Additive-free synthesis of S-substituted isothioureas via visible-light-induced four-component reaction ofα-diazoesters,aryl isothiocyanates,amines and cyclic ethers

An additive-free and environmentally friendly strategy has been realized for the construction of S-substituted isothioureas through visible-light-induced multicomponent reaction starting fromα-diazoesters,aryl isothiocyanates,amines and cyclic ethers.This methodology features simple operation,mild reaction conditions,favorable functional group tolerance,easily available starting materials and high efficiency.

Size effect enabling additive-free MXene ink with ultrahigh conductivity for screen printing of wireless electronics

Facile preparation of additive-free inks with both high viscosity and high conductivity is critical for scalable screen printing of wireless electronics,yet very challenging.MXene materials exhibit excellent conductivity and hydrophilicity,showing great potential in the field of additive-free inks for screen printing.Here,we demonstrate the synthesis of additive-free two-dimensional(2D)titanium carbide MXene inks,and realize screen-printed MXene wireless electronics for the first time.The viscosity of MXene ink is solely regulated by tuning the size of MXene nanosheet without any additives,hence rendering the printed MXene film extremely high conductivity of 1.67×10^(5) S/m and fine printing resolution down to 0.05 mm on various flexible substrates.Moreover,radio frequency identification(RFID)tags fabricated using the additive-free MXene ink via screen printing exhibit stable antenna reading performance and superb flexibility.This article,thus offers a new route for the efficient,low-cost and pollution-free manufacture of printable electronics based on additive-free MXene inks.

Solvent additive-free ternary polymer solar cells with 16.27% efficiency

Ternary strategy has been commonly demonstrated as an efficient method to improve the performance of polymer solar cells(PSCs), which has great potential in application of PSCs due to the simple device fabrication.

Additive-free porous assemblies of Ti3C2Tx by freeze-drying for high performance supercapacitors

Ti3C2Tx has shown great potential in energy storage filed,but the restacking between Ti3C2Tx nanosheets seriously hampers the maximization of its capacitance.In this study,we rationally designed and synthesized porous Ti3C2Tx assemblies without any additive by introducing ice as spacers using a facile freeze-drying method.The porous Ti3C2Tx assemblies have a three-dimensional network structure,which consists of ultra large Ti3C2Tx lamellar walls and lots of macro-and mesopores.It has been proven that there are more-O groups on the surface of the porous Ti3C2Tx assemblies than the Ti3C2Tx film.The porous Ti3C2Tx assemblies deliver a maximum areal capacitance of 1668 mF/cm^2 when the mass loading is 8.4 mg/cm^2,an optimized specific capacitance of 247.2 F/g when the mass loading is 5.3 mg/cm^2,and87%capacitance retention over 10000 cycles.The symmetric solid-state supercapacitors based on the porous Ti3C2Tx assemblies show an areal capacitance of 355.8 mF/cm^2,the maximum power density of50 mW/cm^2 and an outstanding flexibility under different deformation.

Effect of process parameters on additive-free electrospinning of regenerated silk fibroin nonwovens

Silk fibroin is a biomaterial with multiple beneficial properties for use in regenerative medicine and tissue engineering.When dissolving and processing the reconstituted silk fibroin solution by electrospinning,the arrangement and size of fibers can be manifold varied and according fiber diameters reduced to the nanometer range.Such nonwovens show high porosity as well as potential biocompatibility.Usually,electrospinning of most biomaterials demands for the application of additives,which enable stable electrospinning by adjusting viscosity,and are intended to evaporate during processing or to be washed out afterwards.However,the use of such additives increases costs and has to be taken into account in terms of biological risks when used for biomedical applications.In this study,we explored the possibilities of additive-free electrospinning of pure fibroin nonwovens and tried to optimize process parameters to enable stable processing.We used natural silk derived from the mulberry silkworm Bombyx mori.After degumming,the silk fibroin was dissolved and the viscosity of the spinning solution was controlled by partial evaporation of the initial solving agent.This way,we were able to completely avoid the use of additives and manufacture nonwovens,which potentially offer higher biocompatibility and reduced immunogenicity.Temperature and relative humidity during electrospinning were systematically varied(25–35°C,25–30%RH).In a second step,the nonwovens optionally underwent methanol treatment to initiate beta-sheet formation in order to increase structural integrity and strength.Comprehensive surface analysis on the different nonwovens was performed using scanning electron microscopy and supplemented by additional mechanical testing.Cytotoxicity was evaluated using BrdU-assay,XTT-assay,LDH-assay and live-dead staining.Our findings were,that an increase of temperature and relative humidity led to unequal fiber diameters and defective nonwovens.Resistance to penetration decreased accordingly.The most uniform fiber diameters of 998±63 nm were obtained at 30°C and 25%relative humidity,also showing the highest value for resistance to penetration(0.20 N).The according pure fibroin nonwoven also showed no signs of cytotoxicity.However,while the biological response showed statistical evidence,the material characteristics showed no statistically significant correlation to changes of the ambient conditions within the investigated ranges.We suggest that further experiments should explore additional ranges for temperature and humidity and further focus on the repeatability of material properties in dependency of suitable process windows.

