An efficient microreactor with continuous serially connected micromixers for the synthesis of superparamagnetic magnetite nanoparticles

A new microreactor with continuous serially connected micromixers(CSCM)was tailored for the coprecipitation process to synthesize Fe_(3)O_(4) nanoparticles.Numerical simulation reveals that the two types of CSCM microchannels(V-typed and U-typed)proposed in this work exhibited markedly better mixing performances than the Zigzag and capillary microchannels due to the promotion of Dean vortices.Complete mixing was achieved in the V-typed microchannel in 2.7 s at an inlet Reynolds number of 27.Fe_(3)O_(4) nanoparticles synthesized in a planar glass microreactor with the V-typed microchannel,possessing an average size of 9.3 nm and exhibiting superparamagnetism,had obviously better dispersity and uniformity and higher crystallinity than those obtained in the capillary microreactor.The new CSCM microreactor developed in this work can act as a potent device to intensify the synthesis of similar inorganic nanoparticles via multistep chemical precipitation processes.

Heteroatom-doped porous carbon from methyl orange dye wastewater for oxygen reduction

Banana peel-derived porous carbon(BPPC) was prepared from banana peel and used as an adsorbent for methyl orange(MO) wastewater removal. BPPC-MO50 is a N,S-doped BPPC obtained via secondary carbonization. The BPPC-MO50 exhibited a high specific surface area of1774.3 m^2/g. Heteroatom-doped porous carbon(PC) was successfully synthesized from the BPPC absorbed MO at high temperature and used for oxygen reduction. The BPPC-MO50 displayed the highest ORR onset potential among all carbon-based electrocatalysts, i.e., 0.93 V vs.reversible hydrogen electrode(RHE). This is the first report to describe porous carbon-activated materials from agriculture and forestry waste that is used for adsorption of dyes from wastewater via an enhanced heteroatom(N,S) content. These results may contribute to the sustainable development of dye wastewater treatment by transforming saturated PC into an effective material and has potential applications in fuel cells or as energy sources.

Oxygen vacancies enriched nickel cobalt based nanoflower cathodes: Mechanism and application of the enhanced energy storage

The rational design of oxygen vacancies and electronic microstructures of electrode materials for energy storage devices still remains a challenge. Herein, we synthesize nickel cobalt-based oxides nanoflower arrays assembled with nanowires grown on Ni foam via the hydrothermal process followed annealing process in air and argon atmospheres respectively. It is found that the annealing atmosphere has a vital influence on the oxygen vacancies and electronic microstructures of resulting NiCo_(2)O_(4) (NCO-Air) and CoNiO_(2) (NCO-Ar) products, which NCO-Ar has more oxygen vacancies and larger specific surface area of 163.48 m^(2)/g. The density functional theory calculation reveals that more oxygen vacancies can provide more electrons to adsorb –OH free anions resulting in superior electrochemical energy storage performance. Therefore, the assembled asymmetric supercapacitor of NCO-Ar//active carbon delivers an excellent energy density of 112.52 Wh/kg at a power density of 558.73 W/kg and the fabricated NCO-Ar//Zn battery presents the specific capacity of 180.20 mAh/g and energy density of 308.14 Wh/kg. The experimental measurement and theoretical calculation not only provide a facile strategy to construct flower-like mesoporous architectures with massive oxygen vacancies, but also demonstrate that NCO-Ar is an ideal electrode material for the next generation of energy storage devices.

High efficient oxygen reduction performance of Fe/Fe3C nanoparticles in situ encapsulated in nitrogen-doped carbon via a novel microwave-assisted carbon bath method

Fe-based carbon materials are widely considered promising to replace Pt/C as next-generation electrocatalysts towards oxygen reduction reaction (ORR). However, the preparation of Fe-based carbon materials is still carried out by conventional heating method (CHM). Herein, a novel microwave-assisted carbon bath method (MW-CBM) was proposed, which only took 35 min to synthesize Fe/Fe3C nanoparticles encapsulated in N-doped carbon layers derived from Prussian blue (PB). The catalyst contained large specific surface area and mesoporous structure, abundant Fe-Nx and C–N active sites, unique core-shell structure. Due to the synergistic effects of these features, the as-prepared Fe/Fe3C@NC-2 displayed outstanding ORR activity with onset potential of 0.98 VRHE and halfwave potential of 0.87 VRHE, which were more positive than 20 wt.% Pt/C (0.93 VRHE and 0.82 VRHE). Besides, Fe/Fe3C@NC-2 gave a better stability and methanol tolerance than Pt/C towards ORR in alkaline media, too.

