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Flexible electronic devices have attracted considerable attention in recent years. Textile fabrics have been widely used to fabricate flexible strain sensors owing to their high flexibility. However, the elasticity of ordinary textile fabrics is low, which limits their strain sensing range. In this article, we used a simple method to fabricate flexible strain sensing fabrics (FSSFs) through the coating of graphene oxide (GO) nanosheets on elastic nylon/polyurethane (nylon/PU) fabric, followed by reduction of GO with sodium borohydride. The reduced graphene oxide (RGO) nanosheets were adsorbed on the elastic fabrics to impart electrical conductivity to the fabrics. The coated fabrics were characterized with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman scattering spectroscopy. The electromechanical performance and strain sensing properties of the FSSF were investigated. The fabricated strain sensor exhibited high sensitivity, a large workable strain range (0–30%), fast response and great stability. The mechanical property of fabrics did not change remarkably after the treatment with RGO. The surface resistance of the RGO/nylon/PU only increased from ∼112 KΩ/m 2 to ∼154 KΩ/m 2 after 8 washing cycles, exhibiting good washability. Furthermore, real-time monitoring of human motions, such as bending of finger and rotation of wrist, was achieved by the as-prepared FSSF. The RGO/nylon/PU fabrics as flexible strain sensors have potential applications in wearable electronic devices. [ABSTRACT FROM AUTHOR]

To perform bending fatigue tests on fiber materials, a specially designed bending fatigue test apparatus has been developed. The test apparatus was equipped with a temperature control system and a Xenon lamp irradiation system, and thereby the test can be done in controlled environments such as temperature and light irradiation conditions. Using this apparatus, bending fatigue tests on Kevlar 49 and PBO fibers were performed. The test results showed that the bending fatigue strength of Kevlar49 and PBO fibers was strongly influenced by temperature and light irradiation. The σ–N and σ–lnN curves indicated that the pre-tension had significant effects on the bending fatigue life and the fatigue life decreased when temperature became high. In addition, the fatigue strength of fibers tested with light irradiation was lower than that without light irradiation. [ABSTRACT FROM AUTHOR]

• An efficient and stable SO 4 2−/TiO 2 -SiO 2 catalyst was developed for MMA production. • The Brønsted and Lewis acid site densities and ratios in catalyst can be modulated. • The cooperative catalytic effects between Brønsted and Lewis acid sites were noticed. • The catalytic pathway on such catalyst was confirmed as L-H mechanism. Either the ethylene or isobutene-based route for industrial production of methyl methacrylate (MMA) contains the esterification step between methacrylic acid (MAA) and methanol, therefore it is necessary to develop highly active and stable catalyst. Herein, series of superacid catalysts of SO 4 2-/TiO 2 -SiO 2 were prepared for esterification of MAA with methanol to produce MMA. The Brønsted and Lewis acid site densities and their ratios in SO 4 2-/TiO 2 -SiO 2 could be modulated by controlling the impregnated (NH 4) 2 SO 4 concentration, which were identified by pyridine titration and FT-IR. And no changes in structural skeleton and crystal phase of the SO 4 2-/TiO 2 -SiO 2 during the acid properties regulation process were noticed with FT-IR and XRD. The cooperative catalytic effects between Brønsted and Lewis acid sites were observed through catalytic evaluation. The kinetic studies indicated the catalytic pathway followed L-H mechanism and the activation barrier of forward esterification (48 kJ/mol) was greater than that of reverse hydrolysis (40 kJ/mol) step. [ABSTRACT FROM AUTHOR]

• Series of basic ionic liquids with sterically hindered cations were synthesized. • An ionic liquid catalyzed process for 4-hydroxy-2-butanone synthesis was developed. • The steric hindrance effect on selectivity of product was found and demonstrated. • The catalytic pathways and reaction kinetic were revealed. 4-Hydroxy-2-butanone as important chemical intermediate in the field of both pharmaceutical and food industries is traditionally synthesized from formaldehyde and acetone via aldol reaction with relatively low selectivity due to the heavy side reactions. Herein, series of basic ionic liquids with different sterically hindered cations were prepared for this reaction process. The catalytic performance evaluation results revealed the selectivity of 4-hydroxy-2-butanone could be enhanced with the extension of alkyl chain length substituted in the cation of ionic liquid and increasing number of substituted alkyl group. And the tetraoctyl ammonium hydroxide ([N8,8,8,8]OH) was identified as the optimal ionic liquid catalyst with selectivity of 91.1% toward 4-hydroxy-2-butanone at 40 °C. The kinetic studies indicated the formation of 4-hydroxy-2-butanone was first-order dependent on both acetone and formaldehyde concentrations, with the lowest activation barrier of 49.8 kJ/mol among all steps. [ABSTRACT FROM AUTHOR]

