Xiaobin Huang

Fluorescent organic–inorganic hybrid polyphosphazene microspheres for the trace detection of nitroaromatic explosives

Highly cross-linked, intrinsically fluorescent organic–inorganic hybrid polymer microspheres bearing primary amine groups on the surface have been successfully prepared through a one-pot polycondensation of hexachlorocyclotriphosphazene with benzidine. Just by the single-step introduction of plentiful π-conjugated benzidine units in the structure, the resulting microspheres easily obtain both the luminescence and abundant active amino groups, with no need for more modification. Thus further using the microspheres as fluorescence-based nitroaromatic sensor, 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and picric acid can be effectively and sensitively detected. Because the nitroaromatic analytes can be effectively enriched on the surface of the microspheres by the charge-transfer complexing interaction between electron-deficient aromatic rings and electron-rich amino groups, which facilitates the electron transfer and energy transfer from microspheres to nitroaromatics, and finally leads to a significant and sensitive fluorescence quenching response. Moreover, the microspheres also exhibit remarkable thermal stability, photobleaching stability, and solvent resistance and dispersion ability in various solvents including both aqueous and organic media, owing to the highly cross-linked and organic–inorganic hybrid structure.

Novel preparation of polyphosphazene-coated carbon nanotubes as a Pt catalyst support

This study reports a noncovalent functionalization of MWCNTs with a fluorinated cross-linked polymer coating of poly[cyclotriphosphazene-co-(4,4-(hexafluoroisopropylidene)diphenol)] and their application as the support of Pt for electrocatalytic oxidation of methanol.

Enhancement of the electrocapacitive performance of manganese dioxide by introducing a microporous carbon spheres network

An amorphous MnO(2)·nH(2)O/microporous carbon spheres (α-MnO(2)·nH(2)O/MCS) composite electrode material is prepared by a chemical co-precipitation method. It is observed that the amorphous MnO(2) particles are deposited on the surface of the MCS, which form a network with a uniquely developed three-dimensional open porous system containing macropores, mesopores and micropores. The electrochemical measurements reveal that the composite electrode material presents a much more stable and reversible capacitance behavior compared to the pure α-MnO(2)·nH(2)O in 1 M of Na(2)SO(4) electrolyte. The composite containing 25 wt% MCS exhibits optimal specific capacitance of 218.2 F g(-1) at 2 mV s(-1), and is still as high as 112.4 F g(-1) at 100 mV s(-1), while a drastic reduction from 197.0 F g(-1) at 2 mV s(-1) to only 40.7 F g(-1) at 100 mV s(-1) occurs for the pure α-MnO(2)·nH(2)O. The composite also shows a rather high electrode-specific capacitance of 3.13 F cm(-2) and a long cycle life. The remarkable enhancement in the electrochemical performance is mainly attributed to the microporous structure of the MCS contributing to the deposition of MnO(2) particles on the surface of the MCS, and the uniquely developed porous network of the composite facilitating the rapid transport of the electrolyte. These factors result in the high electrochemical utilization of MnO(2), a great reduction of the equivalent series resistance, and hence the relatively high and stable electrochemical behavior.

Controlled fabrication of noble metal nanoparticles loaded on the surfaces of cyclotriphosphazene-containing polymer nanotubes

We report on the fabrication of noble metal nanoparticles loaded on the surfaces of cross-linked poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanotubes of high stability. PZS nanotubes were first synthesized by precipitation polymerization between hexachlorocyclotriphosphazene and 4,4′-sulfonyldiphenol based on in situ template mechanism. Then the PZS nanotubes were directly used as scafford to load metal Au, Ag, and Pd nanoparticles, respectively, through cation complexation followed by gentle reduction. The structure and morphology of the metal/PZS nanocomposites were determined by means of Fourier transform infrared spectra, energy dispersive X-ray spectroscopy, elemental analysis, X-ray diffraction, scanning electron microscope, transmission electron microscope, and thermogravimetric analysis (TGA). Results showed that the metal/PZS nanocomposites possessed 460xa0°C of initial thermal decomposition temperature under air atmosphere and the loading amount of metal nanoparticles on the PZS nanotube surfaces could be controlled easily. As-fabricated metal/PZS nanocomposites are expected to have potential applications in catalysis.

Preparation and electrochemical behaviors of composite solid polymer electrolytes based on polyethylene oxide with active inorganic–organic hybrid polyphosphazene nanotubes as fillers

Inorganic–organic hybrid porous poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanotubes with active hydroxyl groups are incorporated in polyethylene oxide (PEO), using LiClO4 as doping salts, to form a novel composite polymer electrolyte (CPE). The composite solid polymer electrolytes are characterized using differential scanning calorimetry (DSC), atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrical impedance spectroscopy. The SEM photographs indicate that the electrolytes are miscible and homogeneous. Incorporation of active PZS nanotubes in PEO–LiClO4 polymer electrolytes facilitates salt dissociation and enhances ionic conductivity. Maximum ionic conductivity values of 4.5 × 10−5 S cm−1 at ambient temperature and 1.56 × 10−3 S cm−1 at 80 °C are obtained when the content of active PZS nanotubes is 10 wt% and the lithium ion transference number is 0.39. The experiment results show that the inorganic–organic hybrid polyphosphazene nanotubes with active hydroxyl groups can enhance the ionic conductivity and increase the lithium ion transference number of PEO-based electrolytes more effectively comparing with traditional ceramic fillers such as SiO2.

