologies. Raman imaging and atomic force microscopy is introduced as a powerful method for the unambiguous characterization of complex bicomponent fiber morphologies. The work opens the way for the construction of heterostructured fiber morphologies based on different polymers combinations, offering high potential for applications as actuators, smart textiles, water management, drug release, and catalysis. [ABSTRACT FROM AUTHOR]

Electrospinning is a well-known technique for the preparation of scaffolds for biomedical applications. In this work, a continuous electrospinning method for gel fiber preparation is presented without a spinning window. As proof of concept, the preparation of poly(aspartic acid)-based hydrogel fibers and their properties are described by using poly(succinimide) as shell polymer and 2,2,4(2,4,4)-trimethyl-1,6-hexanediamine as cross-linker in the core of the nozzle. Cross-linking takes place as the two solutions get in contact at the tip of the nozzle. The impact of solution concentrations and feeding rates on fiber morphology, proof of the presence of cross-links as well as pH sensitivity after the transformation of the poly(succinimide)-based material to poly(aspartic acid) is presented. [ABSTRACT FROM AUTHOR]

Electrospinning is a common method for preparing nanomaterials. Among many electrospinning materials, electrospun carbon nanofibers (CNFs) have become one of the hot research directions for advanced functional materials owing to their good mechanical properties, high surface area, excellent flexibility, physical and chemical stability. Particularly, significant progress has been made in the engineering advancement of electrospinning, electrospun CNFs and their derived reinforced composites to fulfill various applications. This review aims to afford a comprehensive overview of electrospun CNF reinforced composites. Firstly, the different precursors, the correlative properties, and surface modification strategies (e.g. , physical modification and chemical modification) of electrospun CNFs are introduced. Secondly, the preparation methods of reinforced composites based on electrospun CNFs are described in detail. Then, the functional applications of electrospun CNF reinforced composites are discussed. Finally, the challenges and future solutions of electrospun CNF reinforced composites are also prospected. This review is expected to offer a basic but deep understanding of modification strategies to heighten the surface performances of CNFs for the future development of high-performance electrospun CNF reinforced composites in the composite industry, defense, and aerospace applications. [Display omitted] • Electrospun CNF reinforced composites are widly used in engineering materials. • The precursors and modification strategies of electrospun CNFs are detailly reviewed. • Diverse preparation and application of CNF reinforced composites are summarized. • The current challenges of electrospun CNF reinforced composites are discussed. • The future prospects of CNF-based composites in advanced engineering are proposed. [ABSTRACT FROM AUTHOR]

Polyaniline/polyimide (PANI/PI) composites with hierarchical 3D micro/nano-architecture have been prepared via electrospinning and in-situ polymerization. The PANI/PI composite prepared from 0.2 M aniline (PANI/PI-2) exhibited a small average pore size (1.730 μm) and a narrow pore size distribution (1.552–1.882 μm). Compared to the commercial polyolefin separators, the PANI/PI composite separator possesses a much better thermal stability up to 180 °C, a higher porosity (84%), a larger liquid electrolyte uptake (619%) and a higher ionic conductivity (2.33 mS cm −1 ). The cell with PANI/PI-2 composite separator showed a low interfacial resistance, an enhanced capacity (133 mAh g −1 at 0.2C), a better rate capability (41.4% at 10C) and cyclability (89.3% retention after 500 charge/discharge cycles at 0.2C). The PANI/PI composite with a superior thermal stability and high electrochemical performances is a promising candidate for uses in high perform LIBs. [ABSTRACT FROM AUTHOR]

