Self-Healable Polyelectrolytes with Mechanical Enhancement for Flexible and Durable Supercapacitors

The practical application of advanced personalized electronics is inseparable from flexible, durable, and even self-healable energy storage devices. However, the mechanical and self-healing performance of supercapacitors is still limited at present. Herein, highly transparent, stretchable, and self-healable poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA)/poly(vinyl alcohol) (PVA)/LiCl polyelectrolytes were facilely prepared by one-step radical polymerization. The cooperation of PAMPSA and PVA significantly increased the mechanical and self-healing capacity of the polyelectrolyte, which exhibited superior stretchability of 938 %, stress of 112.68 kPa, good electrical performance (ionic conductivity up to 20.6 mS cm⁻¹), and high healing efficiency of 92.68 % after 24 h. After assembly with polypyrrole-coated single-walled carbon nanotubes, the resulting as-prepared supercapacitor had excellent electrochemical properties with high areal capacitance of 297 mF cm⁻² at 0.5 mA cm⁻² and good rate capability (218 mF cm⁻² at 5 mA cm⁻²). Besides, after cutting in two the supercapacitor recovered 99.2 % of its original specific capacitance after healing for 24 h at room temperature. The results also showed negligible change in the interior contact resistance of the supercapacitor after ten cutting/healing cycles. The present work provides a possible solution for the development of smart and durable energy storage devices with low cost for next-generation intelligent electronics.     

Acetate chitosan with CaCO3 doping form tough hydrogel for hemostasis and wound healing

In recent years, chitosan has been applied for wound management due to its properties of biocompatibility, biodegradability, antimicrobial activity, and low immunogenicity. But the poor water solubility in neutral pH limited its further application in clinical wound healing. To overcome this problem, acetate chitosan was developed and approved as commercial products for wound healing. However, the acidity of acetate chitosan was potentially allergenic, and the poor mechanical properties of its formed hydrogels also hindered the therapeutic efficacy in wound care. In this study, CaCO₃ was simply doped into acetate chitosan to form the wound dressing. After absorbing water, the H⁺ of acetate chitosan reacted with CaCO₃ to release Ca²⁺, resulting in acidity decreased. The production of Ca²⁺ and residue of CaCO₃ cross‐linked with chitosan to form a tough hydrogel by electrostatic interaction. The physical characteristics, swelling, mechanical testing, and blood clotting were evaluated. The results in vitro demonstrated that after doping CaCO₃ into acetate chitosan, the mechanical properties and blood clotting of the formed hydrogel were increased. Then, the evaluation of hydrogels in vivo revealed that it can also accelerate the wound healing by promoting re‐epithelization and collagen deposition. This simple way by doping CaCO₃ into acetate chitosan can increase wound healing, and it can also broad the application of acetate chitosan in clinical use.     

Highly Efficient and Diastereoselective Construction of Tricyclic Pyrrolidine‐Fused Benzo[b]thiophene 1,1‐dioxide Derivatives via 1,3‐Dipolar [3 + 2] Cycloaddition

A rapid and highly efficient 1,3‐dipolar [3 + 2] cycloaddition of nonstabilized azomethine ylides generated in situ with benzo[b]thiophene 1,1‐dioxides as the dipolarophiles has been developed. The efficient method affords tricyclic pyrrolidine‐fused benzo[b]thiophene 1,1‐dioxide derivatives in high to excellent yields (up to 99%) with excellent diastereoselectivities (up to >25:1 dr) under mild reaction conditions. The structure of a typical product was confirmed by X‐ray crystallography.     

Preparation of stable and superior flux GO/LDH/PDA‐based nanofiltration membranes through electrostatic self‐assembly for dye purification

Graphene oxide (GO) has triggered significant attention as a new type of self‐assembly membrane material. However, the low filtration flux and unstable performance of GO membrane limit its practical application. Hence, in this work, layered double hydroxides (LDHs), as a 2D material with double‐layer channel structure and positive electricity, were self‐assembled with GO at weight ratio of 7:3 by electrostatic interaction. Then, the GO/LDH hybrids combined with polydopamine (PDA) to obtain stable and high‐flux GO‐based membranes through vacuum filtration and the structure and morphology of as‐prepared samples were characterized by FT‐IR, XRD, XPS, and SEM. Furthermore, the separation performance and surface electronegativity of membranes were tested via pure water flux, rejection efficiency, recycle experiments, and zeta potential. Results revealed that the stability and flux of composite membrane were enhanced significantly compared with neat GO‐based membrane. Further, the dye rejection rate of methylene blue (MB) is higher than Congo red (CR) and rhodamine B (Rh B) and reached to 99.8%.     

