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Abstract: This paper describes the effects of polyimide (PI) structure on electrical conductivity of blends of dodecylbenzene sulfonic acid-doped polyaniline (PANI-DBSA) and PI, as well as its thermal degradation behavior. Four types of PIs with different molecular architecture were synthesized and subsequently solution blended with PANI-DBSA. Of the four types of PIs, 4-4′-diaminodiphenyl sulfone (DADPS)-based PI provides the highest conductivity to the blends. It is attributed to the rigid nature of DADPS, which may induce more extended conformation of PANI chains, and hence result in a more ordered structure. The conductivity of the blends has significant higher thermal stability than that of PANI-DBSA. The thermal stability is, however, independent on the polyimide structure. TGA studies show that the PI matrix may have hindered the thermo-oxidative degradation and evaporation of the dopants and thus slowed down the process of thermal degradation of the conductivity. [Copyright &y& Elsevier]

This paper describes the effect of molecular weight of dopants on thermal degradation behaviour of electrical conductivity of polyacrylic acid (PAA) doped polyaniline (PANI). Two PAA with weight-average molecular weight (Mw) of 5000 and 250,000, respectively, were used as dopants to synthesise PANI–PAA complexes by in situ oxidative polymerisation. PANI doped with the low Mw PAA has lower electrical conductivity, which is attributed to its smaller size of crystal islands due to the end group effect. When annealed at 180 °C, within a period of 2 h the conductivity of PANI doped with the high Mw PAA decreases continuously with the annealing time following σ=σ0 exp[−(ta/τ)1/2] law, while the one doped with the low Mw PAA obeys this law only within 1 h of annealing. This indicates that the decrease of conducting island size is responsible for the thermal degradation of the conductivity of the complexes in a certain period and the length of this period depends on Mw of the dopants. TGA study shows that at 180 °C weight loss rates of the low and high Mw PAA doped PANI are about the same, which implies that the faster reduction of the conductivity in the low Mw PAA doped PANI is mainly due to its smaller initial crystal size. FT-IR study shows that annealing leads to de-doping, but it is less pronounced in the high Mw PAA doped PANI. [Copyright &y& Elsevier]

Polyaniline (PANI) doped with dodecylbenzene sulphonic acid (DBSA) and methylbenzene sulphonic acid (MBSA) were used as model compounds to investigate thermal degradation mechanisms of electrical conductivity of PANI salts. The effects of high temperature annealing on the conductivity, thermal stability and morphology of the doped PANI were studied. Within a period of 2 h, the conductivity of the two PANI salts decreases continuously with the annealing time. The conductivity reduction also increases significantly with the annealing temperature. Both polymers show significant weight loss during the annealing, especially at 200 °C. The weight loss of PANI–MBSA is more pronounced than that of PANI–DBSA, while the conductivity reduction shows an opposite trend. Scanning electronic microscopy (SEM) study reveals a significant morphology change caused by the annealing. Fourier transformed infrared (FT-IR) results indicate that some dopants are converted to free acids due to the annealing. It is, therefore, suggested that in addition to cross-linking of PANI and evaporation and degradation of the dopants, the segregation of the dopants from the polymers is also an important mechanism responsible for the conductivity degradation observed. [Copyright &y& Elsevier]

