Traditional Chemical Reaction Research Articles

Fuel-drivenπ-conjugated Superstructures to Form Transient Conductive Hydrogels.

Despite advances in creating dissipative materials with transient properties, such as hydrogels and active droplets, their application remains confined to temporal changes in structural properties. Developing out-of-equilibrium materials whose electronic functions are parameterized by a chemical reaction cycle is challenging. Yet, this class of materials is required to construct biomimetic materials. In contrast to traditional chemical reaction cycles that exploit molecularly dissolved building blocks at thermodynamic equilibrium, we show that fiber structures derived from reactive naphthalene diimide (NDI) building blocks can be used as resting states to form far-from-equilibrium conductive hydrogels after the addition of chemical fuels. Upon fueling the NDI-derived fibers, a dual-component activation and deactivation pathway is deduced by kinetic analysis and is absent when using a molecularly dissolved resting state. Investigating the solid-state morphologies of the structures formed throughout the fuel-driven reaction cycle using cryo-EM reveals that the resting thermodynamic fibers evolve to transient thicker fibrils and layered superstructures. We show that the transient redox-active hydrogels exhibit a nearly threefold increase in electrical conductivity upon fuel consumption before reverting to their original value over hours. These far-from-equilibrium materials are potential candidates in applications such as programmable biorobotics and chemical computing.

Fuel‐driven π‐conjugated Superstructures to Form Transient Conductive Hydrogels

Despite advances in creating dissipative materials with transient properties, such as hydrogels and active droplets, their application remains confined to temporal changes in structural properties. Developing out‐of‐equilibrium materials whose electronic functions are parameterized by a chemical reaction cycle is challenging. Yet, this class of materials is required to construct biomimetic materials. In contrast to traditional chemical reaction cycles that exploit molecularly dissolved building blocks at thermodynamic equilibrium, we show that fiber structures derived from reactive naphthalene diimide (NDI) building blocks can be used as resting states to form far‐from‐equilibrium conductive hydrogels after the addition of chemical fuels. Upon fueling the NDI‐derived fibers, a dual‐component activation and deactivation pathway is deduced by kinetic analysis and is absent when using a molecularly dissolved resting state. Investigating the solid‐state morphologies of the structures formed throughout the fuel‐driven reaction cycle using cryo‐EM reveals that the resting thermodynamic fibers evolve to transient thicker fibrils and layered superstructures. We show that the transient redox‐active hydrogels exhibit a nearly threefold increase in electrical conductivity upon fuel consumption before reverting to their original value over hours. These far‐from‐equilibrium materials are potential candidates in applications such as programmable biorobotics and chemical computing.

Thermoswitchable catalysis to inhibit and promote plastic flow in vitrimers.

Acid-base catalysis is a common strategy to induce covalent bond exchanges in dynamic polymer networks. Strong acids or strong bases can promote rapid network rearrangements, and are simultaneously preferred catalysts for chemical reactions where maximum efficiency at the lowest possible temperature is aimed for. However, within the context of dynamic polymer networks, the incorporation of highly active catalysts can negatively affect the longer term application potential. Network dynamicity can diminish through catalyst ageing or quenching and highly active catalysts may prematurely activate bond exchanges, leading to dimensional instability and thus low creep resistance of the polymer networks. Herein, we present several examples where we explicitly explored weak acids (carboxylic acids) as catalysts for dynamic bond exchanges, using vinylogous urethanes (VU) as a well-understood protic acid catalysed vitrimer chemistry. Surprisingly, we have found that the sought-after long-term stability offered by a weak acid does not necessarily bring lower activity at high temperature. In fact, the weak acids show a remarkable thermoswitchable catalytic behaviour, going from an inactive hydrogen bonded state to an active state where the polymer matrix is protonated, with a profound impact on the network reactivity and rheology. Carboxylic acids with different electronic or steric environments show clear reactivity trends and their fine-tuning resulted in the most thermally responsive VU vitrimers studied to date. Our findings point out that catalyst choice and design for vitrimers is only poorly informed by catalyst performance in more traditional chemical reactions (in solvent), and that a more tailored catalyst design holds great promise for the field of vitrimers.

