Metallosurfactant Ionogels in Imidazolium and Protic Ionic Liquids as Precursors To Synthesize Nanoceria as Catalase Mimetics for the Catalytic Decomposition of H2O2

The gelation behavior of cationic surfactants with different counterions, Br^?, [FeCl₃Br]^?, and [CeCl₃Br]^?, in imidazolium ionic liquids (ILs) and protic ethylammonium nitrate was investigated. Small‐angle X‐ray scattering measurements and freeze‐fracture transmission electron microscopy observations revealed the lamellar phases of metallosurfactant ionogels. The characteristics of imidazolium ILs, including the size and type, have effects on metallosurfactant ionogel properties, such as transformation temperatures, interlayer spacing, and mechanical strength. Cubic fluorite structured cerium oxide nanoparticles (CeO₂ NPs) were produced by using metallosurfactant ionogels as precursors. Cubic fluorite CeO₂ exhibited good catalase mimetic activity toward H₂O₂ to generate O₂, providing more multiple mimetic enzyme activities of CeO₂ NPs for H₂O₂.     

Controllable fabrication of lotus-leaf-like superhydrophobic surface on copper foil by self-assembly

A novel approach was developed to fabricate a lotus-leaf-like superhydrophobic surface on a copper foil by simple self-assembly method with the assistance of the porous PDMS template which was used to adjust the oxidized parts of the copper foil surface before self-assembly. The results showed a series of beautiful flower-like microstructures resulting from the self-assembly of cupric stearate that were distributed at regular intervals on the as-prepared copper foil surface similar to the papillae of lotus leaf surface. The water contact angle of the as-prepared copper surface was up to 161° and its sliding angle was only 3°. Its great superhydrophobicity could be kept unchanged after 6 months in air. The formation mechanism of the lotus-leaf-like structure was discussed. This simple and low-cost method is expected to be applied to design and prepare complicated superhydrophobic surfaces with beautiful regular microstructures on different substrates such as stainless steel, zinc, and so on.     

EB-radiolysis of carbamazepine: in pure-water with different ions and in surface water

A method for the rapid and simultaneous monitoring of particulate and dissolved ¹³⁷Cs concentration in water was developed. This method uses pleated polypropylene nonwoven fabric filter to collect particulate radiocesium, and nonwoven fabric impregnated with Prussian blue (PB) to absorb dissolved radiocesium. The fabric was placed into cylindrical plastic cartridges (SS-cartridge and PB-cartridge). Traditional monitoring methods, such as evaporative concentration, often require time for pre-processing. However, this method described requires much less pre-processing time before the detection. Experiments conducted with simulated river water demonstrated that almost all of the suspended solids weight was collected in the SS-cartridge, and that more than 92 % of dissolved ¹³⁷Cs was absorbed onto the two PB-cartridges by 2.5 L/min flow rate when the range of the pH was 6–8. This device was applied to monitor Abukuma River water at two locations and the results were compared with those obtained using the filtrating and evaporative concentration method. The suspended solids concentration in river water, calculated by weight gain of the SS-cartridge and by sediment weight after filtration with a 0.45-μm membrane filter, agreed well. The radioactivity of the particulate and dissolved ¹³⁷Cs also agreed well in one of the two replications of this method. In addition, the required time for pre-processing was reduced by 60 times that by filtrating and evaporative concentration method. This method can separately collect and concentrate particulate and dissolved radiocesium rapidly and simultaneously in the field.     

Interaction between zero-charged catanionic vesicles and PEO–PPO–PEO triblock copolymers

We investigate the interaction between zero-charged catanionic vesicles and PEO–PPO–PEO (poly(ethylene oxide–poly(propylene oxide)–poly(ethylene oxide)) triblock copolymers. The 25-mg mL^?1 aqueous solution of tetradecyltrimethylammonium laurate (TTAL) contains closely packed uni- and multi-lamellar vesicles and shows viscoelastic properties with a dominant elastic modulus (G′) over a viscous modulus (G″). When a small amount of F127 ((EO)₉₇(PO)₆₉(EO)₉₇) or F68 ((EO)₇₆(PO)₂₉(EO)₇₆) was added, an improvement of the viscoelasticity was observed at suitable polymer concentrations. Freeze–fracture transmission electron microscopy (FF-TEM) observations on an F68-containing system revealed interesting aggregate transition from vesicles to flexible tubules and back to vesicles. The improvement of the viscoelasticity of the vesicular solution containing F68 or F127 can be explained by the formation of tubule and polymer–vesicle associates, while no such phenomenon was noticed for P123 ((EO)₁₉(PO)₆₉(EO)₁₉) which has the highest propylene oxide (PO) content and the strongest ability to self-associate in aqueous solution. In all the cases, vesicles will be destroyed and phase separation can be observed at high polymer contents (>5-mg mL^?1).     

