Huarong Liu

A simple reduction-oxidation route to prepare Co3O4 nanocrystals

Abstract Cobalt oxide (Co3O4) nanoparticles have been successfully prepared via a simple reduction-oxidation route at room temperature and normal pressure, using cobalt chloride as the reactant and sodium acetate as the basic agent. Owing to employing a γ-irradiation technique, no extra reducing reagent was introduced into the system. The experiment contained two steps: first, cobalt (II) ions were reduced to cobalt atoms by γ-irradiation in nitrogen. Then, cobalt atoms were oxidized to cobalt oxide (Co3O4) in air. The TEM images showed that cobalt oxide powders consisted of crystallized spherical particles and amorphous wire-like particles.

Synthesis and characterization of polyacrylonitrile–silver nanocomposites by γ-irradiation

The nanocomposites of stable nanosilver particles embedded in polyacrylonitrile matrix were synthesized by γ-irradiation, in which the monomer acrylonitrile was polymerized and the silver ions were reduced simultaneously by γ-irradiation to form composites in situ. The strong interactions between silver ions with –CN groups of polyacrylonitrile are found, which were confirmed by X-ray powder diffraction, IR spectrum and absorption spectra.

Fabrication of novel multihollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via water-in-oil-in-water double emulsions.

We herein present a novel and simple synthetic strategy for fabricating multihollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via water-in-oil-in-water double emulsions. Amphipathic magnetite nanoparticles surface-modified with oleic acid act as an oil-soluble emulsifier and sodium dodecyl sulfate acts as a water-soluble surfactant in the system. The final products were thoroughly characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy, which showed the formation of multihollow magnetite/polystyrene nanocomposite microspheres. Preliminary results of magnetic properties of multihollow magnetite/polystyrene microspheres were reported. The effect of the content of amphipathic magnetite nanoparticles on the morphology of nanocomposite microspheres was studied. Furthermore, the mechanism of formation of multihollow magnetic nanocomposite microspheres was also discussed.

Design of yolk–shell Fe3O4@PMAA composite microspheres for adsorption of metal ions and pH-controlled drug delivery

Core–shell–shell structured Fe3O4@SiO2@PMMA composite microspheres were synthesized on a large scale by combining sol–gel reaction and seeded emulsion polymerization. The yolk–shell structured Fe3O4@PMAA microspheres with pH-responsive shells were then produced by the hydrolysis reaction of the PMMA shells in NaOH aqueous solution during etching of the silica interlayers. The resulting microspheres, with tunable void space and shell thickness, were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and dynamic laser scattering (DLS). The effect of shell thickness and void space of the yolk–shell Fe3O4@PMAA microspheres on the adsorption of metal ions and drug delivery was investigated. The results demonstrated the excellent adsorption capacity of Cu2+ and Pb2+ and reusability for Cu2+ using the optimum Fe3O4@PMAA microspheres as adsorbents under weakly acidic conditions, as well as the high loading capacity and pH-controlled release ability of yolk–shell Fe3O4@PMAA microspheres by loading ceftriaxone sodium and performing a controlled release study.

Novel Walnut-like Multihollow Polymer Particles: Synthesis and Morphology Control

Novel walnut-like multihollow polymer particles were first prepared by gamma-ray radiation emulsion polymerization using cross-linked and sulfonated polystyrene spheres (CSPs) as the template. The formation process was studied in detail, and the morphology of walnut-like multihollow polystyrene particles could be controlled by the content of cross-linking agent, sulfonation time of CSP particles, and the weight ratio of monomer/CSP. In addition, an application of walnut multihollow polymer particles on bonding Ag nanoparticles onto the surface was achieved, which could be extended to other noble metal nanoparticles and could have a wide range of potential applications, such as catalysts, sensors, solar cells, and photonic crystals.

Preparation and characterization of film-forming raspberry-like polymer/silica nanocomposites via soap-free emulsion polymerization and the sol–gel process