Influence analysis of uncertainty of chemical reaction rate under different reentry heights on the plasma sheath and terahertz transmission characteristics

Plasma sheath prediction of hypersonic vehicle is critical to radio frequency (RF) blackout solutions as well as vehicle design and development. In this paper, an optimized chemical reaction (OCR) model by considering the difference in reaction rate coefficient under different re-entry heights is proposed to obtain more accurate plasma sheath distribution. In the OCR model, the correction coefficient of chemical reaction rate at different heights is obtained by deriving the relationship between vehicle surface temperature and reaction rate. Further, through the coupling with hypersonic plasma flow model and co-simulation with terahertz transmission model, the influence of reaction rate uncertainty on the plasma sheath and terahertz transmission characteristics under different heights is studied. The reaction rate uncertainty has little effect on the collision frequency and sheath thickness, but has a significant effect on the electron density. Numerical simulations and comparisons with flight data validate the electron density prediction accuracy of OCR model was improved by more than 13.1% compared with the traditional chemical reaction (TCR) model, which causes prediction accuracy of signal attenuation at 0.05 THz improves about 25%, and it gradually decreases with the increasing terahertz frequency. The above conclusions are of great significance for the communication attenuation prediction and RF blackout schemes.

Research on Application of New Carbon-based Nanomaterials in New Energy Automobile Industry

In order to alleviate the serious impact of over-exploitation of fossil energy such as coal, oil and natural gas, people began to turn their attention to other renewable clean energy sources. Energy storage technology can be roughly divided into two routes: physical energy storage and electrochemical energy storage. Supercapacitor is the most commercial technical device in physical energy storage, which is a good supplement to other electrochemical energy storage technologies. Batteries based on traditional chemical reactions, such as lithium ion, lead acid, Ni-MH, Ni-MH and Ferrous lithium phosphate, have been widely used in many fields. These batteries have large capacity and no memory effect, but their charging and discharging currents are small, their life is short, and their charging circuits are complex. For many occasions with high requirements for reliability, working life and specific power, this kind of battery is slightly insufficient. Therefore, it is imperative to study high-performance energy storage devices. This paper introduces the principle and characteristics of supercapacitors, and analyzes the supercapacitors based on new carbon-based nanomaterials and their applications in the new energy automobile industry.

Flash Synthesis and Continuous Production of C-Arylglycosides in a Flow Electrochemical Reactor

Electrochemistry provides a green and atom-efficient route to synthesize pharmaceutical and useful functional molecules, as it eliminates the need for the harsh chemical oxidants and reductants commonly used in traditional chemical reactions. To promote the implementation of electrochemical processes in the industry, there is a strong demand for the development of technologies that would allow for scale-up and a shortened reaction process time. Herein, we report that electrolysis was successfully accomplished using a flow-divided-electrochemical reactor within a few seconds, enabling the desired chemical conversion in a short period of time. Moreover, the narrow electrode gap of the flow reactor, which offers greener conditions than the conventional batch reactor, resulted in the continuous flash synthesis of C-arylglycosides.

Electrochemical Heteroatom-Heteroatom Bond Construction.

Heteroatom-heteroatom linkage, with S-S bond as a presentative motif, served a crucial role in biochemicals, pharmaceuticals, pesticides, and material sciences. Thus, preparation of the privileged scaffold has always been attracting tremendous attention from the synthetic community. However, classic protocols suffered from several drawbacks, such as toxic and unstable agents, poor functional group tolerance, multiple steps, and explosive oxidizing regents as well as the transitional metal catalysts. Electrochemical organic synthesis exhibited a promising alternative to the traditional chemical reaction due to the sustainable electricity can be employed as the traceless redox agents. Hence, toxic and explosive oxidants and/or transitional metals could be discarded under mild reaction with high efficiency. In this context, a series of electrochemical approaches for the construction of heteroatom-heteroatom bond were reviewed. Notably, most of the cases illustrated the dehydrogenative feature with the clean energy molecules hydrogen as the sole by-product.