The fast growing demand for advanced sportswear suitable for tropical countries has led to research on fabrics with both moisture wicking and anti-bacterial properties. In this work, to improve the water transport behaviour, dual-layer nanofibrous nonwoven mats composed of a hydrophilic polyacrylonitrile (PAN) outer layer and a hydrophobic poly(vinylidene fluoride) (PVDF) inner layer are fabricated by electrospinning. The distinct difference in surface hydrophobicity between the inner and outer layers induces a push-pull effect to transport water from the inner to the outer surface efficiently. To render an antibacterial property, zinc oxide (ZnO) nanoparticles are covalently attached to the PVDF nanofibers. The good anti-wash properties and anti-bacterial function of the ZnO-PDVF/PAN dual layer mats are demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Supercritical-CO 2 foaming of polypropylene (PP)/heptaisobutyl open-cage silsesquioxane (HOS) nanocomposites. • HOS, a low-cost hybrid Janus molecule, act as a surfactant during the foaming of PP/HOS nanocomposite. • HOS content at cell surface is higher than that in cell walls; stabilises growing cells and reinforces solidified cells. • Expansion ratio and compressive strength of PP/HOS-1 wt% foam are 38% and 20% higher than that of PP foam, respectively. • With ≤1 wt% HOS, it also slightly improves extensional viscosity and strength of the melt at low strain rates. High-melt-strength (HMS) polypropylene (PP) has enabled easy supercritical-CO 2 (scCO 2) foaming of PP. However, producing microcellular PP foams via simple scCO 2 extrusion foaming still remains challenging, whereas macrocellular PP foams with high expansion ratios (ER) generally exhibit poor mechanical strengths. In this study, to simultaneously enhance both ER and compressive strengths of macrocellular PP foams, a type of low-cost Janus molecules, heptaisobutyl open-cage silsesquioxane (HOS), is incorporated into HMS-PP. Since HOS has PP-philic groups and a partially condensed silsesquioxane cage that is relatively CO 2 -philic, it could diffuse like a surfactant to the PP-CO 2 interface during scCO 2 extrusion foaming to stabilise the cells in their growth stage and reinforce the cell surface upon solidification. The surfactant effect is validated via X-ray Photoelectron Spectroscopy. Moreover, with 1 wt% HOS, the PP/HOS foam could offer 38 % ER improvement, 23 % density reduction, and 20 % compressive strength increase over the neat PP foam. HOS could also slightly improve the extensional viscosity and melt strength of PP at ≤1 wt% loadings and reduce the shear viscosity of PP by acting as a lubricant. This approach provides a simple and economically viable materials design guideline for alleviating ER-compression strength trade-offs for macrocellular polymer foams. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we report novel epoxy-based hybrids prepared via incorporating 1,2-dimethyl-3-(benzyl-heptaisobutyl-POSS) imidazolium chloride (POSS-IMC) and POSS-IMC-modified clay (POSS-MMT) into the resin based on 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (ECHM) and hexahydrophthalic anhydride (HHPA). We demonstrate that both POSS-IMC and POSS-MMT can reduce the cure temperature of the epoxy/anhydride system, and the catalyzing effect involves chemical reactions between POSS-IMC and ECHM/HHPA, which may lead to the attachment of POSS cages at chain ends. The incorporation of the POSS-IMC, free and ionically bonded in clay, gives rise to dissimilar morphologies that affect the thermo–mechanical properties of the hybrids. The ECHM/HHPA/POSS-IMC resin exhibits a slight improvement in glassy modulus as compared with the neat ECHM/HHPA resin, which is attributed to the formation of sub-micron and nano-sized POSS domains that act as physical cross-link points hindering polymer chain motions. The much enhanced reinforcing effect of POSS-MMT is ascribed to the effective stress transfer between the matrix and clay layers that may originate from the strong interactions between the pendent POSS in the network and POSS attached to the clay surfaces. Reduction in coefficient of thermal expansion (CTE) was also found for the hybrids. [Copyright &y& Elsevier]

In this paper, a novel method for fabrication of core-shell nanospheres with polystyrene (PS) as the core and multi-walled carbon nanotubes (MWNTs) as the shell via hydrogen-bonding self-assembly is introduced. The PS nanospheres with carboxyl acid groups on the surface (PS–COOH nanospheres) were prepared by typical soap-free emulsion copolymerization with acrylic acid as comonomer. The MWNTs were grafted with poly(vinyl pyrrolidone) (PVP), in which the carbonyl oxygen can act as proton acceptors to form hydrogen bonds with the carboxyl acid groups. The results show that the functionalized MWNTs can self-assemble onto the surface of PS–COOH nanospheres rapidly via hydrogen bonding interaction, and the process is reversible and can be well controlled by adjusting pH value of the system. These core-shell nanospheres have the potential to be used as conductive and synergistic reinforcement fillers in fabricating high-performance and functional nanocomposites. [Copyright &y& Elsevier]

• Elabela is a recently identified peptide which activates the apelin receptor. • Elabela is a potential treatment target for ischemia/reperfusion injury. • Fc-ELA-21 has a long in vivo half-life and is effective in acute kidney injury. • Akt phosphorylation has a role in the anti-apoptotic effect of elabela. Renal ischemia/reperfusion injury (IRI) is the most common cause of acute kidney injury (AKI), and patients with AKI have a high rate of mortality. Apelin is a therapeutic candidate for treatment of IRI and Elabela (ELA) is a recently discovered hormone that also activates the apelin receptor (APJ). We examined the use of ELA as a preventive treatment for IRI using in vitro and in vivo models. Male mice were subjected to renal IRI, with or without administration of a stabilized form of ELA (Fc-ELA-21) for 4 days. Renal tubular lesions were measured using H&E staining, reactive oxygen species (ROS) were measured using a dihydroethidium stain assay, and renal cell apoptosis was measured using the TUNEL assay and flow cytometry. Immortalized human proximal tubular epithelial (HK-2) cells were pretreated with or without LY294002 and/or ELA-32, maintained at normoxic or hypoxic conditions, and then returned to normal culture conditions to mimic IRI. Cell apoptosis was determined using the TUNEL assay and cell proliferation was determined using the MTT assay. The levels of Akt, p-Akt, ERK1/2, p- ERK1/2, Bcl-2, Bax, caspase-3 and cleaved caspase-3 were measured using western blotting. Fc-ELA-21 administration reduced renal tissue damage, ROS production, and apoptosis in mice that had renal IRI. ELA-32 reduced HK-2 cell apoptosis and restored the proliferation of cells subjected to IRI. Akt phosphorylation had a role in the anti-apoptotic effect of ELA. This study of in vitro and in vivo models of IRI indicated that the preventive and anti-apoptotic effects of ELA were mediated via the PI3K/Akt signaling pathway. [ABSTRACT FROM AUTHOR]

