A stretchable carbon nanotube (CNT) fiber based wire‐shaped supercapacitor is fabricated using a prestraining‐then‐buckling approach. At tensile strains from 0% to 100% or after 20 mechanical ...stretching‐releasing cycles with maximum strain of 100%, the electrochemical properties are not reduced but rather somewhat improved. This may have implications for the integration of wire‐shaped supercapacitors with wearable, miniaturized, and portable electronic devices.
Due to their exceptional flexibility and transparency, CVD graphene films have been regarded as an ideal replacement of indium tin oxide for transparent electrodes, especially in applications where ...electronic devices may be subjected to large tensile strain. However, the search for a desirable combination of stretchability and electrochemical performance of such devices remains a huge challenge. Here, we demonstrate the implementation of a laminated ultrathin CVD graphene film as a stretchable and transparent electrode for supercapacitors. Transferred and buckled on PDMS substrates by a prestraininig-then-buckling strategy, the four-layer graphene film maintained its outstanding quality, as evidenced by Raman spectra. Optical transmittance of up to 72.9% at a wavelength of 550 nm and stretchability of 40% were achieved. As the tensile strain increased up to 40%, the specific capacitance showed no degradation and even increased slightly. Furthermore, the supercapacitor demonstrated excellent frequency capability with small time constants under stretching.
Cotton fabric has a wide application due to its hygroscopicity, air permeability, and large production of cotton fiber used to make the fabric. However, cotton materials are a safety hazard during ...its application because of flammability (limiting oxygen index is about 18%). In order to improve the flame retardancy of cotton fibers and reduce the damage of its mechanical properties, novel P/Si based flame retardant (PFR) nanoparticles were synthesized by one-step radical polymerization. Vinyl phosphoric acid and tetramethyl divinyl disiloxane were introduced into the nanoparticles. The structure, morphology and thermal stability of PFR was characterized by fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis test (TGA). Durable flame retardant cotton fibers were prepared by dip-coating and plasma induced crosslinking methods. Micro-calorimeter (MCC) characterization showed that the peak of heat release rate (pHRR) and the total heat release (THR) were reduced by 47.3% and 29.8% for modified cotton fibers compared with pure cotton fibers. Limiting oxygen index (LOI) of modified cotton fibers was increased to 27%. The residue carbon of modified cotton fibers was 19.0% at 700 °C, while the value of pure cotton fibers was 3.0%. Besides, durability of the modified cotton fibers was approved by cyclic washing test. In addition, flame retardant mechanism was revealed by collecting and analyzing condensed and gaseous pyrolysis products. The data of FE-SEM for residue carbon, FT-IR spectra of products at different pyrolysis temperatures and pyrolysis gas chromatography mass spectrometry (Py-GC–MS) showed that PFR was a synergistic flame retardant contained barrier and quenching effecting applied on cotton materials.
Graphical abstract
Novel phosphorus-silicon based nanoparticles were synthesized by one-step radical polymerization and applied to improve the flame retardant of cotton materials by dip-coating and plasma induced crosslinking.
In this article, biodegradable poly(butylene succinate-co-butylene terephthalate) (PBST) copolyesters with high molecular weights were synthesized by direct esterification and polycondensation route. ...The reaction conditions and catalytic systems were investigated in detail. Through balancing the reaction efficiency and the costs of reactants, the proper molar ratio of diol to diacid was determined. Titanium tetraisopropoxide (TTiPO) was found to be an effective catalyst both in esterification and polycondensation reaction, and its content was optimized based on the esterification ratio and amount of formed by-products. The complex reaction was determined to be the dominant catalytic reaction mechanism. By importing the additives of metal oxides coupled with TTiPO, the weight-average molecular weights of PBST increased sharply from 8.51 x 10⁴ to 14.38 x 10⁴, manifesting the additives promoted the polymerization reaction greatly. The enhancement of carbonyl polarization and provision of suitable reaction space arose from the metal oxides were the reasons for promoting the polymerization reaction. With respect to thermal properties, the same melting point and heat of fusion were found, while thermal stability increased with the import of additives. The result was prone to be interpreted by the higher molecular weights of PBST in the presence of additives.