Chemical synthesis of micro-nano structure PbBi2S4 under different pressures with the aid of EDTA-2Na

The homologous PbmBi2nXm+3n (X = S, Se, Te) is expected as solar cells or thermoelectric materials. Herein, stable phases of ternary PbBi2S4 microspheres were successfully synthesized by two solution-phase-methods assisting with EDTA-2Na in aqueous media, namely traditional chemical reaction under atmospheric pressure and hydrothermal method under high pressure. Field-emission scanning electron microscopy and X-ray diffraction were used to characterize and determine the morphology and structure of the product. EDTA-2Na plays critical roles in the crystallization process of uniform PbBi2S4 microspheres. A mechanistic model is proposed to account for these experimental findings. Furthermore, the optical band gaps of PbBi2S4 were investigated as well.

Nanozymes with bioorthogonal reaction for intelligence nanorobots.

Bioorthogonal reactions have attained great interest and achievements in various fields since its first appearance in 2003. Compared to traditional chemical reactions, bioorthogonal chemical reactions mediated by transition metals catalysts can occur under physiological conditions in the living system without interfering with or damaging other biochemical events happening simultaneously. The idea of using nanomachines to perform precise and specific tasks in living systems is regarded as the frontier in nanomedicine. Bioorthogonal chemical reactions and nanozymes have provided new potential and strategies for nanomachines used in biomedical fields such as drug release, imaging, and bioengineering. Nanomachines, also called as intelligence nanorobots, based on nanozymes with bioorthogonal reactions show better biocompatibility and water solubility in living systems and perform controlled and adjustable stimuli-triggered response regarding to different physiological environments. In this review, we review the definition and development of bioorthogonal chemical reactions and describe the basic principle of bioorthogonal nanozymes fabrication. We also review several controlled and adjustable stimuli-triggered intelligence nanorobots and their potential in therapeutic and engineered applications. Furthermore, we summarize the challenges in the use of intelligence nanorobots based on nanozymes with bioorthogonal chemical reactions and propose promising vision in smart nanodevices along this appealing avenue of research.

Mechanism of MSWI Fly Ash Solidified by Microbe Cement

Microbe cement, a new type of gelling material, has attracted wide attention due to the increasing awareness of environmental protection. In this paper, the microbe cement in solidifying municipal solid waste incineration (MSWI) fly ash is investigated and the effect of the microbial induction method in solidifying MSWI fly ash is compared with the traditional chemical reaction strategy by characterizing the resulted calcite and the solidification productions with electronic universal testing machine, X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM) and atomic absorption spectrometer. The results show that the MSWI fly ash solidified by microbe cement has the highest compressive strength while that of the chemical CaCO3 products is the lowest. The XRD results show that a new hydration gelling substance (Ca2SiO4·0.30H2O) is generated in the MSWI fly ash products. The FTIR results show that the frequency of Si-O bonds and C-O bonds in the products solidified by microbe cement has shifted, while there is no change occurred in the chemical CaCO3 products. The SEM results show that the microstructure of the products solidified by microbe cement is denser than that of chemical CaCO3 products. The test results of heavy metals show that the microbe cement could reduce the leaching concentration of heavy metals in MSWI fly ash. Ultimately, the leaching concentration of Pb meets the standard requirements, while that of Cd is still slightly higher than the standard requirement.

