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Ji X.,Shanxi Research Institute of Applied Chemistry | Zhang X.,Texas Tech University | Zhang X.,Hefei University of Technology
Journal of Nanomaterials | Year: 2015

In recent years, three-dimensional (3D) graphene-based nanomaterials have been demonstrated to be efficient and promising electrocatalysts for oxygen reduction reaction (ORR) in fuel cells application. This review summarizes and categorizes the recent progress on the preparation and performance of these novel materials as ORR catalysts, including heteroatom-doped 3D graphene network, metal-free 3D graphene-based nanocomposites, nonprecious metal-containing 3D graphene-based nanocomposites, and precious metal-containing 3D graphene-based nanocomposites. The challenges and future perspective of this field are also discussed. © 2015 Xuan Ji et al. Source


Wu J.,Taiyuan University of Technology | Wu J.,Shanxi Research Institute of Applied Chemistry | Xie J.,Taiyuan University of Technology | Ling L.,Taiyuan University of Technology | And 2 more authors.
Journal of Coatings Technology Research | Year: 2013

This paper describes surface modification of commercial nanosilica with 3-mercaptopropyl trimethoxysilane (MPTMS) and its effect on the properties of UV curable coatings. The mercapto groups were grafted onto nanosilica surface by a condensation of the surface Si-OH with the hydrolysized Si-OH of MPTMS. Fourier transform infrared spectroscopy, thermal gravimetric analysis, and particle size distribution were employed to characterize nanosilica and modified nanosilica. It was demonstrated that the mercapto groups were successfully grafted onto the nanosilica surface with the grafting ratio of 16.8% and the mercapto groups content of 0.9 mmol/g. The dispersion and self-aggregation of nanosilica in UV curable coatings were improved significantly. The photopolymerization kinetics of UV curable coatings, containing various amounts of nanosilica and modified nanosilica, were evaluated by the photo differential scanning calorimetry technique. This indicated that nanosilica both before and after modification decreased UV curing speed and ultimate percentage conversion; however, in comparison with the coatings containing unmodified nanosilica, the coatings containing modified nanosilica exhibited higher curing speeds and conversion ratios. It can be ascribed that the mercapto groups on the nanosilica surface reduced oxygen inhibition during the UV curing process via the thiol-ene click reaction. The mechanical properties of UV curable coatings were also compared. © 2013 American Coatings Association & Oil and Colour Chemists' Association. Source


Wu J.,Taiyuan University of Technology | Wu J.,Shanxi Research Institute of Applied Chemistry | Ling L.,Taiyuan University of Technology | Ma G.,Shanxi Research Institute of Applied Chemistry | Wang B.,Taiyuan University of Technology
Journal of Coatings Technology Research | Year: 2014

Nanosilica was modified and functionalized with acrylsilane by the "grafting to" method via different grafting steps, i.e., prepared-grafting step and step-wise propagation. The prepared-grafting step was achieved by grafting the nanosilica surface with the prepared acrylsilane, which was obtained by thiol-ene click reaction between 3-mercaptopropyl trimethoxysilane (MPTMS) and trimethylolpropane triacrylate (TMPTA). The step-wise propagation was achieved by first grafting MPTMS onto the nanosilica surface and then using the mercapto groups as initiators to react with TMPTA. The acrylsilane was characterized by FTIR. The modified nanosilica was characterized by FTIR, TGA, and contact angle analysis. It was demonstrated that the thiol-ene click reaction can easily occur between MPTMS and TMPTA. The grafting ratio of modified nanosilica via prepared-grafting step was higher than that of step-wise propagation. The SEM images of fractured films containing modified nanosilica also indicated that the former is more effective than the latter in reducing the self-aggregation of nanosilica. The effects of modified nanosilica on the viscosity and hardness of UV-curable coatings were also investigated. © 2014 American Coatings Association. Source


Wu J.,Taiyuan University of Technology | Wu J.,Shanxi Research Institute of Applied Chemistry | Ma G.,Shanxi Research Institute of Applied Chemistry | Ling L.,Taiyuan University of Technology | Wang B.,Taiyuan University of Technology
Polymer Bulletin | Year: 2015

The nanosilica is first treated with 3-mercaptopropyl trimethoxysilane (MPTMS) to introduce mercapto groups as growth points, and then hyperbranched polymer is grafted on the nanosilica surface via repeated step of thiol-ene click reaction between the acrylate double bond of trimethylolpropane triacrylate (TMPTA) and mercapto groups of trimethylolpropane tris 3-mercaptopropionate (Trithiol). FTIR results confirm that the grafting procedure is feasible, and TGA results indicate the grafting ratio is as high as 45.0 %. The curing kinetic, monitored by photo-DSC, shows that both terminal acrylate double bonds and mercapto groups can accelerate the curing speed of the UV-curing organic–inorganic hybrid coatings. The mechanical and physical properties of UV-curable hybrid coatings containing modified nanosilica at different generations are also investigated. © 2015 Springer-Verlag Berlin Heidelberg Source


Wu J.,Taiyuan University of Technology | Wu J.,Shanxi Research Institute of Applied Chemistry | Ling L.,Taiyuan University of Technology | Xie J.,Taiyuan University of Technology | And 2 more authors.
Chemical Physics Letters | Year: 2014

Surface modification of nanosilica with 3-mercaptopropyl trimethoxysilane (MPTMS) has been investigated. FTIR, TGA, CA, 29Si NMR and DFT method have been applied to study the interaction between nanosilica and MPTMS. The results show that the organic functional groups are successfully grafted onto the nanosilica surface and the grafting ratio firstly increases and then decreases with the increasing MPTMS. In addition, four different grafting modes between nanosilica surface and MPTMS have been studied by DFT method. It indicated that the favorable grafting structures are mono-, di-grafting mode when the MPTMS is lower and ladder-like grafting mode when the MPTMS is higher. © 2013 Elsevier B.V. All rights reserved. Source

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