Abstract Polyaniline (PANI) is one of the most widely used organic electrode materials for supercapacitors. It has advantages such as good environmental stability and low cost, whereas it is difficult to achieve high capacitance, good rate capability and long cycle life simultaneously. In this work, a series of porous polyaniline/carbon nanotube (PANI/CNT) composite materials are prepared by chemically grafting PANI on CNTs and creating interpenetrating pores via templating using CaCO 3 nanoparticles, and then studied as electrode materials for supercapacitors. As PANI is covalently grafted on CNT networks formed in the electrode, the delocalization of electrons improves electron transport in the electrode and the stability of PANI in redox cycling process. The porous morphology created provides sufficient channels for the transport of ions. As a result, the optimized PANI/CNT composite exhibits a high capacitance of 1266 F g−1 at a specific current of 1 A g−1, and even at a specific current of 128 A g−1 the specific capacitance could reach 864 F g−1. Moreover, after cycling tests of 10,000 cycles, it remains 83% of its capacitance at the first cycle. The excellent rate performance and cycle stability of the porous PANI/CNT composite makes it a promising high-performance electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract Honeycomb-like lignin-derived carbon (LC) foams doped with reduced graphene oxide (RGO) are fabricated via unidirectional ice-templating followed by freeze-drying and carbonization. The dimensions, constituent contents, and density of the foams could be easily adjusted. By manipulating the density, high electrical conductivity and good mechanical properties could be achieved at relatively low RGO contents. In addition to the high conductivity and interfaces between LC and RGO, aligned pores also boost electromagnetic interference (EMI) shielding effectiveness (SE) of the foams owing to induced multiple reflections. X-band EMI SE of the LC-based foams with 2-mm thickness could reach 28.5–70.5 dB at very low densities. Furthermore, the normalized surface specific SE (SE divided by density and thickness) could be as high as 28750 dB cm2/g, which is much higher than those of other types of carbon foams and most shielding materials ever reported. With the outstanding EMI shielding performance, good mechanical properties and more sustainable raw material, the biomass-based carbon foams offer promising prospects for lightweight, robust and high-performance EMI shielding materials. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

While approaches have been successfully devised to optimize the power factor of inorganic thermoelectric (TE) materials, the understanding and control of TE performance of organic composite materials are however still rudimentary due to their complicated structures and weak interfacial interactions. We report a facial method to tailor the interfacial interaction of amine-functionalized carbon nanotubes (A-CNT)/polyaniline (PANI) composites, which results in composites exhibiting high conductivity (2012 S cm −1 ) and excellent power factor (273 μW m −1  K −2 ) with A-CNT content of 94 wt%. By tuning PANI/camphor sulfonic acid mole ratios, the power factor is further improved to 401 μW m −1  K −2 , which is higher than that of most reported organic TE materials. Beside the optimum carrier concentration, we attribute the outstanding TE property to the existence of amine functional groups on CNT that facilitate the formation of highly conductive network and a unique PANI interlayer of up to ∼10 nm that interacts strongly with A-CNT, facilitates charge transfer and endows the composites with high electrical conductivity, as evident by TEM, Raman, XRD, and solubility studies. [ABSTRACT FROM AUTHOR]