Metal-ligand-coordinated vesicles and vesicle-assisted preparation of calcium oxalate

A Ca(2+) -ligand-coordinated vesicle phase was prepared from a mixture of tetradecyldimethylamine oxide (C14DMAO) and calcium tetradecylamidomethyl sulfate [(CH3(CH2)13NHCOCH2OSO3)2Ca] in aqueous solution. At the appropriate mixing ratios, Ca(2+) -ligand coordination results in the formation of molecular bilayers because Ca(2+) can firmly bind to the head groups of C14DMAO and (CH3(CH2)13NHCOCH2OSO3)2Ca by complexation which reduces the area of head group. In this system, no counterions in aqueous solution exist because of the Ca(2+) -ligand coordination, and the bilayer membranes are not shielded by salts, i.e., a salt-free but charged molecular bilayer. The structures of the birefringent solutions of (CH3(CH2)13NHCOCH2OSO3)2Ca and C14DMAO mixtures were determined by transmission electron microscopy (TEM) images and rheological measurements, demonstrating that the birefringent sample solutions consist of vesicles. The Ca(2+) -ligand complex vesicle phase was used as a microreactor to prepare calcium oxalate (CaC2O4) crystals. Dimethyl oxalate, as a precursor, can hydrolyze to oxalic acid and methanol. Oxalic acid should precipitate Ca(2+) ions binding to the head groups of C14DMAO and (CH3(CH2)13NHCOCH2OSO3)2Ca to produce CaC2O4 crystals (Ca(2+) + H2C2O4 --> CaC2O4 (downward arrow) + 2H+). The obtained particles were CaC2O4 monohydrate, which were dominated by (020) faces. CaC2O4 precipitates were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) analysis. After removal of CaC2O4 precipitates, a new cationic and anionic (catanionic) vesicle phase was constructed through electrostatic interaction between cationic C14DMAOH+ (C14DMAO + H+ --> C14DMAOH+) and anionic CH3(CH12)13 NHCOCH2OSO3-.     

In situ hydrothermal synthesis of nanolamellate CaTiO3 with controllable structures and wettability

Nanolamellate structures of CaTiO3 were fabricated by using an in situ hydrothermal synthesis method on titanium for the first time. The number of nanolamellas and the morphology completely or mainly depend on the reaction time and NaOH concentrations, and the wettability of the resulting CaTiO3 surfaces can be successively turned from superhydrophilic to superhydrophobic after modification with a thin layer of hydrophobic silicone, mainly depending on the surface morphology. The proposed formation mechanism of the nanolamellate CaTiO3 structures has also been discussed.     

Alkali-metal hexamethyldisilazide initiated polymerization on alpha-amino acid N-substituted N-carboxyanhydrides for facile polypeptoid synthesis

Polypeptoids have been explored as mimics of polypeptides,owing to polypeptoids' superior stability upon proteolysis.Polypeptoids can be synthesized from one-pot ring-opening polymerization of amino acid N-substituted N-carboxyanhydrides(NNCAs).However,the speed of polymerization of NNCAs can be ve ry slow,especially for NNCAs bearing a bulky N-substitution group.This hindered the explo ration on polypeptoids with more diverse structures and functions.Therefore,it is in great need to develop advanced strategies that can accelerate the polymerization on inactive NNCAs.Hereby,we report that lithium/sodium/potassium hexamethyldisilazide(Li/Na/KHMDS) initiates a substantially faster polymerization on NNCAs than do commonly used amine initiators,especially for NNCAs with bulky Nsubstitution group.This fast NNCA polymerization will increase the structure diversity and application of polypeptoids as synthetic mimics of polypeptides.     

A nanocomposite consisting of carbon nanotubes and gold nanoparticles in an amphiphilic copolymer for voltammetric determination of dopamine,paracetamol and uric acid

The amphiphilic copolymer poly(vinylbenzyl thymine-co-styrene-co-maleic anhydride) (PSVM) was synthesized by radical copolymerization of styrene, vinylbenzyl thymine, and maleic anhydride. Its chemical structure was proven by using ¹H nuclear magnetic resonance spectroscopy. PSVM was used as a host to prepare a composite consisting of carbon nanotubes and gold nanoparticles by in-situ reduction. The morphology of the nanocomposites was studied by transmission electron microscopy. A glassy carbon electrode coated with this composite is shown to be a viable sensor for the determination of dopamine (DA), paracetamol (PAT) (both at a pH value of 7), and uric acid (UA) (at pH 6). Two linear relationships exists between amperometric current and analyte concentrations. For DA, the linear analytical ranges are from 0.1 to 200 μM and from 200 to 1000 μM. For PAT, the ranges are from 0.1 to 200 μM and from 200 to 1000 μM. For UA, the ranges are from 0.05 to 1000 μM. The respective limits of detection (for S/N = 3) are 56, 27 and 50 nM. The sensor is highly sensitive, stable, reproducible, and selective.

Open image in new window

Graphical abstract A hybrid nanocomposite (CNT/PSVM/Au) of carbon nanotube (CNT) – Au nanoparticle composite based on the amphiphilic copolymer poly(vinylbenzyl thymine/styrene-co-maleic anhydride) (PSVM) was prepared through in situ reduction. This nanocomposite was immobilized on a glassy carbon electrode (GCE) to fabricate an electrochemical sensor to determine dopamine (DA), paracetamol (PAT) and uric acid (UA).