Short carbon nanofibers (SCNFs) were prepared by electrospinning followed with grinding and ultrasonic breaking and employed as fillers to prepare polyimide (PI) composites. The dielectric and mechanical properties of SCNFs/PI composites were investigated. Results showed that the SCNFs have significant improvement in mechanical properties and are good conductive filler for preparing high dielectric composites. Compared to the neat PI, the SCNFs/PI composite with 1 wt% SCNFs showed 39.43% improvement in tensile strength. The SCNFs/PI composites showed a low percolation threshold of 4 wt% for the dielectric permittivity (60.79 @100 Hz). These electrospun SCNFs reinforced PI composites can be good candidate for making high performance dielectric materials for modern electronic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The actuator can achieve synergistic movement of deformation and transportation. • Added Fe 3 O 4 NPs provide both magnetism and high-efficient photothermal conversion. • The hydrogel actuator owns high tensile-strength of 4.59 MPa via electrospinning. • The actuator can provide ultrafast deformational speed of 178°/s. • We have explored new bio-inspired systems with two/multi-step synergic actuation. As a soft/wet intelligent material, hydrogel actuators with multiple stimuli-responsiveness have been widely developed. However, it is still greatly difficult for them to integrate bi/multiple responsiveness together for bio-mimetic synergistic actuation. Here, we have explored a high-strength anisotropic bi-layer hydrogel actuator with P(NIPAM-ABP) layer and Fe 3 O 4 /PAN layer via electrospinning technique, which can provide programmable bi-functional synergistic movement. The Fe 3 O 4 /PAN layer can provide magnetic responsive navigation for long-range transportation on account of the magnetism of the Fe 3 O 4 nanoparticles. Furthermore, the ultrahigh photothermal conversion efficiency of the Fe 3 O 4 nanoparticles in the Fe 3 O 4 /PAN layer, can endow the P(NIPAM-ABP) layer with fast remotely-controlled photothermal-responsive deformation. Most importantly, this hydrogel actuator can achieve complex higher-level programmable movements than before based on the synergy of remotely-controlled deformation and the long-range transportation, which can be utilized to design various novel bio-mimetic soft-robots. Last but not least, the introduction of the electrospinning, not only can achieve high strength (4.59 MPa of tensile strength) of this bi-layer hydrogel, but also can provide both ultrafast (178°/s) and programmable complex photothermal-responsiveness, owing to the ultrahigh specific surface area (ultra-thin and porous structure) and excellent orientation of the thermal-responsive P(NIPAM-ABP) nanofibers respectively. This work will provide a general method via electrospinning for anisotropic hydrogel actuator with bi/multiple-functional synergy and will provide a new strategy for smart actuators and other bio-mimetic intelligent materials/systems. [ABSTRACT FROM AUTHOR]

Electrospinning is an effective and versatile method to prepare continuous polymer nanofibers and nonwovens that exhibit excellent properties such as high molecular orientation, high porosity and large specific surface area. Benefitting from these outstanding and intriguing features, electrospun nanofibers have been employed as a promising candidate for the fabrication of food packaging materials. Actually, the electrospun nanofibers used in food packaging must possess biocompatibility and low toxicity. In addition, in order to maintain the quality of food and extend its shelf life, food packaging materials also need to have certain functionality. Herein, in this timely review, functional materials produced from electrospinning toward food packaging are highlighted. At first, various strategies for the preparation of polymer electrospun fiber are introduced, then the characteristics of different packaging films and their successful applications in food packaging are summarized, including degradable materials, superhydrophobic materials, edible materials, antibacterial materials and high barrier materials. Finally, the future perspective and key challenges of polymer electrospun nanofibers for food packaging are also discussed. Hopefully, this review would provide a fundamental insight into the development of electrospun functional materials with high performance for food packaging. [ABSTRACT FROM AUTHOR]

Interventions and policies for tackling air pollution issues exist and have been proven to be effective. Membrane materials of nanofibrous morphology are attractive for air filtration, and further alleviate the environmental issues. Electrospinning as a simple and versatile way to fabricate ultrafine fibers has been attracting tremendous attention. Herein, the recent researches and future trends of green electrospinning are expounded from the aspects of green degradable materials, green solution electrospinning, and solvent‐free electrospinning. The green degradable materials, including biomass materials, biosynthetic polymer materials, and chemical synthetic materials are reviewed. Following the concept of green electrospinning, electrospun polymer nanofibers via aqueous solution are discussed; additionally, further trends of solvent‐free electrospinning including melt‐electrospinning, anion‐curing electrospinning, UV‐curing electrospinning, thermo‐curing electrospinning, and supercritical CO2‐assisted electrospinning are highlighted. Furthermore, the applications of these electrospun nanofibrous membranes in the field of air filtration are discussed. In the end, the challenges of green electrospinning and future prospects are summarized. The development of green electrospinning is reviewed with an emphasis on current advanced solvent‐free research, where electrospun nanofibrous membranes are contributing to promising treatment strategies to solve environment issue. Herein, the recent researches and future trends of green electrospinning are expounded. Following the concept of green electrospinning, electrospun polymer nanofibers via aqueous solution and further trends of solvent free electrospinning are discussed. The development of green electrospun nanofiber membranes is reviewed where green electrospun scaffolds are contributing to promising treatment strategies to air pollution. [ABSTRACT FROM AUTHOR]