[Display omitted] • Collagen/carboxylated CNF composite aerogels are successfully fabricated. • CDs can promote the in vitro self-assembly behavior of collagen. • CDs are beneficial for improving the properties of the collagen composite aerogels. • Composite aerogels have an excellent pH-responsive for drug delivery system. pH-responsive materials have great potential for use in various advanced fields, such as microreactors and drug delivery. This work proposes a promising strategy for preparing composite aerogels with pH-responsive properties based on collagen (COL) and TEMPO-oxidized cellulose nanofibers (CNFs) through the self-assembly behavior of COL molecules for controlled-drug release. COL fibrils and carboxylated CNFs (cCNFs) exhibited a high-density, physical cross-linked supramolecular double network structure. Specifically, cyclodextrins (CDs) were introduced to optimize the structural stability and slow-release capability of the composite aerogels. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analyses were used to characterize the structure of the aerogels, and the swelling behavior and water contact angle of the aerogels were evaluated. Using 5-fluorouracil (5-FU) as the model drug, the slow-release mechanism was subsequently revealed. Compared with the COL aerogels and COL/cCNF composite aerogels, the COL/cCNF@CD composite aerogels exhibited enhanced structural stability and slow-release performance through the synergistic enhancement effect of cCNFs and CDs. The aerogels also exhibited sensitivity to pH for regulating 5-FU release, and the COL composite aerogels with CDs and cCNFs maintained excellent cytocompatibility. In conclusion, CDs had a positive effect on the structural stability and pH-responsiveness of the composite aerogels and promoted the possible utilization of aerogels in drug delivery systems. [ABSTRACT FROM AUTHOR]

Recycling of photocatalyst in wastewater treatment is a big challenge. Fixation of photocatalyst on a flexible surface of solid substrates is a promising solution. In this work, copper ferrite (CuFe 2 O 4) particles were loaded onto polydopamine (pDA) pretreated ceramic/polyester fabrics (CPF) via coprecipitation. The CPF not only acts as loading material for CuFe 2 O 4 particles, but also makes this photocatalyst convenient to recycle. The morphology, elemental composition and structure of the as-fabricated CPF/CuFe 2 O 4 were characterized by scanning electron microscope (SEM), Fourier transform Infrared (FT-IR) spectrometer, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer (XRD). The degradation rate of methylene blue (MB) by the CPF/CuFe 2 O 4 photocatalyst reached to 98.2% under visible light irradiation for 80 min, reflecting the excellent photocatalytic activity of the composites. The CPF/CuFe 2 O 4 demonstrated good photostability and recoverability, indicating its great potential in wastewater treatment. Moreover, the degradation mechanism and possible degradation pathway of MB by CPF/CuFe 2 O 4 photocatalyst were investigated. [ABSTRACT FROM AUTHOR]

• Durable core-sheath electro-thermochromic CNT/cotton composite yarn was fabricated. • The yarn shows excellent mechanical properties and thermochromic performance. • The yarn exhibits excellent electrified heating performance with stability. • The yarn is durable against mechanical deformations, washing and chemicals. • The color of the yarn can be tuned by changing the applied current for design. A core-sheath nanocomposite yarn, with CNT/cotton composite yarn (CCY) as the core and nanofibrous polyurethane/temperature sensitive ink as the sheath, was fabricated to generate highly robust and durable electro-thermochromic performance. Due to its novel core-sheath nanocomposite structure, the as-fabricated electro-thermochromic composite yarn (ECCY) brought together the excellent mechanical properties and electrothermal properties together with electrochromic performance. The ECCY exhibited excellent electrified heating performance with stability even after 100 cycles of heating/cooling. Moreover, the ECCY showed excellent durability against repeated bending, twisting and stretching, washing and even soaking in acid and alkali solutions. The color of ECCY was successfully tuned via changing the applied current. In addition, the ECCY was used to design different patterns and to form a fabric, resulting in color conversion patterns/fabrics when applying/releasing a current. This work provides a novel strategy of developing electro-thermochromic composite yarn by designing the core-sheath micro-nano fibrous composite structure. The highly robust and durable performance of yarn will benefit its applications as wearable electronics. [ABSTRACT FROM AUTHOR]

