Haojie Yu

Hollow Ferrocenyl Coordination Polymer Microspheres with Micropores in Shells Prepared by Ostwald Ripening

Hollow microspheres with pores in their shells have received much attention owing to their hierarchically porous structures and advanced applications in electrochemical capacitive energy storage, hydrogen storage, drug delivery, sensing, and catalysis. For example, Lou et al. reported that hollow SnO2 nanospheres with nanoporous shells showed high reversible charge capacity and good cycling performance. Zhu et al. investigated the drug-delivery properties of hollow silica spheres with mesoporous shells and found that the hollow microspheres were able to store significantly more molecules with higher release rates than conventional mesoporous silica. Template synthesis is one of the most-used strategies to prepare hierarchically hollow microspheres, especially for pores inside the shells. Braun and co-workers have prepared hollow ZnS microspheres with mesoporous shells using dual templates assembled by lyotropic liquid crystals on the surfaces of silica or polystyrene colloidal templates. Liu et al. have produced organic–inorganic hybrid hollow nanospheres with microwindows on the shells templated by tricopolymer aggregates. The template method is general to prepare hollow microspheres with pores in the shells, but expensive and tedious post-treatment processes, such as solvent extraction, thermal pyrolysis, or chemical etching, and resultant fragile frameworks, limit or even impair its applicability. 3, 4] As a result, it remains an important challenge to develop a convenient and template-free method to prepare hollow microspheres with porous shells. Porous coordination polymers are highly ordered porous multifunctional materials prepared by linking metal ions or metal oxide clusters with multidentate organic ligands without any additional template. Construction of shells of hollow materials with porous coordination polymers is an especially promising approach to design hollow microspheres with porous shells through a template-free method and to endow materials with multifunctionality, such as electric, magnetic, and optical properties. Herein, we report the formation of hollow coordination polymer microspheres with microporous shells by a one-pot solvothermal reaction without any additional template; the shells are constructed of iron-based ferrocenyl coordination polymers. We confirm that the Ostwald ripening mechanism is responsible for the formation of hollow cavities with controllable size. Hollow iron-based ferrocenyl coordination polymer microspheres (Fe-Fc-HCPS) were synthesized by a solvothermal reaction of FeCl3·6H2O with 1,1’-ferrocenedicarboxylic acid (H2FcDC) in N,N-dimethyl formamide (DMF; Figure 1a). The precipitate was collected by centrifugation and washed several times with DMF and CHCl3. The reaction temperature, reaction time, and molar ratio of reactants play important roles in the formation of hollow spherical particles. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and optical microscopy (OPM) were

The influence of seeding conditions and shielding gas atmosphere on the synthesis of silver nanowires through the polyol process

The polyol process including the introduction of preformed seeds and the inducement of poly(vinyl pyrrolidone) (PVP) has been developed as a powerful approach for synthesizing silver nanowires. Here, silver nanowires without other metal elements as impurities were synthesized through a silver seeding polyol process in a shielding gas atmosphere. It is demonstrated that the first seeding step is critical in obtaining silver nanowires as the principal product, and we also observe that the shielding gas atmosphere not only improves the repeatability of experiments but also affects the morphology of the final product. We obtained nanocubes with hydrogen gas shielding in a short reaction time; these would scarcely appear with argon or air shielding. Our work supplies new evidence to explain the actual growth mechanism of silver nanowires.

Current progress on the modification of carbon nanotubes and their application in electromagnetic wave absorption

In modern times, with the rapid development of technology, science and economy, applications of electromagnetic (EM) wave absorption in both commercial and military fields have increased. Meanwhile, the problems brought by EM wave absorption have gradually become obvious, such as signal interference, back-radiation of microstrip radiators and so on. Furthermore, the impact of EM wave radiation on human health has also attracted much public attention. In this regard, the application of EM wave absorbing materials has become a focus of current research. Due to their unique chemical, physical, and mechanical properties, carbon nanotubes (CNTs), through certain modifications for light mass, wide range and strong absorption, have great potential to be used as excellent EM wave absorbents. This review highlights recent research into the modification of CNTs, with special emphasis on their EM wave absorbing ability.

Review on synthesis of ferrocene-based redox polymers and derivatives and their application in glucose sensing

The interest in glucose biosensors persisted over many years and persistent efforts have been made to develop long term stable glucose biosensors with precision, smart analytical performance, good linearity and resistance to communal interferences. In this regard, ferrocene-based polymers and derivatives (FBPDs) for the development of glucose biosensor (GBs) as redox mediators have acquired utmost attention of the scientists, especially in the second generation biosensors, as a large number of innovative molecules have been synthesized. Most of the FBPDs are considered as active components in the development of GBs, due to their ease of modification, biocompatibility, stability, large surface area, good electrical conductivity and especially excellent redox properties. This review provides a brief description of synthesis, analytical performance and glucose sensing application of ferrocene-based dendrimers, polythiophenes, polypyrroles, polyethylenimine, chitosan and carbon nano tubes (CNTs). Moreover, the analytical performance of ferrocene-based glucose biosensors (FBGBs) is summarized and the problems associated with the construction of GBs and the future trends are discussed.