Mixing enhancement via a serpentine micromixer for real-time activation of carboxyl

Abstract The amide condensation reaction is crucial for preparing biological probes with a polypeptide backbone. The traditional condensation reaction requires the monomer and condensing agent to be pre-mixed and activated by physical agitation mixing, which entail long time, require many reagents, and yield several by-products. In microfluidic mixing devices, the high specific surface area of microchannel enables traditional chemical reactions to be accomplished efficiently and quickly using only trace amounts of reagents in real time. This paper presents a serpentine mixing channel for the activation of amino acid monomers. A number of outward convex elliptical structures are introduced to both sides of the improved serpentine microchannel, creating a Dean vortex that increases the mixing efficiency at low Reynolds condition (90% at Re = 40). Effective monomer activation can be realized directly using a micromixing reactor and leads to less by-products as verified by ultraviolet spectroscopy and high-performance liquid chromatography analysis. The practicability of the micromixer is successfully tested by utilizing it as a microreactor for the real-time activation of amino acids for the in situ synthesis of polypeptide array at a flow rate of 300 μL/min (Re = 40). The proposed micromixer has the potential to be an excellent alternative for conventional flask reactions and integrated in automated miniaturized biochip preparation systems.

Enhancement swelling properties of PVGA hydrogel by alternative radiation crosslinking route

The development of environmentally friendly materials based on non-toxic absorbent polymers, which can ensure high water absorption for several applications in biomedical or agricultural areas, is one of the most complexes problems. In the literature, the non-toxic biodegradable polymer poly(vinyl alcohol) (PVA) was chemically modified with glyoxylic acid to obtain poly(vinylglyoxylic acid) (PVGA) as a biodegradable superabsorbent hydrogel polymer (SHAP), but in fact, the chemical crosslinking reaction decreases the water absorption capacity. In order to crosslink PVGA without losing its absorbent capacity; an alternative radiation-crosslink route has been studied. Radiation-induced crosslinking in the main C-C chain of PVGA where not all free hydrophilic groups (COOH) are involved in a crosslinking reaction as occurs in a traditional chemical reaction. The aim of this work was not only the chemical modification of 99% hydrolyzed PVA to obtain the linear and non-crosslinked PVGA at certain conditions, but also radiation crosslinking at different doses, at dose rate of 5 kGy h−1 attempting to increase the superabsorbent capacity. The samples were characterized by Scanning Electron Microscopy (SEM), Thermo-gravimetrical Analysis (TGA), Nuclear Magnetic Resonance (1H) (NMR) and Infrared Spectroscopy (FTIR). The swelling behavior was measured gravimetrically in different solvents as pure water, buffer pH 3, 7 and 10. Results showed that radiation-crosslink route improves the swelling behavior of PVGA in approximately 215% when compared with PVGA chemically crosslinked, swelled in pure water.

Kinetics of Horseradish Peroxidase-Catalyzed Nitration of Phenol in a Biphasic System.

The use of peroxidase in the nitration of phenols is gaining interest as compared with traditional chemical reactions. We investigated the kinetic characteristics of phenol nitration catalyzed by horseradish peroxidase (HRP) in an aqueous-organic biphasic system using n-butanol as the organic solvent and NO2- and H2O2 as substrates. The reaction rate was mainly controlled by the reaction kinetics in the aqueous phase when appropriate agitation was used to enhance mass transfer in the biphasic system. The initial velocity of the reaction increased with increasing HRP concentration. Additionally, an increase in the substrate concentrations of phenol (0-2 mM in organic phase) or H2O2 (0-0.1 mM in aqueous phase) enhanced the nitration efficiency catalyzed by HRP. In contrast, high concentrations of organic solvent decreased the kinetic parameter Vmax/Km. No inhibition of enzyme activity was observed when the concentrations of phenol and H2O2 were at or below 10 mM and 0.1 mM, respectively. On the basis of the peroxidase catalytic mechanism, a double-substrate ping-pong kinetic model was established. The kinetic parameters were KmH2O2= 1.09 mM, KmPhOH = 9.45 mM, and Vmax = 0.196 mM/min. The proposed model was well fit to the data obtained from additional independent experiments under the suggested optimal synthesis conditions. The kinetic model developed in this paper lays a foundation for further comprehensive study of enzymatic nitration kinetics.