• Implementing in situ hydrothermal growth of Cu NPs on textiles. • Introducing polydopamine as a template to facilitate growing nanoparticles. • Fibrous structure has been preserved with nanoparticles deposited on fibers. • Durable and highly-flexible textile based wearable sensor was developed. Incorporating conductive components into fibrous structure for wearable applications has attracted research attention recently. However, utilizing the flexibility and wearability of textiles to maintain a stable and durable wearable performance is a big challenge, as the intrinsic properties of textiles and the conductivity of the incorporated components have to work synergically in the fibrous system without compromising. In this work, polydopamine-templated PET fabrics were prepared to grow copper nanoparticles (Cu NPs) on the surface of the knitted PET fabrics. The surface morphology, chemical composition and crystalline structure of the Cu NP-coated PET fabrics were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The results showed that Cu NP layer was successfully deposited onto the polydopamine-templated PET fabrics. The fabrics showed excellent electrical conductivity due to the loading of Cu NPs. The unique knitted structure together with the durable deposition of Cu NPs resulted in negative change in electrical resistance of the fabrics under strains, granting the fabrics the potential in wearable applications. The Cu NP-coated PET fabrics were demonstrated to be applicable as wearable strain sensors and electrical heaters. [ABSTRACT FROM AUTHOR]

With fiber-based wearable electronics being developed and widely used in various fields, the safety and durability of nanomaterials in fibrous system become big concerns due to the leakage of nanomaterials and possible failure in functionality. To date, it is still challenging to fabricate wearable strain sensors with sensitivity and durability. Herein, we report a simple strategy for large-scale fabrication of core-sheath nanocomposite yarn (CSCY) based wearable sensor with high sensitivity and superior durability. By dispersing aqueous CNT ink into braided composite yarns as the core (BYs-CNT) and electrospun polyurethane (PU) nanofibers as the sheath, a unique core-sheath micro-nanofibrous structure was fabricated to grant the yarn with extremely high sensing sensitivity (maximum GF up to 980), long-term stability and great durability (against washing and dilute hydrochloric acid). The as-developed CSCY strain sensor was demonstrated to monitor real-time subtle and vigorous human activities. The present work provides insights for developing reliable and stable, highly sensitive, flexible and durable wearable electronics with potential applications in different areas. Image 1 [ABSTRACT FROM AUTHOR]

MgFe 2 O 4 /graphene aerogel (MFO/GA) composites were designed and fabricated through a combined electrospinning technique and hydrothermal-induced self-assembly strategy, in which the MFO nanofibers with high crystallinity were wrapped homogeneously and tightly. The as-synthesized MFO/GA composites formed a three-dimensional (3D) conductive network structure with large surface area, high porosity, and high conductivity, which are favorable to accommodate the volume changes of MFO during the repeated lithiation-delithiation processes, shorten the diffusion path, and promote the ions/electrons transfer. As anode material for half-cell, a high reversible capacity of ~1104 mAh g−1 is obtained after 200 cycles at a current density of 0.1 A g−1. Even at 1 A g−1, the MFO/GA delivers a stable capacity of ~686 mAh g−1 over 500 cycles, exhibiting superior rate performance. When assembled with commercial LiCoO 2 cathode to build a full cell system, the MFO/GA anode also can show a reversible capacity of ~714 mAh g−1 after 100 cycles at 0.1 A g−1. The excellent electrochemical performance of MFO/GA in both half and full cells indicates its potential application in practical lithium-ion batteries in the future. Unlabelled Image • MgFe 2 O 4 /graphene aerogel anodes have been facilely prepared by combination of electrospinning and hydrothermal. • MgFe 2 O 4 nanofibers were wrapped in graphene aerogel to form 3D conductive network. • The reversible capacity can reach ~1104 mAh g−1 after 500 cycles in half-cell. • The full cell exhibited a stable capacity of ~714 mAh g−1 after 100 cycles. [ABSTRACT FROM AUTHOR]