Pod-Like Supramicelles with Multicompartment Hydrophobic Cores Prepared by Self-Assembly of Modified Chitosan

In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by selfassembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam)(PHCS-g-PNVCL) in aqueous medium. The employed biocompatible amphiphilic polymer was synthesized by grafting the carboxyl terminated poly(N-vinylcaprolactam)(PNVCL-COOH) chains onto N-phthaloylchitosan(PHCS) backbone.~1H NMR and FTIR results confirmed the molecular structure of the copolymers. The morphology of the supramicelles assembled by PHCS-g-PNVCL was revealed by means of TEM and polarized light microscope. In solution, the supramicelles were very stable as monitored by DLS and zeta potential measurements. Temperature and p H presented significant influences on the size and size distribution of the supramicelles. These supramicelles with multicompartment hydrophobic cores should be ideal biomimetic systems with promising applications in drug delivery.

Continuous microflow visible-light photocatalytic N-formylation of piperidine and its kinetic study

N-formylation of amines,a class of synthetically important reactions,is typically conducted using metal catalysts that are relatively expensive or not readily available and usually needs harsh conditions to increase the reaction efficiency.Here,an efficient continuous microflow strategy was developed for the gas-liquid visible-light photocatalytic N-formylation of piperidine,which achieved a reaction yield of 82.97%and a selectivity of>99%at 12 min using cheap organic dye photocatalyst under mild reaction conditions.The influence of essential parameters,including light intensity,temperature and equivalents of the gas,additive and photocatalyst,on the reaction yield was systematically studied.Furthermore,kinetic investigations were conducted,exhibiting the dependence of reaction rate and equilibrium yield of N-formylpiperidine on light intensity,temperature and photocatalyst equivalent.The microflow photocatalytic approach established in this work,which realized a markedly higher space-time yield than the conventional batch method(37.9 vs.0.212 mmol h-1 L-1),paves the way for the continuous,green and efficient synthesis of N-formamides.

Heat preservation,antifouling,hemostatic and antibacterial aerogel wound dressings for emergency treatment

Hemostatic dressings with multiple functions are superior to current hemostatic dressings for use in the complex situation of emergency accidents.In particular,the existing dressings lack consideration for the prevention of hypothermic shock after massive hemorrhage.In this study,gelatin(GN)and oxidized pectin(OP)were used for Schiff base cross-linking,and then polyvinyl alcohol(PVA)solution mixed with hemostatic caffeic acid(CA)was introduced to obtain aerogel substrate material(CB)after lyophilization.Polydimethylsiloxane(PDMS)and silver nanowires(Ag NWs)were used to construct a hydrophobic layer,an antibacterial layer and an infrared reflective layer on both sides of CB to prepare a multifunctional aerogel wound dressing with heat preservation,antifouling,hemostasis and antibacterial properties(PDMS-Ag NW-CB).The results showed that the infrared transmittance of PDMS-Ag NW-CB is almost 0,so that thermal energy loss from the body is minimized.The contact angles with water and blood are 129°and 120°,respectively,which have the effect of antifouling.This dressing can absorb blood quickly within 10 min,adhere to and gather platelets,and achieve hemostasis.It has good antibacterial and biocompatibility.Therefore,PDMS-Ag NW-CB has great potential in application to emergency treatment.

Facile preparation of low swelling,high strength,self-healing and pH-responsive hydrogels based on the triple-network structure

A polyacrylic acid(PAA)/gelatin(Gela)/polyvinyl alcohol(PVA)hydrogel was prepared by copolymerization,cooling,and freezing/thawing methods.This triplenetwork(TN)structure hydrogel displayed superior mechanical properties,low swelling ratio and self-healing properties,The superior mechanical properties are attributed to the triple helix association of Gela and PVA crystallites by reversible hydrogen bonding.The characterization results indicated that the fracture stress and the strain were 808 kPa and 370% respectively,while the compression strength could reach 4443 kPa and the compressive modulus was up to 39 MPa under the deformation of 90%.The hydrogen bonding in PVA contributed to maintain and improve the self-healing ability of hydrogels.Every type of hydrogels exhibited a higher swelling ratio under alkaline conditions,and the swelling ratios of PAA,PAA/PVA and PAA/Gela hydrogels were 27.71,12.30 and 9.09,respectively.The PAA/Gela/PVA TN hydrogel showed the lowest swelling ratio(6.57)among these hydrogels.These results indicate that the novel TN hydrogels possess good environmental adaptability and have potential applications in the biomedical engineering and sensor field.