The Progress on Graphene-based Catalysis

Graphene is an atomically thin, two-dimensional allotrope of carbon with excellent chemical, mechanical, and electronic properties. Recent studies have revealed that using graphene or modified graphene as a catalyst support or metal-free catalyst can result in significant improvement in the catalytic activity, selectivity, reusability and tolerance due to the unique structure of graphene. This review summarized the recent progress on the preparation of the graphene-based catalysts and their application in traditional chemical reactions, electrochemical reactions and photochemical catalysis. The perspectives of achieving graphene-based catalysts with high catalytic performance have also been included. Keywords: Catalyst support, graphene-based catalyst, graphene oxide, heterogeneous catalyst, homogeneous catalyst, organic reaction.

Bioinspired Interfaces with Superwettability: From Materials to Chemistry.

Superwettability is a special case of the wetting phenomenon among liquids, gases, and solids. The superhydrophobic/superhydrophilic effect discovered initially has undergone a century of development based on materials science and biomimetics. With the rapid development of research on anti-wetting materials, superoleophobic/superoleophilic surfaces have been fabricated to repel organic liquids besides water. Further studies of underwater superoleophobic/superoleophilic/superaerophobic/superaerophilic materials provide an alternative way to fabricate anti-wetting surfaces rather than lowering the surface energy. Owing to a series of efforts on the studying of extreme wettabilities, a mature superwettability system gradually evolved and has since become a vibrant area of active research, covering topics of superhydrophobicity/superhydrophilicity, superoleophobicity/superoleophilicity in gas or under liquid, superaerophobicity/superaerophilicity under liquid, and combinations of these states. The kinetic study of the superwettability system includes statics and dynamics, while the studied material structures range from traditional two-dimensional materials to three-dimensional, one-dimensional, and zero-dimensional materials. Furthermore, the wetting liquids range from water to oil, aqueous solutions, and ionic liquids, as well as liquid crystals and other types of liquids. The wetting conditions extend over a wide range of temperatures, pressures, and other external fields. With the development of this series of research, many new theories and functional interfacial materials have been fabricated, including self-cleaning textiles, oil/water separation systems, and water collection systems, and some of these have already been applied in industry. Moreover, the study of superwettability has also introduced many new phenomena and principles to the field of interfacial chemistry that display its vast potential in both materials and chemistry. The present Perspective aims to summarize the most recent research on these materials and their interfacial chemistry. An overview of novel materials in superwettability systems and interfacial materials is presented. Specifically, the evolution of superwettable materials will be introduced, and the fundamental rules for building these superwetting materials will be discussed, followed by a summary of recent progress in the application of superwettable materials to alter the behaviors of chemical reactants and products. Specific emphasis is placed on recent strategies that exploit superwettable materials to influence the performance of traditional chemical reactions and their unique contributions to chemistry, including the effective collection of reaction products, unique growth models of precipitates, and a simple strategy for the alignment/assembly of nanoscale building blocks. Finally, a short perspective is provided on the potential for future developments in the field.

Chemical reaction engineering in the chemical processing of metals and inorganic materials

In traditional chemical reaction engineering, it is possible to incorporate only the simplified aspects of fluid flow, mixing, and mass/heat transfer into the analysis of chemical reaction rates and reactor design. As a consequence of the advent of high-speed, high-capacity computing capacity, complex processes involving chemical reactions have become amenable to analysis and modeling. This has also resulted in the merging of various disciplines of chemical engineering in formulating detailed descriptions of complex processes. Developments that exemplify this trend over the years are discussed in this review. Several examples from the author’s previous work are used to illustrate the application of chemical reaction engineering principles to the modeling and analysis of complex systems involving the chemical processing of metals and other inorganic materials.