In this paper, we report graphene nanoscrolls bridged by crumpled graphene nanosheets as an effective conductive framework for confining SnS 2 nanosheets for lithium-ion battery (LIB) applications. The nanoscroll/nanosheet hybrid aerogels (GNAs) with confined SnS 2 nanosheets are facilely prepared via fast quenching, freeze-drying and thermal annealing. During quenching, wrapping SnS 2 nanosheets in the nanoscrolls and bridging the one-dimensional nanoscrolls by the two-dimensional nanosheets occur simultaneously, and the ratio of nanoscrolls/nanosheets can be controlled by simply adjusting quenching conditions. The optimized SnS 2 /GNA is highly porous with a large specific surface area of 127.1 m 2  g −1 and multi-scale pore structure, which can effectively prevent SnS 2 aggregation to provide abundant lithiation/delithiation sites, and buffer volumetric change and pulverization of SnS 2 nanosheets. Moreover, the three-dimensional conductive network formed in the hybrid aerogels can remarkably improve its electrical conductivity while providing sufficient channels for the transportation of lithium ions and charges. As a result, the optimized SnS 2 /GNA nanocomposite exhibits enhanced electrochemical performance with a high initial reversible capacity (1514.8 mAh g −1 at 0.1 A g −1 ), excellent rate capacity (665.4 mAh g −1 at 5 A g −1 ) and good cyclic stability (1050 mA h g -1 at the 50 th cycle). This may provide an efficient generic approach for encapsulation of transition metal dichalcogenide materials in conductive nano/micro confined spaces for fabrication of high-performance LIB anodes. [ABSTRACT FROM AUTHOR]

In this work, the surface of stacked-cup carbon nanofibers (CNFs) was coated with polydopamine (PDA) via a facile biomimetic method based on catecholic chemistry. The modified CNFs (D-CNFs) were incorporated into an epoxy resin in a solvent-free manner. In addition to hydrogen bonding, covalent bonding is also present between amino groups in PDA and epoxy, as verified by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Owing to the strong interfacial interactions brought by PDA, D-CNFs show significantly improved dispersibility in epoxy matrix. Consequently, the reinforcing effects of D-CNFs clearly outperform those of pristine CNFs (P-CNFs), especially in terms of fracture toughness. Dynamic thermo-mechanical studies show that the addition of D-CNFs can increase storage modulus more effectively without deteriorating the thermal stability of epoxy matrix. This study confirms that enhancing interfacial interactions in polymer composites by coating nanofillers with PDA is a useful strategy to obtain simultaneous stiffening and toughening in rigid thermoset polymers. [ABSTRACT FROM AUTHOR]

Unstable crack propagation behavior of carbon fiber reinforced plastic (CFRP) composites has a significant impact on the safety and reliability of structures in practical applications. Herein, we reported a method to improve the stability of crack growth by coating polydopamine (PDA) and graphene oxide (GO) on the surface of carbon fabric. The Mode I and Mode II tests were performed to study the delamination and crack behaviors of pure CFRP and modified CFRP. The crack propagation behavior can be tuned from unstable to stable manner without sacrificing the crack initiation during the opening mode test. It was revealed that the crack tended to fracture through the GO sheets, leading to the tearing and peeling of GO. The PDA&GO coated layers contributed to improving the load transfer between carbon fibers and polymer matrix, reducing the crack blunting degree, minimizing the unstable crack growth, and thus dissipating more energy. [ABSTRACT FROM AUTHOR]

The fracture toughness of carbon fiber reinforced plastic laminates was investigated in term of modifying the epoxy matrix with the pristine and functionalized stacked-cup carbon nanofibers. The results showed that the highest enhancements in Mode I (13.6%) and Mode II (45.3%) fracture toughness were achieved by adding 0.5 wt% and 1.0 wt% functionalized nanofibers, respectively. The toughening mechanism was analyzed based on the morphology evaluations of the fracture surfaces. The evidence of bridging, pull-out, peeling-off and unravelling of nanofibers were clearly observed, which contributed to dissipating more energy for crack propagation, resulting in the improvement of fracture toughness. [ABSTRACT FROM AUTHOR]

Layer-by-layer assembly method is employed to fabricate multilayer hybrid films based on poly(styrenesulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) and tungsten oxide nanoparticles (WO 3 NPs). Polyethylenimine (PEI) is deposited in between to introduce electrostatic force between the components. In the hybrid films, randomly oriented disk-like WO 3 NPs are homogeneously distributed in the polymers and form an interdigitated structure. This very rough surface morphology hinders the formation of a continuous PEI layer between the electrochromic layers. Owing to the efficient charge transfer between the two active components and complementary electrical conductivity of the two components in the redox switching process, the coloration efficiency of the hybrid film is significantly improved to 117.7 cm 2 /C at wavelength of 633 nm. The underlying mechanism for the enhancement is verified by scanning electrochemical microscopic studies through probing the conductivity changes of PEDOT:PSS, WO 3 -NP and hybrid films under various applied potentials. [ABSTRACT FROM AUTHOR]