Environmentally benign chitosan as reductant and supporter for synthesis of Ag/AgCI/chitosan composites by one-step and their photocatalytic degradation performance under visible-light irradiation

A novel Ag/AgCl/chitosan composite photocatalyst was successfully prepared by a simple one-step method. During this progress, environmentally benign chitosan not only served as reductant to reduce Ag＋ to Ag0 species, but also acted as supporter for Ag/AgCI nanoparticles. XRD, SEM, EDX, UV-vis DRS and XPS were employed to characterize the as-prepared simples. SEM images of Ag/AgCI/chitosan composites revealed that Ag/AgCI nanoparticles were successfully loaded onto chitosan without obvious aggregation. All Ag/AgCI/chitosan composites exhibited efficient photocatalytic activity for the degradation of rhodamine B （RhB） under visible-light irradiation. The result of photocatalytic degradation experiment indicated that 20% of the mass ratio of AgCI to chitosan was the optimum, and after 40 min photocatalytic reaction, the degradation rate reached about 96%.

Novel robust cellulose-based foam with pH and light dual-response for oil recovery

We fabricated pH and light dual-responsive adsorption materials which could induce the transition of surface wettability between hydrophobicity and hydrophilicity by using ATRPo The structure and morphology of adsorption materials were confirmed by ATR-FTIR, XPS, TGA and SEM. It showed that the modified cellulose （CE）- based foam was hydrophobic, which can adsorb a range of oils and organic solvents in water under pH = 7.0 or visible light irradiation （λ〉500 nm）. Meanwhile, the wettability of robust CE-based foam can convert hydrophobicity into hydrophilicity and underwater oleophobicity under pH = 3.0 or UV irradiation （λ = 365 nm）, giving rise to release oils and organic solvents. Most important of all, the adsorption and desorption processes of the modified CE-based foam could be switched by external stimuli. Furthermore, the modified CE-based foam was not damaged and still retained original performance after reversible cycle repeated for many times with variation of surface wettability. In short, it indicates that CE-based foam materials with switchable surface wettability are new responsive absorbent materials and have owned potential application in the treatment of oil recovery.

Sprayable and rapidly bondable phenolic-metal coating for versatile oil/water separation

Phenolic-metal complexation coatings have been discovered to be a universal route for the deposition of multifunctional coatings. However, most complexation coatings have been prepared by the immersion method, which limits their practical large-scale application. Herein, we describe a facile and green engineering strategy that involves spraying phenolic compound and metal ions on substrate to form in-situ complexation coating with different coordination states. The coating is formed within minutes and it can be achieved in large scale by the spray method. The pyrogallol-Fem complexation coating is prepared at pH 7.5, which consists predominantly of biscoordination complexation with a small amount of tris-coordination complexation. It displays that the water contact angle is near zero due to the generation of rough hierarchical structures and massive hydroxyl groups. The superhydrophilic cotton resulting from the deposition of the pyrogallol-Fe^Ⅲ complexation can separate oil/water mixtures and surfactant-stabilized oil-in-water emulsions with high separation efficiency. The formation of the phenolic-metal complexation coating by using spray technique constitutes a cost-effective and environmentally friendly, strategy with potential to be applied for large-scale surface engineering processes and green oil/water separation.

Folate-conjugated pH-responsive nanocarrier designed for active tumor targeting and controlled release of doxorubicin

A novel type of amphiphilic pH-responsive folate-poly（ε-caprolactone）- block-poly（ 2-hydroxyethylmethacrylate ）-co-poly（ 2-（ dimethylamino ）-ethylmethacrylate ） （FA-PCL-b-P（HEMA-co-DMAEMA）） （MFP） block copolymers were designed and synthe- sized via atom transfer radical polymerization （ATRP） and ring opening polymerization （ROP） techniques. The molecular structures of the copolymers were confirmed with IH NMR, FTIR and GPC measurements. The critical micelle concentration （CMC） of MFP in aqueous solution was extremely low （about 6.54 mglL）. The in vitro release behavior of DOX-Ioaded micelles was significantly accelerated when the pH value of solution decreased from 7.4 to 5.0. In vitro antitumor efficiency was evaluated by incubating DOX- loaded micelles with Hela cells. The results demonstrated that this copolymer possessed excellent biocompatibility, and FA-decorated micelles MFP showed higher cellular uptake than those micelles without the FA moiety, indicating their unique targetability. These folate-conjugated biodegradable micelles are highly promising for targeted cancer chemothe-rapy.

