Dongjian Shi

Chelating template-induced encapsulation of NiO cluster in mesoporous silica via anionic surfactant-templated route.

In this study, we develop a novel one-step method for synthesis of nickel oxide/silicon dioxide (NiO/SiO(2)) mesoporous composites by using N-hexadecyl ethylenediamine triacetate (HED3A) as structure-directing agent. Besides playing a role in directing the mesophase formation, the anionic surfactant also functions as a chelating agent that binds nickel ions. Ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopic analyses were undertaken to determine the chelating ability between HED3A and nickel ions. By adjusting the molar ratio of Ni(2+)/HED3A in the template solution, a series of mesoporous composites with various NiO contents were obtained after calcination. These composites were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and nitrogen adsorption/desorption. The results showed that the generated NiO nanoparticles were aggregated into clusters with the size less than 20 nm, and the composites retained mesoporous characteristics even with high NiO contents. HRTEM images also revealed the migration and aggregation for NiO nanoparticles during the sintering process. Moreover, the energy-dispersive X-ray spectrum (EDX) results showed a close linear relationship between Ni/Si in the composites and Ni(2+)/HED3A in the templates. This chelating surfactant-assistant encapsulation route has the potential to synthesize diversiform metal oxide/silica mesoporous composites with designated compositions.

Co-deposition motif for constructing inverse opal photonic crystals with pH sensing

Polyacrylamide (PAM) hydrogel photonic crystals with an inverse opal structure were elaborated using a modified vertical deposition approach involving a co-deposition motif. Free-standing inverse opal hydrogel (IOH) films of different thicknesses that could be peeled from the support were first fabricated. A three-dimensional ordered structure without over-layers could easily be acquired by the co-deposition approach. Moreover, the bi-continuous structure was not affected by the increase in film thickness. All these IOH films showed a fascinating pH response property after hydrolysis, and the color change corresponding to the shift of the Bragg diffraction peak of the acquired hydrogel photonic crystal films could be easily distinguished by the naked eye. Three types of IOH films with different thicknesses showed similar pH response properties. The co-deposition approach is found to be suitable for the construction of thicker IOH film without over-layers.

Fabrication of Uniform Nanocomposite by “Anchoring” Polyaniline Nanofibers on the Surface of Graphene Oxide for Supercapacitors

In this research, polyaniline/graphene oxide (PANI/GO) nanocomposite was prepared via covalent grafting by anchoring PANI on the surface of GO. Firstly, aniline (ANI) was anchored on the surface of GO by a series of chemistry reactions to obtain ANI modified GO (GO-ANI). The subsequent in situ polymerization of ANI monomer on the surface of GO led to the fabrication of a uniform PANI/GO nanocomposite. The morphology and structure of the products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), ultraviolet-visible spectrophotometer (UV-vis), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed the formation of the uniform PANI/GO nanocomposite with the PANI nanofibers anchoring on the GO surface. Such structure afforded high specific capacitance during the charge-discharge process for supercapacitor electrodes. The specific capacitance of the nanocomposite was 275 F/g, which was higher than that of pure PANI (192 F/g). The nanocomposite exhibits good electrochemical property and is a good candidate for supercapacitor electrodes.

Gold-loaded polymeric micelles with temperature-modulated catalytic activity

Four-armed amphiphilic block copolymers, polystyrene-b-poly(N-isopropylacrylamide) (PS-b-PNIPAM)4, were synthesized by atom transfer radical polymerization (ATRP). (PS-b-PNIPAM)4 self-assembled into micelles with PS block as core and thermoresponsive PNIPAM block as corona. The gold nanoparticles (Au NPs) with average diameter about 5.8 nm were immobilized on the surfaces of the micelles by the reduction of the corresponding ions. The micelle-supported gold nanoparticles (Au-micelles) were applied to catalyze the reduction of p-nitrophenol. Moreover, the activity of the Au-micelle catalyst could be modulated by the temperature and the Au-micelles could be easily recovered by changing the temperature and recycled four times with high catalytic activity.

Preparation and adsorption properties of laponite–cyclodextrin complex

Abstract Laponite–cyclodextrin complex was synthesised by amidation of carboxylated cyclodextrin and amine-modified laponite, which were first modified by amine-terminated silane coupling agents with different chain lengths and functional groups. The structures of the laponite before and after modification were characterised by Fourier transform infrared and proton nuclear magnetic resonance. The effect of the silane coupling agents on the loading amounts of cyclodextrin onto laponite was investigated by thermogravimetric analyser. The results showed that the loading amounts of cyclodextrin and silane coupling agents increased with the increasing chain lengths and the decreasing alkoxyl groups of silane coupling agents. The laponite–cyclodextrin complexes gathered the advantages of adsorbing aromatic organic compounds by cyclodextrin via host–guest inclusion interaction and adsorbing metal ions by laponite via ion exchange. The laponite–cyclodextrin complex presents great applications in the aspect of wastewater treatment.

Synthesis and biocompatibility of phosphoryl polymer and relationship between biocompatibility and water structure

A series of copolymers, poly(methylmethacrylate-co-2-methacryloyloxyethyl phosphorylcholine), with various compositions of methyl methacrylate (MMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) were synthesized by radical copolymerization in a mixed solvent of ethanol and chloroform. The structures of the copolymers were confirmed by proton nuclear magnetic resonance and elemental analysis. The properties and morphologies of the copolymers were characterized by differential scanning calorimeter, scanning electron microscopy, and optical microscope. The adsorption of bovine serum albumin (BSA) and the adhesion of platelet on the surfaces of the copolymer membrane significantly decreased with increasing the MPC composition. The copolymers containing MPC above 18% showed excellent biocompatibility. Moreover, the relationship between the water structure and the biocompatibility was illustrated by changing quantity of the MPC in copolymers. The result showed that the amount of free water affected the platelet compatibility of the copolymer.