The dilemma of diminishing freshwater resources caused by water pollution has always impacted human life. Solar-driven interfacial evaporation technology has the potential for freshwater production ...via solar-driven distillation. However, in solar-driven interfacial evaporation technology, it is difficult to overcome the problem of wastewater containing various contaminants. In this work, we propose a bifunctional fabric created by depositing titanium dioxide@carbon black nanoparticles onto cotton fabric (TiO2@CB/CF). The TiO2@CB/CF has a coupling effect that includes the photothermal effect of CB and photocatalysis of TiO2, and it can not only generate clean water but can also purify contaminated water. The resulting bifunctional fabric can achieve an outstanding water evaporation rate of 1.42 kg m−2 h−1 and a conversion efficiency of 90.4% in methylene blue (MB) solution under one-sun irradiation. Simultaneously, the TiO2@CB/CF demonstrates a high photocatalytic degradation of 57% for MB solution after 2 h with light irradiation. It still shows a good photocatalysis effect, even when reused in an MB solution for eight cycles. Furthermore, the TiO2@CB/CF delivers excellent performance for actual industrial textile dyeing wastewater. This bifunctional fabric has a good application prospect and will provide a novel way to resolve the issue of freshwater scarcity.
•HECs with low molar substitution (MS) values were prepared as expected.•The changes of structure and property of HECs were explored intensively with the rising MS value.•HECs with the MS value of ...0.17–0.3 are suitable to fabricate regenerated cellulose products.•HECs with the MS value more than 0.3 have great potential to serve as absorbent materials.
Hydroxyethyl celluloses (HECs) with low molar substitutions (MS) were prepared by reaction of alkali cellulose with ethylene oxide (EO) in a heterogeneous process. NMR, FTIR, WAXD, TG, solubility and tensile tests were adopted to investigate the changes of structures and properties of HECs with their MS values. NMR results showed that the hydroxyethyl groups were introduced into the cellulose chains as expected, causing the destruction in ordered structure and a loss in crystallinity. Crystal transformation from cellulose I of raw cellulose to cellulose II of HECs was proved by different methods. The crystalline structure of HEC seriously deteriorated with the rising MS value, accompanying lower thermal stability and improvements on its solubility in 8 wt% NaOH solvent and moisture related properties such as water retention. These different properties depending on the MS values endowed HECs with various potential applications in the form of regenerated cellulose fibers or other absorbent materials.
•Hydroxyethyl groups were introduced to cellulose chains for improving its solubility.•NaOH complex solution was applied to obtain spinning solutions of high quality.•Stable spinning solutions with ...5–13wt% concentration were successfully prepared.•Structural changes from cellulose to regenerated HEC fibers were studied.•The prepared HEC fibers had good mechanical properties comparable to viscose fibers.
Novel spinning solution, prepared by dissolving hydroxyethyl cellulose (HEC) owning a low molar substitution (MS) into NaOH/urea/thiouea aqueous solution with a specific weight ratio of 8:8:6.5, was employed to fabricate a new type of regenerated fibers by wet-spun method. The structure and properties of the resultant HEC fibers were characterized by 13C NMR, FTIR, synchrotron WAXS, SEM, and tensile tester. The results showed that HEC fibers exhibited structure identical with HEC because of the physical dissolution and coagulation processes, but quite different from native cellulose due to partial breakage of hydrogen bonds and crystal transformation from cellulose I to cellulose II during cellulose modification. The resultant HEC fibers with relatively dense and homogenous structure displayed good moisture related properties and stayed stable in alkali solution with low concentration. Moreover, the novel fibers owned good dry mechanical properties in spit of their slightly poor wet mechanical properties comparable to viscose rayon, showing great potential in substituting the traditional viscose fibers.
Immediate hemorrhage control and anti-infection play important roles in the wound management. Besides, a moist environment is also beneficial for wound healing. Hydrogels are promising materials in ...urgent hemostasis and drug release. However, hydrogels have the disadvantage of rapid release profiles, leading to the exposure to high drug concentrations. In this study, we constructed hybrid hydrogels with rapid hemostasis and sustainable antibacterial property combining aminoethyl methacrylate hyaluronic acid (HA-AEMA) and methacrylated methoxy polyethylene glycol (mPEG-MA) hybrid hydrogels and chlorhexidine diacetate (CHX)-loaded nanogels. The CHX-loaded nanogels (CLNs) were prepared by the enzyme degradation of CHX-loaded lysine-based hydrogels. The HA-AEMA and mPEG-MA hybrid hydrogel loaded with CLNs (labeled as Gel@CLN) displayed a three-dimensional microporous structure and exhibited excellent swelling, mechanical property, and low cytotoxicity. The Gel@CLN hydrogel showed a prolonged release period of CHX over 240 h and the antibacterial property over 10 days. The hemostasis and wound-healing properties were evaluated in vivo using a mouse model. The results showed that hydrogel had the rapid hemostasis capacity and accelerated wound healing. In summary, CLN-loaded hydrogels may be excellent candidates as hemostasis and anti-infection materials for the wound dressing application.
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