One-step synthesis and self-assembly behavior of thermo-responsive star-shaped β-cyclodextrin-（P（M EO2MA-co-PEGMA））21 copolymers

A novel β-cyclodextrin-poly（2-（2-methoxyethoxy）ethyl methacrylate）-co- poly（ethylene glycol） methacrylate （abbreviated as： β-CD-（P（MEO2MA-co-PEGMA））21） was prepared by using the one-step strategy, and then the star-shaped copolymers were used in the atom transfer radical polymerization （ATRP）. The structure of star-shaped β- CD-（P（MEO2MA-co-PEGMA））21 copolymers were studied by FTIR, 1H NMR and gel permeation chromatography （GPC）. The star-shaped copolymers could self-assembled into micelles in aqueous solution owing to the outer amphiphilic β-CD as a core and the hydrophilic P（MEO2MA-co-PEGMA） segments as a shell. These thermo-responsive starshaped copolymers micelles exhibited lower critical solution temperature （LCST） in water, which could be finely tuned by changing the feed ratio of MEO2MA to PEGMA. The LCST of star-shaped β-CD-（P（MEO2MA-co-PEGMA））21 copolymer micelles were increased from 35℃ to 58℃ with the increasing content of PEGMA. The results were investigated by DLS and TEM. When the temperature was higher than corresponding LCSTs, the micelles started to associate and form spherical nanoparticles. Therefore, β- CD-（P（MEO2MA-co-PEGMA））21 star-shaped copolymer micelles could be potentially applied in nano-carrier, nano-reactor, smart materials and biomedical fields.

A novel black TiO2/ZnO nanocone arrays heterojunction on carbon cloth for highly efficient photoelectrochemical performance

ZnO nanocone arrays(NCAs)decorated with black TiO2 nanoparticles(BTiO2 NPs)were uniformly anchored on the surface of carbon cloth(CC)directly by a simply electrochemical deposition method.Thus a novel B-TiO2 NPs/ZnO NCAs-CC hierarchical heterostructure was formed.It displayed superior performance and achieved a higher photocurrent over 0.4 mA·cm^-2 before the onset of the dark current,attributed to the separation of the photogenerated electron-hole pair.Based on the B-TiO2 NPs/ZnO NCAs-CC heterostructure,the catalyst was fabricated for promoting the separation of charge carriers.Moreover,the introduction of Ti^3+ and oxygen vacancies on the surface of TiO2 NPs expanded the absorption band edge and enhanced the electrical conductivity as well as the charge transportation on the catalytic surface.It indicates that the B-TiO2 NPs/ZnO NCAs-CC composite is beneficial to the improvement of the photoelectrochemical(PEC)activity.

Synthesis of poly(maleic acid alkylamide-co-α-olefin-costyrene)and their effect on flow ability of oils

To improve the flow ability of crude oil with high content of aromatic asphaltenes,new comb-type copolymers of poly(maleic anhydride-co-α-olefin-costyrene)(MASCs)with different ratios of maleic anhydride(MA)to styrene were designed and synthesized.1H NMR and FTIR spectra were used to characterize the chemical structure of the copolymers.The effect of copolymers on the flow ability of model waxy oil and crude oil were studied by rheological method and polarizing light microscopy.Upon the addition of MASCs,the yield stresses of oils were decreased by 1 to 3 orders of magnitude,and the morphology of paraffin crystals were reduced and changed from plates to needles.