In this work, graphene is facilely prepared by direct exfoliation of graphite in aqueous media with the assistance of alkali lignin (AL). The graphite is successfully exfoliated into single- and multi-layer graphene, with about 20% monolayer ones, and the concentration of graphene in the aqueous dispersions can reach 0.65 ± 0.03 mg mL −1 . The nanosheets are stabilized in the dispersions owing to π–π interaction between the graphene and AL, and the electrostatic repulsion between negative charged AL, as verified by fluorescence and zeta-potential measurements. The results also show that there are very few defects in the basil-plane of the graphene so that the free-standing graphene films prepared from the dispersions exhibit good electrical conductivity. Finally, the addition of only 0.1 wt% such graphene sheets to an epoxy resin gives 15%, 49%, and 97% enhancement in tensile strength, critical stress intensity factor and critical strain energy release rate, respectively. [ABSTRACT FROM AUTHOR]

Mesoporous zinc ferrite (ZnFe 2 O 4 )/graphene composites are synthesized using a facile ambient-pressure method, i.e., co-precipitation of metal cations onto graphene oxide followed by solid state reaction to yield ZnFe 2 O 4 nanoparticles anchored on reduced graphene oxide. The resultant ZnFe 2 O 4 /graphene composites have large specific surface area with mesopores, and the size of the ZnFe 2 O 4 nanoparticles is less than 20 nm. When the composites are employed as an anode material for lithium-ion batteries, it exhibits superior electrochemical performances in term of high reversible capacity, good cyclic performance and excellent rate capability. Its reversible discharge capacities can be maintained at 870 mAh/g at 1.0 A/g for 100 cycles and consecutively 713 mAh/g at 2.0 A/g for another 100 cycles. Moreover, other graphene-based composites containing ferrites, such as cobalt ferrite and nickel ferrite, are also synthesized with this generic strategy which is promising for large-scale production of lithium-ion battery anode materials. [ABSTRACT FROM AUTHOR]

Zinc ferrite (ZnFe 2 O 4 ) nanorods are synthesized using a facile and scalable method, i.e., decomposition of oxalate precursors which are obtained through a polyvinyl alcohol-assisted aqueous precipitation reaction. The ZnFe 2 O 4 nanorods are further coated with carbon by self-polymerization of dopamine on the surfaces of the ZnFe 2 O 4 nanorods followed by carbonization. The carbon layer on the ZnFe 2 O 4 nanorods is homogeneous with the thickness of 3 to 5 nm. The polydopamine-derived carbon coating greatly improves the electrochemical performances of the ZnFe 2 O 4 nanorods, especially rate capability and cycling stability. When galvanostatic diacharging/charging at 0.5 and 2 A/g, the ZnFe 2 O 4 /carbon nanorod anode can deliver reversible capacities of 805 and 504 mAh/g, respectively, whereas the ZnFe 2 O 4 nanorod anode only delivers the capacities of 616 and 154 mAh/g, respectively. Besides, the ZnFe 2 O 4 /carbon nanorod anode shows excellent cycling stability; no obvious capacity fading is observed at the current density of 1 A/g for 100 cycles. The improved electrochemical performances could be attributed to the enhanced electron conductivity of the ZnFe 2 O 4 nanorods with the carbon layer, which is confirmed by electrochemical impedance spectroscopy measurements and scanning electron microscopic studies of the cycled electrodes. [ABSTRACT FROM AUTHOR]

Electrospun polymer nanofibrous mats loaded with ionic liquids (ILs) and lithium salts are promising non-volatile electrolytes owing to their high ionic conductivities. However, the large cations of ILs are difficult to diffuse into solid electrodes, whereas the lithium ions in ILs tend to form anionic complexes with the IL anions, reducing the number of free lithium ions. To address these issues, octa(3-hydroxy-3-methylbutyldimethylsiloxy) polyhedral oligomeric silsesquioxane (POSS-OH), which has large specific surface area and functionality number, is incorporated into electrospun poly(vinylidene fluoride -co- hexafluoropropylene) (PVDF- co -HFP) nanofibrous mats, and the mats are used to host LiClO 4 /1-butyl-3-methylimidazolium tetrafluoroborate (BMIM + BF 4 − ). It is found that POSS-OH can significantly increase both ionic conductivity and lithium transference number of the electrolytes owing to the Lewis acid-base interactions of POSS-OH with ClO 4 − and BF 4 − . The electrochromic device using the hybrid mat (with 5 wt% POSS-OH) loaded with LiClO 4 /BMIM + BF 4 − as the electrolyte shows significantly improved transmittance contrast and switching time, as a result of increased number of free lithium ions. [ABSTRACT FROM AUTHOR]