Bare polyprolylene hollow fiber as extractive phase for in‐tube solid‐phase microextraction to determine estrogens in water samples

Polypropylene hollow fibers as the adsorbent were directly filled into a polyetheretherketone tube for in‐tube solid‐phase microextraction. The surface properties of hollow fibers were characterized by a scanning electron microscope. Combined with high performance liquid chromatography, the extraction tube showed good extraction performance for five environmental estrogen hormones. To achieve high analytical sensitivity, four important factors containing sampling volume, sampling rate, content of organic solvent in sample, and desorption time were investigated. Under the optimum conditions, an online analysis method was established with wide linear range (0.03–20 µg/L), good correlation coefficients (≥0.9998), low limits of detection (0.01–0.05 µg/L), low limits of quantitation (0.03–0.16 µg/L), and high enrichment factors (1087–2738). Relative standard deviations (n = 3) for intraday (≤3.6%) and interday (≤5.1%) tests proved the stable extraction performance of the material. Durability and chemical stability of the extraction tube were also investigated, relative standard deviations of all analytes were less than 5.8% (n = 3), demonstrating the satisfactory stability. Finally, the method was successfully applied to detect estrogens in real samples.     

Carbonized cotton fibers via a facile method for highly sensitive solid‐phase microextraction of polycyclic aromatic hydrocarbons

Cotton fiber is an environmentally friendly and natural material with a certain extraction capacity, while its enrichment ability is poor. In order to improve the extraction efficiency of cotton fibers, it was carbonized to form a layer of amorphous carbon as the sorbent by a simple carbonization method. Carbonized cotton fibers were filled into a polyetheretherketone tube for in‐tube solid‐phase microextraction. The carbonization time was investigated to obtain high extraction efficiency. Coupled to high‐performance liquid chromatography, the extraction tube was evaluated with polycyclic aromatic hydrocarbons, estrogens and phthalates, and it exhibited best extraction efficiency for polycyclic aromatic hydrocarbons. Under the optimum conditions, an online analysis method for several polycyclic aromatic hydrocarbons was established with large linear ranges (0.016–0.20 μg/L), low limits of detection (0.005–0.020 μg/L), and high enrichment factors (948–2874). Analysis method was successfully applied to the detection of targets in the real samples and shown satisfactory durability and chemical stability. Moreover, the relative recoveries ranged from 82 to 119.2%, which demonstrated the applicability of carbonized cotton fibers in sample preparation. Compared with other reported methods, the proposed method provided shorter extraction time, higher enrichment factors, comparable limits of detection, and recoveries.     

Styrene‐N‐phenylacrylamide co‐polymer modified silica monolith particles with an optimized mixing ratio of monomers as a new stationary phase for the separation of peptides in high performance liquid chromatography

A stationary phase was prepared by chemical derivatization of the support particles with a layer of copolymer composed of styrene and N‐phenyl acrylamide. Silica monolith particles of ca. 2.6 µm (volume‐based average) have been prepared as the support particles by sol‐gel reaction followed by differential sedimentation. The particles were reacted with 3‐chloropropyl trimethoxysilane followed by sodium diethyldithiocarbamate to introduce an initiator moiety. Then, the copolymer layer was immobilized via reversible addition‐fragmentation transfer polymerization. The resultant phase was packed in glass‐lined stainless‐steel micro‐columns (1 x 150 mm) and evaluated for the separation of a mixture composed of five peptides (Trp‐Gly, Thr‐Tyr‐Ser, angiotensin I, isotocin and bradykinin). The effect of monomer mixing ratio (styrene versus N‐phenyl acrylamide) on the chromatographic separation efficiency of the stationary phase was examined. A number of theoretical plates (N) as high as 33 600 plates/column (224 000 plates/m, 4.46 µm plate height) was achieved using the column packed with the optimized stationary phase. The column‐to‐column reproducibility based on three columns packed with three different batches of stationary phase was found satisfactory in separation efficiency, retention factor, and asymmetry factor.     