Templated preparation of porous magnetic microspheres and their application in removal of cationic dyes from wastewater.

Porous magnetic microspheres with large particle size (350-450 microm) were prepared with sulfonated macroporous polydivinylbenzene as a template. The preparation process included ferrous ion exchange and following oxidation by hydrogen peroxide. The results showed that the weight fraction of magnetic nanoparticles exceeded 20 wt% in microspheres after the preparation process was repeated three times. X-ray diffraction profiles indicated that the crystalline phase of as-formed magnetic nanoparticles was magnetite (Fe(3)O(4)). TEM images revealed rod-like magnetite crystal after the first oxidation cycle, however, the crystal morphologies were transferred into random shape after more oxidation cycles. The applicability of porous magnetic microspheres for removal of cationic dyes from water was also explored. The results exhibited that basic fuchsin and methyl violet could be quickly removed from water with high efficiency. More importantly, the magnetic microspheres could be easily regenerated and repeatedly employed for wastewater treatment. Therefore, a novel methodology was provided for fast removal cationic dyes from wastewater.

Recent progress in the preparation of polyaniline nanostructures and their applications in anticorrosive coatings

Research on composites/blends containing polyaniline (PANI) has attracted numerous scientists and engineers due to their excellent adhesion and anticorrosive properties. Nano-structured PANI composites and matrix resins play a key role in physical and anticorrosive performance. This paper reviews the synthesis, growth mechanisms and corrosion application with different resin coatings of PANI-based nano-composites. It also highlights the failures of corrosion protection and methods and suggestions to improve it.

Synthesis of Fe3O4@poly(methylmethacrylate-co-divinylbenzene) magnetic porous microspheres and their application in the separation of phenol from aqueous solutions

A simple strategy to fabricate magnetic porous microspheres of Fe(3)O(4)@poly(methylmethacrylate-co-divinylbenzene) was demonstrated. The magnetic microspheres, consisting of polymer-coated iron oxide nanoparticles, were synthesized by the modified suspension polymerization of methacrylate and divinylbenzene in the presence of a magnetic fluid. The morphology and the properties of the magnetic porous microspheres were examined by scanning electron microscopy, transmission electron microscopy, superconducting quantum interference device, Fourier transform infrared spectroscopy, thermogravimetry, and X-ray powder diffraction. The pore size distribution and the specific surface area of the microspheres were measured by nitrogen sorption and mercury porosimetry technique. As predicted from the previous knowledge, the magnetic porous microspheres possessed a high specific surface area using n-hexane as a porogen. It was further found that the amounts of divinylbenzene and methacrylate, the ratio of porogens, and the dosage of ferrofluids affect the specific surface area of the microspheres. Furthermore, the microspheres were applied to remove phenol from aqueous solutions. The results showed that the microspheres had a high adsorption capacity for phenol and a high separation efficiency due to their porous structure, polar groups, and superparamagnetic characteristic.

Recent progress on synthesis, property and application of modified chitosan: An overview

Because of the unique chemical structure, chitosan and its derivatives have been paid close extensive attention as the potential bio-functional material. This review presents recent synthesis of modified chitosan via N-substitution, O-substitution, free radical graft copolymerization and other modification methods and properties of the modified chitosan. The applications of the modified chitosan in metal ions adsorption, dye removal and pharmaceutical fields are illustrated as well. The rapid development in the modification of chitosan describes broad perspectives of the modified chitosan.

Recent progress in chemical modification of starch and its applications

Starch has received much attention as a promising natural material both in biomedical fields and waste water treatment due to its unique biological and adsorptive properties. Recently, the modification of starch is rapidly developed along with its growing applications. This review focuses on the ways of chemical modification of starch including cross-linking, grafting, esterification, etherification, dual modification and so on, and presents the applications of the modified starch in fields like drug delivery, tissue engineering and heavy metal and dye removal.

Electrochemical assessment of the interaction of dihydrogen phosphate with a novel ferrocenyl receptor.

A novel ferrocene-based amide has been synthesized by condensation reaction and characterized by (1)H NMR and UV-vis spectroscopies. The electrochemical properties and anion recognition properties of the ferrocene-based amide were investigated by the CV and UV-vis techniques. An interesting phenomenon was revealed by CV: a second oxidative peak, and the first oxidative peak decreased. Therefore, an effective dihydrogen phosphate recognition sensor is expected from this compound in the future.