Synthesis and Characterization of a Novel Curing Agent for Epoxy Resin Based on Phosphazene Derivatives

In this work, a novel amine-terminated curing agent for epoxy resin based on hexachlorocyclotriphosphazene (HCCP) was synthesized through two steps of nucleophilic substitution reactions by phenol and 4-aminophenol. Its chemical structure was characterized by 1H-NMR, Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). This curing agent was liquid at room temperature which made it easy to disperse in the epoxy resin. The rheological test showed the viscosity of the pre-polymer fluid decreased as the proportion of the curing agent increased so it improved the process performance. The curing reaction was studied by differential scanning calorimeter (DSC). The novel curing agent had a wider range of curing temperature and relatively lower curing temperature in comparison with the widely-using curing agent 4,4′-Diaminodiphenylmethane (DDM). The wider range of curing temperature helped lower the heat accumulation which was an important factor in curing process.

Hybrids based on transition metal phosphide (Mn2P, Co2P, Ni2P) nanoparticles and heteroatom-doped carbon nanotubes for efficient oxygen reduction reaction

Hybrids based on transition metal phosphide (Mn2P, Co2P, Ni2P) nanoparticles and heteroatom-doped carbon nanotubes were facilely synthesized, and used as efficient oxygen reduction reaction (ORR) catalysts in alkaline solution. Transition metal phosphide nanoparticles formed core/shell structures with graphitic carbon, and the nanoparticles (core) can significantly influence the ORR catalytic activity of the carbon shell. Hybrids based on Co2P and Mn2P decorated heteroatom-doped carbon exhibit excellent ORR catalytic activity with regards to dominant 4e− process, low over potential, excellent methanol tolerance and durability. In contrast, Ni2P decorated heteroatom-doped carbon shows inferior ORR catalytic activity. The variation of ORR performance mainly derives from the collective effect of the electronegativity and binding energy shift of the transition metals, which would result in a different surface electronic structure of the heteroatom-doped carbon. Low electronegativity and low binding energy shift of the transition metals would lead to strong electron-donating ability of the transition metal phosphide nanoparticles, resulting in the enhanced ORR catalytic activity of the hybrid materials. This work is significant for development of advanced ORR catalysts based on heteroatom-doped carbon via rational design of the structure of hybrid materials.

Facile preparation of hollow crosslinked polyphosphazene submicrospheres with mesoporous shells

A facile strategy has been successfully developed to fabricate hollow crosslinked polyphosphazene submicrospheres. The mean diameter of interior cavities can be well adjusted (typically in a range from 100 to 300 nm). Interestingly, there are plenty of uniform mesopores distributing in the organic-inorganic hybrid shells. The main pore size of the mesopores is about 2–4 nm. Such hollow mesoporous submicrospheres (HMSs) possess outstanding biocompatibility and disperse ability in both aqueous and organic media. Moreover, these crosslinked polyphosphazene HMSs manifest high drug storage capacity (380 mg doxorubicin hydrochloride per gram) and excellent sustained release property (up to 15 days), hence justifying their promising applications in drug delivery.

Intrinsically fluorescent nanoparticles with excellent stability based on a highly crosslinked organic–inorganic hybrid polyphosphazene material

A series of intrinsically fluorescent particles were synthesized, including nanoparticles with independently tunable diameters, nanotubes and microspheres, based on a highly crosslinked organic-inorganic hybrid polyphosphazene material. The nanoparticles exhibit high fluorescent intensity and excellent thermal and photobleaching stability, and can be well dispersed in both aqueous and organic media.

Enhanced electrochemical properties of polyethylene oxide-based composite solid polymer electrolytes with porous inorganic–organic hybrid polyphosphazene nanotubes as fillers

Solid composite polymer electrolytes consisting of polyethylene oxide (PEO), LiClO4, and porous inorganic–organic hybrid poly (cyclotriphosphazene-co-4, 4′-sulfonyldiphenol) (PZS) nanotubes were prepared using the solvent casting method. Differential scanning calorimetry and scanning electron microscopy were used to determine the characteristics of the composite polymer electrolytes. The ionic conductivity, lithium ion transference number, and electrochemical stability window can be enhanced after the addition of PZS nanotubes. The electrochemical impedance showed that the conductivity was improved significantly. Maximum ionic conductivity values of 1.5u2009×u200910−5xa0Sxa0cm−1 at ambient temperature and 7.8u2009×u200910−4xa0Sxa0cm−1 at 80xa0°C were obtained with 10xa0wt.% content of PZS nanotubes, and the lithium ion transference number was 0.35. The good electrochemical properties of the solid-state composite polymer electrolytes suggested that the porous inorganic–organic hybrid polyphosphazene nanotubes had a promising use as fillers in SPEs and the PEO10–LiClO4–PZS nanotube solid composite polymer electrolyte might be used as a candidate material for lithium polymer batteries.