Exploration and optimization of conditions for quantitative analysis of lignans in Schisandra chinensis by an online supercritical fluid extraction with supercritical fluid chromatography system

An online supercritical fluid extraction with supercritical fluid chromatography system could provide sequential extraction and quantitative analysis of lignans in Schisandra chinensis. Supercritical fluid extraction conditions were optimized at 15 MPa, 50°C, and 4 min with supercritical CO₂ adding 1% methanol; the elution volume and flow rate were set at 6 mL and 2 mL/min to blow extract out of the tank completely. The split‐flow rate was confirmed at 2.5%, which determines injection volume and accuracy of quantitative detection. The factors having negative influences on supercritical fluid chromatography retention in the online system, including sample loading forms and backpressure settings, are discussed in the paper. At last, an extraction‐quantitative method for lignans in Schisandra chinensis was developed, which could be finished within 19.5 min. The total content percentage of four lignans (Schisandrin, Schisandrin A, Schisandrin B and Schisandrol B) in four batches was respectively measured to be 1.42, 1.54, 1.62, and 1.90%.     

Nano‐MoO3 for highly selective enrichment of polycyclic aromatic hydrocarbons in in‐tube solid‐phase microextraction

Nano‐molybdenum trioxide was prepared from nano‐molybdenum disulfide by simple firing in muffle furnace. Nano‐molybdenum trioxide was used as the extraction coating on the stainless steel wire. Four wires were filled in a polyetheretherketone tube to get an extraction tube. The tube was connected to the six‐port valve of a high performance liquid chromatograph, and the online analysis system was constructed. Extraction selectivity of the tube for different types of compounds, including polycyclic aromatic hydrocarbons, plasticizers, estrogens, anilines and neonicotinoids, was studied. Good enrichment ability for polycyclic aromatic hydrocarbons, but the extraction efficiency of others was not satisfactory. Using eight polycyclic aromatic hydrocarbons as the targets, an analytical method was established after optimizing main factors such as sampling volume, sampling rate, methanol content, and desorption time. The established method exhibited wide linear range to 0.016–20.00 μg/L and low limits of detection to 0.005 μg/L, and the enrichment factors can be up to 2443. The method was applied to the detection of trace polycyclic aromatic hydrocarbons in tap water and river water, and a good recovery was obtained. The tube showed good durability and chemical stability, and it still remained good extraction effect after more than 140 run.     

An optimized mixed‐mode stationary phase based on silica monolith particles for the separation of peptides and proteins in high‐performance liquid chromatography

A phase with both hydrophobic and hydrophilic functionalities has been synthesized by modification of ground silica monolith particles with C18 and 1‐[3‐(trimethoxysilyl)propyl] urea ligands. A series of phases was prepared by changing the ratio of the two ligands to determine the optimal ratio in view of separation efficiency. The resultant optimized stationary phase was packed in narrow‐bore glass‐lined stainless‐steel columns (1 × 300 mm and 2.1 × 100 mm) and used for the separation of synthetic peptides and proteins. The average numbers of theoretical plates (N) of 52 100/column (174 000/m, 5.75 µm plate height) and 35 500/column (118 000/m, 8.47 µm plate height) were achieved with the 300 mm column at a flow rate of 25 µL/min (0.86 mm/s) in 60:40 v/v acetonitrile/30 mM aqueous ammonium formate for the mixture of peptides (Thr‐Tyr‐Ser, Val‐Ala‐Pro‐Gly, angiotensin I, isotocin, and bradykinin) and for the mixture of proteins (myoglobin, human serum albumin, and insulin), respectively. Fast analysis of the peptides and proteins was also carried out at a flow rate of 0.9 mL/min (6.88 mm/s) with the 100 mm column and all the analytes were eluted within 2 min with good separation efficiency.