The usage of zinc oxide (ZnO)-based nanostructures in photoelectrochemical (PEC) water splitting has been well investigated yet still in keen exploration for further performance enhancement. Multi-walled carbon nanotubes (MWCNTs)-modified ZnO nanorods were prepared via hydrothermal route followed by simple solution deposition. MWCNTs were self-anchored onto the ZnO nanorods and acted as a hole-attracting phase. The PEC performance of MWCNTs-modified ZnO nanorods, including photocurrent density and photo current conversion efficiency (PCE), was found to be significantly improved compared with unmodified ones. The maximum value of PCE (0.646%), which was 2.1 times higher than that of pristine ZnO nanorods, was achieved with a MWCNTs/ethanol suspension concentration of 0.002 wt%. The performance enhancement is attributed to increasing of light absorption from rougher surface and effective charge carrier transport from the excellent conductivity of the incorporated MWCNTs. [ABSTRACT FROM AUTHOR]

Abstract: CuInZnS-decorated graphene (CIZS@graphene) is prepared via a hydrothermal process and investigated as an anode material for lithium-ion batteries. CIZS@graphene exhibits an initial discharge capacity of 1623 mA.h g−1 at 100 mA g−1, and at a high rate of 2000 mA g−1 its reversible capacity is steadily increased from 389 mA h g−1 to 494 mA h g−1 in 480 cycles, demonstrating promising stable cycling performance at high rates. Electrochemical impedance spectroscopic studies show that charge-transfer resistances of CIZS@graphene reduces after cycling at high rates, justifying the excellent high-rate performance and stability of the CIZS@graphene anode. [Copyright &y& Elsevier]

Abstract: In this work, ultrathin free-standing electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) nanofibrous mats are realized through the use of 1,3-diaminopropane as the chemical cross-linking agent. The cross-linking reaction occurs within the nanofibers as well as between the nanofibers that are in touch, forming relatively strong inter-fiber junctions and hence resulting in remarkable improvement in structural integrity of the electrospun mats with very small thickness. The chemically cross-linked electrospun mats are used as the host for 1-butyl-3-methylimidazolium tetrafluoroborate to prepare ionic liquid (IL)-based polymer electrolytes, and the effects of cross-linking on swelling and crystallization behaviors of the mats are studied. The results show that with a low degree of cross-linking, a high ionic conductivity of 2.6 mS/cm can be achieved, which is mainly due to the presence of a significant amount of free ILs in the interpenetrating pores of the mats. An electrochromic device is fabricated using this electrolyte to demonstrate the potential of the mat as IL host, especially its capability to greatly reduce IL consumption. [Copyright &y& Elsevier]

Abstract: This article reports the preparation of nylon 6/stacked-cup carbon nanofiber (CNF) nanocomposites via in situ anionic ring-opening polymerization partially initiated from caprolactam-functionalized CNFs. As a result of the successful functionalization of CNF surface, good dispersion of the CNFs was observed by transmission electron microscopy (TEM). Moreover, with the addition of a very small amount of CNFs, significant enhancements in tensile modulus and yield strength were achieved together with slightly improved impact resistance. The enhanced stiffness may be attributed to effective filler–matrix stress transfer induced by interfacial covalent bonds. On the other hand, SEM micrographs provided evidence for the possible unraveling of the stacked-cup CNF, which may allow the CNFs to bridge the matrix during crack propagation, hence resulting in the toughening of the nanocomposites. [Copyright &y& Elsevier]

Abstract: Novel triazole-functionalized carbon nanofibers (m-CNFs) were prepared by one-step arylation with diazonium salts generated in situ. Microscopic observations indicate that m-CNFs exhibit significantly improved dispersibility in a high-performance epoxy resin compared with pristine CNFs (p-CNFs). The results of DSC and SEM show evidence of interfacial reaction and a more robust interface between m-CNFs and the epoxy matrix. Thermal and mechanical properties of two CNF/epoxy composites were systematically studied at different filler loadings. The results show that both CNF fillers could reinforce the epoxy matrix without sacrificing their thermal properties. Benefiting from the improved dispersibility and interfacial interaction, the ability of m-CNFs in toughening the epoxy resin is clearly superior to p-CNFs. The addition of only 0.4wt% m-CNFs gives 41% and 80% enhancement in critical stress intensity factor (K IC) and the critical strain energy release rate (G IC), respectively. [Copyright &y& Elsevier]

Highlights: [•] Poly(aniline-co-3-amino-4-hydroxybenzoic acid) (PAAHBA) was prepared. [•] Morphology and electrochemical activity of PAAHBA were studied. [•] PAAHBA film shows a nanostructured network of mass interwoven fibers. [•] PAAHBA film exhibits improved electrochemical properties under highly basic conditions. [Copyright &y& Elsevier]