The formation and catalytic activity of silver nanoparticles in aqueous polyacrylate solutions

Silver nanoparticles （AgNPs） have been synthesized in the presence of polyacrylate through the reduction of silver nitrate by sodium borohydride in aqueous solution. The AgNO3 and polyacrylate carbox- ylate group concentrations were kept constant at 2.0× 10^-4 and 1.0 × 10^-2 mol·L^-1, respectively, while the ratio of [NaBH4]/[AgNO3] was varied from 1 to 100. The ultra- violet-visible plasmon resonance spectra of these solutions were found to vary with time prior to stabilizing after 27 d, consistent with changes of AgNP size and distribution within the polyacrylate ensemble occurring. These obser- vations, together with transmission electron microscopic results, show this rearrangement to be greatest among the samples at the lower ratios of [NaBH4]/[AgNO3] used in the preparation, whereas those at the higher ratios showed a more even distribution of smaller AgNP. All ten of the AgNP samples, upon a one thousand-fold dilution, catalyze the reduction of 4-nitrophenol to 4-aminophenol in the temperature range 283.2-303.2 K with a substantial induction time being observed at the lower temperatures.

Rheological behavior of PMVE-MA aqueous solution with metallic cations

The rheological properties of aqueous solutions of poly(methyl vinyl ether-co-maleic anhydride)(PMVE-MA)upon addition of metallic cations at different pH values were investigated.Sol-gel transition and shearthickening phenomena at moderate shear rate were observed upon increasing the amount of metallic cations,especially for cupric cation.At certain molar ratio(fgel)of added cupric cations to carboxyl groups in PMVE-MA,the system became gel-like,and the storage modulus(G′)and loss modulus(G′′)were parallel and exhibited a power-law dependence on the frequency,which is consistent with Winter’s hypothesis of determining the gel point of a crosslinking system.The shear-thickening behavior depends on fgel,pH,metallic valence,and temperature.

Synthesis of pH-responsive triazine skeleton nano-polymer composite containing AIE group for drug delivery

We exploited a unique porous structure of the nano-covalent triazinepolymer(NCTP)containing aggregation-induced emission(AlE)group to achievecontrolled release and drug tracking in tumor acidic microenvironment.NCTP wassynthesized by the Friedel-Crafts alkylation and the McMurry coupling reaction.It notonly had strong doxorubicin(DOX)-loading capacity due to its high specific surface areaand large pore volume,but also showed the significant cumulative drug release as aresult of the pH response of triazine polymers.NCTP was induced luminescence aftermass accumulation near tumor cells.Besides,it had excellent biocompatibility andobvious antineoplastic toxicity.The results demonstrate that NCTP as a utility-type drugcarrier provides a new route for designing the multi-functional drug delivery platform.

Performance and synergistic effect of phenolic and thio antioxidants in ABS graft copolymers

The synergistic effect of phenolic and thio antioxidants on the stabilization of acrylonitrile-butadienestyrene(ABS)graft copolymers has been studied.Three commercial antioxidants Irganox245,Irganox1076 and dilauryl thiodipropionate(DLTP)were selected.Formulations based on hindered phenols and secondary antioxidant DLTP were prepared.Stabilization was monitored in terms of changes in the functional groups(oxidation products),tensile properties and yellowness index.Differential scanning calorimetry(DSC)and thermogravimetry(TG)were also used to assess the stability.The results indicated that the combination of Irganox245 and DLTP showed much better stabilization effect than the individual components due to the strong synergistic effect.Only weak synergism could be observed in the formulation that contained Irganox1076 and DLTP.Irganox1076 and Irgnox1076/DLTP exhibited similar behaviors between antioxidants with the highest and lowest efficiencies.

Efficient and Generic Preparation of Diverse Polyelectrolyte Nanogels by Electrostatic Assembly Directed Polymerization

Nanogels hold promise as soft and functional carriers and nanoreactors,but whether they will ever reach the stage of large-scale application depends crucially on efficient production methods,and on what interesting properties and functionalities they can have.In particular,nanogels consisting of highly charged polyelectrolyte have not yet been very much explored.Here,the authors present a novel and generic strategy for controlled and efficient synthesis of a large diversity of polyelectrolyte nanogels.The method is based on polymerizing an ionic monomer in the presence of an oppositely charged polyion-neutral diblock copolymer as template,while adding a cross-linker.The growing polymer chains assemble with the template,forming polyion complex micelles,which dissociate upon increasing salt concentration.Subsequent separation yields nanogels with well-controlled size and properties,and free template polymers that can be used again.Our design can be applied generally to a wide range of both cationic and anionic monomers,as well as various cross-linkers.Scaled-up production presents no problems as increasing monomer concentration(hundreds of mM)and reaction volume(up to 1 L)hardly compromise product quality.Moreover,the obtained nanogels with their well-controlled size,morphology,chemistry,and cross-linking degree perform well as soft nanocarriers and catalytic nanoreactors.