AbstractHerein, we report on the synthesis of film-forming poly(styrene-co-butyl acrylate-co-acrylic acid)/SiO2 [P(St-BA-AA)/SiO2] nanocomposites by in situ formation of SiO2 nanoparticles from TEOS via sol–gel process in the presence of poly(acrylic acid) (PAA)-functionalized poly(styrene-co-butyl acrylate) [P(St-BA)] particles fabricated by soap-free emulsion polymerization. The formed silica particles could be absorbed by polyacrylate chains on the surface of PAA-functionalized P(St-BA) particles; thus, raspberry-like polymer/silica nanocomposites would be obtained. Transmission electron microscopy, Fourier transform infrared spectroscopy, attenuated total reflectance infrared spectrum, ultraviolet–visible transmittance spectra, and thermogravimetric analysis were used to characterize the resulting composites. The results showed that the hybrid polymer/silica had a raspberry-like structure with silica nanoparticles anchored on the surface of polymer microspheres. The thermal, fire retardant, and mechanical properties and water resistance of the film were improved by incorporating silica nanoparticles, while the optical transmittance was seldom affected due to nanosized silica particles uniformly dispersed in the film. FigureFilm-forming polymer/silica nanocomposites with raspberry-like morphology have been successfully prepared via soap-free emulsion polymerization followed by the sol–gel process. The number and the size of SiO2 particles coated on the surface of polymer particles can be adjusted by the amounts of TEOS and ammonia. After the film formation of polymer/silica nanocomposites, silica nanoparticles are homogeneously dispersed within the film without aggregation.

The formation mechanism of Cu–Pd alloys in mixed aqueous solutions by γ-irradiation

Abstract The formation of the dispersed phase was studied by absorption spectroscopy in γ-irradiated mixed aqueous solutions of Cu(II) and Pd(II) in presence of isopropanol. The formation mechanism of bimetallic colloid was discussed through the comparisons with copper and palladium colloids. The crux of the formation of Cu–Pd alloy was investigated through the influences of experimental conditions on the formation of Cu–Pd alloy.

Preparation of High Internal Water-Phase Double Emulsions Stabilized by a Single Anionic Surfactant for Fabricating Interconnecting Porous Polymer Microspheres

Herein we report a one-step method to prepare high internal water-phase double emulsions (W/O/W) via catastrophic phase inversion of water-in-oil high internal phase emulsions (W/O HIPEs) stabilized solely by 12-acryloxy-9-octadecenoic acid (AOA) through increasing the content of water phase. This is the first time for double emulsions to be stabilized solely by a single small molecular surfactant, which are usually costabilized by both hydrophilic and hydrophobic surfactants. After neutralized with ammonia, AOA is confirmed to be capable of stabilizing both W/O emulsions and O/W emulsions, which may account for its unique ability to stabilize double emulsions. The effects of different conditions (including changing the concentrations of AOA and salt (NaCl), pH value, the polarity of oils, the addition interval of water and stirring rate, etc.) on the formation and the stability of double emulsions as well as the inversion point have been investigated by using optical microscopy and conductivity monitoring. Finally, porous polymer microspheres with high interconnection (polyHIPE microspheres) were fabricated by γ-ray initiated polymerization of the as-prepared double emulsions composed of different monomers (styrene, or n-butyl acrylate, or methyl methacrylate), which have been confirmed by scanning electron microscopy. Our method is facile and effective for preparing high interconnecting porous polymer microspheres without tedious post-treatment of the products in common emulsion polymerization due to the use of polymerizable surfactant.

Synthesis and characterization of polyacrylamide–nickel amorphous nanocomposites by γ-irradiation

Abstract Polyacrylamide–nickel amorphous nanocomposites were first synthesized by γ-irradiation and the amorphous nickel nanoparticles of near uniform size were well dispersed in the polymer matrix. The absorption band at 270 nm may be due to nickel clusters of a nonmetallic nature.

Facile fabrication of snowman-like Janus particles with asymmetric fluorescent properties via seeded emulsion polymerization

AbstractThis paper presents a facile method for the preparation of snowman-like Janus particles (SJP) with asymmetric fluorescent property via seeded emulsion polymerization, in which in situ formed raspberry-like cadmium sulfide/poly(styrene–divinylbenzene–acrylic acid) nanocomposite particles (RNP) were used as the seeds. The as-prepared RNP and SJP have been thoroughly characterized by transmission electron microscopy, field-emission scanning electron microscopy, thermogravimetric analysis, X-ray powder diffraction, Fourier transform infrared, ultraviolet visible, and photoluminescent spectrometry. It is found that the size ratio of the polymer bulge/inorganic seed part could be continuously tuned as well as the composition of polymer bulges by changing the composition of monomer mixtures and monomer/seed weight ratio. The obtained Janus particles possess amphiphilic properties which can be further used as solid surfactants to stabilize W/O emulsions and successively to construct hierarchical structured materials. Meanwhile, their asymmetric fluorescent properties may be exploited to detect their assembled situation and orientation at the oil–water interface of emulsions as well as at the surface of hierarchical structured materials. FigureSnowman-like Janus particles with asymmetric fluorescent property are successfully synthesized via seeded emulsion polymerization using in situ formed raspberry-like cadmium sulfide/poly(styrene–divinylbenzene–acrylic acid) nanocomposite particles as the seeds