Abstract: In this article, we report a novel fullerene–polyaniline emeraldine base (C60–PANI-EB) hybrid synthesized through covalent bonding of polyaniline (PANI) onto para-phenylenediamine (PPD)-functionalized fullerene and its capacity properties. C60–PANI-EB exhibits a unique coral-like porous morphology with PANI particles interconnected by nanofibers. In comparison with polyaniline emeraldine base (PANI-EB), C60–PANI-EB shows significantly higher specific capacitance, specific power and specific energy, and better cycling stability. The specific capacitance of C60–PANI-EB and PANI-EB are 776Fg−1 and 492Fg−1 at current density of 1mAcm−2, respectively. The specific capacitance of C60–PANI-EB has 37% enhancement over that of PANI-EB even at high current density of 100mAcm−2. The specific energy of C60–PANI-EB is 64Whkg−1 at 1mAcm−2 and the specific power is 36,595Wkg−1 at current density of 100mAcm−2. The greatly enhanced capacity performance can be attributed to the increased ionic conductivity induced by the loose molecular packing structure and porous morphology as well as the increased electrical conductivity caused by the coral-like interconnected morphology and the strong electron-withdrawing function of the fullerene through its covalent bonding to PANI. [Copyright &y& Elsevier]

Abstract: In this work, the effects of single-walled carbon nanotubes (SWCNT) surface chemistry on the polymorphism behaviors of electrospun poly(vinylidene difluoride) (PVDF) nanofibers collected under high extensional force and subsequently treated with supercritical carbon dioxide (SCCO2) are investigated via X-ray diffraction, infrared and Raman spectroscopy. It is found that the SWCNTs with hydroxyl groups (h-SWCNTs) interact with PVDF chains more intensively than the ones with ester groups, and the interaction in couple with the high extensional force promotes the formation of β-form extended-chain crystallites (ECCs). With the SCCO2 treatment, the growth of the β-form ECCs is further promoted in the PVDF/h-SWCNT nanofibers owing to the synergistic effect of the strong confinement effect of h-SWCNT for stabilizing the nuclei of the β-form ECCs and the high pressure applied. [Copyright &y& Elsevier]

Abstract: In this article, fullerene covalently bonded with multiple polyaniline (PANI) arms (C60-PANI) was readily synthesized via copolymerization of aniline with p-phenylenediamine (PPD) functionalized fullerene in the presence of poly(styrene sulfonate) (PSS) dopant agent in an aqueous medium to produce a water-processable electrochromic material. The PSS-doped C60-PANI (C60-PANI:PSS) film possesses finer morphology in comparison with PSS-doped PANI (PANI:PSS) film. Owing to the electron acceptor characteristic and high conductivity of fullerene as well as the loose morphology of C60-PANI:PSS, the synthesized hybrids exhibit simultaneously enhanced electrical and ionic conductivities, resulting in improvement of electrochromic performance. In particular, the electrochromic device with C60-PANI:PSS as the active layer shows significant enhancement in optical contrast and electrochemical stability over the PANI:PSS-based device. [Copyright &y& Elsevier]

Abstract: In this work, the effects of thermal annealing on the structures and properties of an ionic liquid (IL) of 1-butyl-3-methylimidazolium hexafluorophosphate-loaded supercritical carbon dioxide-treated electrospun poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP) membrane were studied and compared with a corresponding IL/PVDF-HFP gel membrane. The results show that although the annealing causes slight distortion of the nanofibers as well as some small changes in crystallinity and crystal size, the nanofibrous and microporous morphology of the membrane is not altered and hence the membrane can retain its high optical transparency and ionic conductivity after the annealing, whereas the gel exhibits significantly reduced optical transmittance and ionic conductivity owing to annealing-induced phase separation. The IL/PVDF-HFP electrospun membranes before and after annealing were used as the electrolyte layer in electrochromic devices, respectively. The device with the annealed IL/PVDF-HFP electrospun membrane shows no performance deterioration, demonstrating the potential of such thermally stable electrolyte for electrochromic devices used in harsh environments. [Copyright &y& Elsevier]

Abstract: A new series of electrochromic polymers are synthesized via oxidative emulsion copolymerization of hexa(4-aminophenoxy)cyclotriphosphazene (HACP) and aniline in the presence of dodecylbenzene sulfonic acid. The structures of the copolymers are characterized using nuclear magnetic resonance spectroscopy, size exclusion chromatography, wide angle X-ray diffraction, scanning and transmission electron microscopy. The results reveal that the copolymer containing 4.0mol % HACP (4.0% HACP–PANI) possesses a large number of nanometer-sized crystallites due to the unique molecular architecture of HACP–PANI. Spectro-electrochemical studies show that 4.0% HACP–PANI exhibits a significant enhancement in electrochromic contrast as compared with homopolyaniline (PANI). The contrast enhancement can be attributed to the easier diffusion of cations into nanometer-sized crystals, which is evidenced by a significant increase in ionic conductivity. At lower HACP concentrations, the copolymers induce the crystallization of linear PANI as substantial amounts of PANI may form during the polymerization, resulting in increased crystal size, and hence low electrochromic contrasts. [Copyright &y& Elsevier]