Study of Effective Electrical Conductivity of Additive Free Electrodes Using a Homogenization Method

Conductive additives are used in the cathode of a Li-ion battery to improve electrical conductivity.However,these additives can negatively impact the ionic conductivity and specific capacity of the battery.Therefore,design of additive-free cathodes is gaining attention in the research community.In this paper,we explore the effective electrical conductivity of randomly generated two-phase conductive-free cathode microstructures using a mathematical homogenization method.Over thousand microstructures with various combinations of particle size,volume fraction and conductivity ratios are considered to evaluate effective electrical conductivity values using this method.An explicit formulation is proposed based on the results to provide a simple method for evaluation of the effective conductivity values.The intrinsic properties of each phase of the microstructure are used to obtain the effective electrical conductivity values.With the microstructure geometry information being utilized for the evaluation of the effective properties,the results obtained from this formulation are expected to be more accurate and reliable than those obtained using the popular Bruggeman’s approximation,providing better estimates of discharge characteristics.Finally,the significance of incorporation of micro-structural information to model cathodes is highlighted by studying the discharge characteristics of Li-ion battery system.

Revealing efficient catalytic performance of N-CuO_(x) for aerobic oxidative coupling of aliphatic alkynes:A Langmuir-Hinshelwood reaction mechanism

O_(x)idative couplings of aliphatic alkynes are crucial for the production of naturally occurring 1,3-diynes.Herein we report the novel approach for effective synthesis of unsaturated coordinated N doped copper oxides(N-CuO_(x))catalyst,and uncover that N-CuO_(x) catalyst as an additive-free and cost-effective heterogeneous catalyst has highly catalytic performance for directly oxidative coupling of aliphatic alkynes.The key to achieve efficient oxidative coupling of aliphatic alkynes is the synergistic effect of N species and uncoordinated O/Cu species caused by N dopants,which undergoes the Langmuir–Hinshelwood reaction mechanism.The N-CuO_(x) catalyst displays~89.1%yield for hexadeca-7,9-diyne under mild conditions and stable reusability(5 cycles),showing significant advances compared with the traditionally copper oxides.These findings highlight the heteroatom dopants that provide a new methodology for designing efficient copper catalysts in synthesis of naturally occurring 1,3-diynes.

Glycopeptide ligation via direct aminolysis of selenoester

Direct aminolysis of selenoester in aqueous media was investigated as a glycopeptide ligation strategy.This strategy allows the peptide and glycopeptide ligation to proceed smoothly(even with hindered amino acids) without the need of cysteine residue, N-terminal thiol auxiliary or coupling additive, and to afford the corresponding amide products in excellent yields. No epimerization was observed during ligation reations. In this work, the selenoester of unprotected glycopeptide was readily prepared, and the direct aminolysis of glycopeptide selenoester was successfully applied to synthesize MUC1 mucin sequence efficiently.

Wearable Fiber‑Based Supercapacitors Enabled by Additive‑Free Aqueous MXene Inks for Self‑Powering Healthcare Sensors

Wearable fiber-based electronics have found diverse applications including energy storage,healthcare or thermal management,etc.In particular,additive-free aqueous inks play significant roles in fabrication of wearable fiber-based devices,owning to their nontoxic nature and ease of manufacturing.Herein,wearable carbon fiber-based asymmetric supercapacitors(WASSC)are developed based on additive-free aqueous MXene inks,for self-powering healthcare sensors.The sediments of MXene without further modification are used as inks.Furthermore,combined with additive-free aqueous MXene/polyaniline(MP)inks,WASSC,with a wide voltage window and high capacitance is developed for practical energy supply.Impressively,WASSC has been successfully utilized to power wearable pressure sensors that could monitor motions and pulse signals.This wearable self-powered monitoring system on can accurately monitor the human motions,pronunciation,swallow or wrist pulse,without using the rigid batteries.This advantage realizes a great potential in simple and cost effective monitoring of human health and activities.Besides,self-powered system enables waste recycling of MXene and provides an effective approach for designing wearable and fiber-based self-powered sensors.