In this article, we report highly porous yet robust microhoneycomb-like nanofibrous aerogels (NFAs) with porous cell walls and hierarchical porous structures, and their potential as durable high-performance air filters. The NFAs are fabricated from cellulose nanofibers and kraft lignin via directional ice-templating and low-temperature annealing. We found that lignin could effectively boost cross-linking reactions during the annealing, greatly enhancing the mechanical robustness of the NFAs. It also effectively minimizes annealing-induced shrinkage of the NFAs, avoiding significant porosity and pore-size reduction. Our filtration test results reveal that these robust NFA filters exhibit excellent filtration performance for particles over a wide range of sizes, including 0.1 μm and most penetrating particles. In particular, a high filtration efficiency of 99.86% with a fairly low pressure drop (ΔP) of 59.5 Pa could be achieved for 0.1 μm particles at the face velocity of ∼5 cm s−1, for which the corresponding quality factor (QF) is significantly higher than that of reported aerogel air filters fabricated using predominantly natural materials. The outstanding QF achieved could be attributed to the preferably aligned pores and porous cell walls that help to ease the airflow and create longer and tortuous travelling paths for diffusive particles while within the pores the loose, tangled nanofibers with surface functional groups could facilitate particle deposition. Moreover, heavy loading filtration tests show good long-term filtration efficiency and anti-clogging features of the NFAs. Overall, this work provides a new strategy to prepare durable NFA air filters that are capable of mitigating the tradeoff between the filtration efficiency and ΔP, and alleviating the potential microplastic pollution caused by the disposal of petroleum-based plastic filters into environments. [Display omitted] • Honeycomb-like nanofibrous aerogel (NFA) is prepared using cellulose and lignin. • Hyperbranched lignin could boost crosslinking and reduce thermal-induced shrinkage. • NFA shows excellent filtration performance for quasi ultrafine and 0.3 μm particles. • Unidirectional pores could ease the airflow and introduce anti-clogging properties. • Environmentally benign strategy capable of mitigating efficiency-ΔP tradeoff. [ABSTRACT FROM AUTHOR]

Abstract: By attaching separate, parallel electrodes onto a rotating disk collector, well aligned electrospun polyvinylidene difluoride (PVDF), PVDF/carbon nanotube nanocomposite and vinylidene fluoride–trifluoroethylene copolymer nanofibers are directly deposited onto flat substrates forming relatively large, uniform and compact fibrous thin films. The attachments alter the electric-field distribution on the rotating disk, which fosters the fanning of the nanofibers, while the electric field between the separate electrodes and the mechanical force exerted by the rotational disk facilitate the alignment. X-ray diffraction and infrared spectroscopic studies show that the specific environment and force fields created on the modified rotating disk cause the electrospun fibers being effectively stretched to form highly oriented β-form crystallites with slightly reduced inter-chain distance. They also lead to slight increases in crystallinity and crystal size. A mechanism is proposed to account for the structural alteration induced by the modified rotating disk collector. Ferroelectricity of the aligned electrospun PVDF fibrous thin films is also demonstrated. [Copyright &y& Elsevier]

Abstract: We report the structures, electrochemical and electrochromic properties of organic–inorganic hybrid polymers prepared via copolymerization of octa(aminophenyl) silsesquioxane and aniline. Compared with homopolyaniline (PANI), this class of novel materials exhibits much greater thermodynamic penetrability in solution, as detected using static and dynamic light scattering, suggesting that they have a star-like molecular geometry. Due to their star-like geometry, in solid state the copolymers (POSS–PANI) exhibit a loosely packed structure with relatively low crystallinity, as evidenced by X-ray and TEM characterization, and hence relatively high ionic conductivity. Cyclic voltammetric studies show that POSS–PANI undergoes similar electrochemical reactions to that of PANI but its loosely packed structure allows slightly faster cation diffusion. Spectro-electrochemical studies show a ∼40% enhancement in electrochromic contrast brought by tethering PANI onto POSS, which can be attributed to more accessible doping sites in POSS–PANI. Furthermore, the electrochemical stability of POSS–PANI is also significantly improved over that of PANI. Infrared spectroscopic measurements indicate that the formation of electrochemically inactive quinonediimine is retarded in POSS–PANI possibly due to the increased conformation freedom of the dopant anions. [Copyright &y& Elsevier]