Synergetic Research Center on Advanced Materials

Nanjing, China

Synergetic Research Center on Advanced Materials

Nanjing, China
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Shi Y.,Nanjing University of Science and Technology | Xiong D.,Nanjing University of Science and Technology | Xiong D.,Jiangsu Key Laboratory of Advanced Micro and Nano Materials and Technology | Li J.,Nanjing University of Science and Technology | Wang N.,Synergetic Research Center on Advanced Materials
Journal of Physical Chemistry C | Year: 2016

Graphene-oxide-containing poly(vinyl alcohol) (PVA/GO) composites prepared by the freeze-thaw method were irradiated by γ-rays at doses of 50, 100, 150, and 200 kGy to improve their strength and wear resistance. The effects of irradiation dose on the mechanical, thermal, and tribological properties were evaluated. The microstructure and composition of the PVA/GO hydrogels before and after irradiation were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results reveal that the irradiation can reduce the GO sheets dispersed in the PVA matrix in situ and that the reduced graphene oxide acts as the cross-linking point of the dangling bonds between molecular chains and forms covalent bonds after γ-ray irradiation, which endows the composites with high strength and improved thermal stability. Compared to the nonirradiated PVA/GO hydrogels, a 270% enhancement in compressive strength was obtained when the applied irradiation dose was 150 kGy. The friction coefficient of the PVA/GO hydrogels increased with increasing irradiation dose because of the loss of hydrophilicity. However, the wear resistance significantly improved upon irradiation treatment. © 2016 American Chemical Society.


Wang N.,Nanjing University of Science and Technology | Wang N.,Jiangsu Key Laboratory of Advanced Micro nano Materials and Technologies | Wang N.,Synergetic Research Center on Advanced Materials | Xiong D.,Nanjing University of Science and Technology | And 6 more authors.
Applied Surface Science | Year: 2015

A superhydrophobic surface (SHS) was prepared on steel via the synergetic corrosion of H2O2 and H2SO4, followed by the modification of silanes. Flower-like hierarchical structures were obtained by the following two etching aspects: the non-uniform ions concentration around O2, and the selective corrosion for steel substrate. Surface grafting was manifested to preferentially be realized on the oxidized area, and the H2O2 is crucial for the grafting efficiency. Moreover, the resultant surface exhibited superior anti-icing property in extremely condensing condition. In addition, surface with C-F bond exhibited outstanding UV-durability. © 2015 Elsevier B.V. All rights reserved.


Qin Y.,Nanjing University of Science and Technology | Qin Y.,Key Laboratory of Advanced Micro Nano Materials and Technology | Qin Y.,Synergetic Research Center on Advanced Materials | Xiong D.,Nanjing University of Science and Technology | And 4 more authors.
Applied Surface Science | Year: 2015

Laser surface-textured Ti6Al4V substrate was treated by plasma electrolytic oxidation process to prepare an oxide ceramic coating and then burnished with a thin MoS2 film. The area densities of textured dimples and the surface roughness of oxide ceramic underlay which affected the longevity of MoS2 films were thoroughly investigated. The results showed that a mixed surface pattern combining large textured dimples (diameter 150 μm) with small discharged dimples (diameter 5-17 μm) was fabricated by the LST/PEO duplex treatment and it contributed to prolonging the lubricating life of MoS2 film in comparison to the LST or PEO treatment. Wherein, the mixed dimples acted as lubricant reservoirs and the hard oxide coatings provided high load supports for the lubricating films. A much longer life of low friction was provided by the LST/PEO/MoS2 coatings with higher density of textured dimples (S = 55%) and lower roughness of LST/PEO surface (Ra = 1.0 μm). © 2015 Elsevier B.V. All rights reserved.


Shi Y.,Nanjing University of Science and Technology | Xiong D.S.,Nanjing University of Science and Technology | Xiong D.S.,Jiangsu Key Laboratory of Advanced Micro nano Materials and Technology | Xiong D.S.,Synergetic Research Center on Advanced Materials | And 2 more authors.
Express Polymer Letters | Year: 2016

Poly (vinyl alcohol)/poly (vinyl pyrrolidone) (PVA/PVP) hydrogels with various polymerization degrees of PVA were synthesized by a repeated freezing-thawing method. The influence of polymerization degree on microstructure, water content, friction coefficient, compressive fatigue and recovery properties of PVA/PVP hydrogels were investigated. The results showed that higher polymerization degree resulted in larger compressive modulus and lower friction coefficient. The fatigue behaviors of PVA/PVP hydrogels were evaluated under sinusoidal compressive loading from 200 to 800 N at 5 Hz for up to 50 000 cycles. The unconfined uniaxial compressive tests of PVA/PVP hydrogels were performed before and after fatigue test. During the fatigue test, the height of the hydrogel rapidly decreased at first and gradually became stable with loading cycles. The compressive tangent modulus measured 0 h after fatigue was significantly larger than the values obtained before test, and then the modulus recovered to its original level for 48 h after test. However, the geometry of hydrogels could not return to the original level due to the creep effects. PVA/PVP hydrogels prepared with lower polymerization degree showed better recovery capability than that prepared with high polymerization degree. © BME-PT.


Wang N.,Nanjing University of Science and Technology | Wang N.,Jiangsu Key Laboratory of Advanced Micro Nano Materials and Technologies | Wang N.,Synergetic Research Center on Advanced Materials | Xiong D.,Nanjing University of Science and Technology | And 5 more authors.
ACS Applied Materials and Interfaces | Year: 2015

A superhydrophobic steel surface was prepared through a facile method: combining hydrogen peroxide and an acid (hydrochloric acid or nitric acid) to obtain hierarchical structures on steel, followed by a surface modification treatment. Empirical grid maps based on different volumes of H2O2/acid were presented, revealing a wettability gradient from "hydrophobic" to "rose effect" and finally to "lotus effect". Surface grafting has been demonstrated to be realized only on the oxidized area. As-prepared superhydrophobic surfaces exhibited excellent anti-icing properties according to the water-dripping test under overcooled conditions and the artificial "steam-freezing" (from 50 °C with 90% humidity to the -20 °C condition) test. In addition, the surfaces could withstand peeling with 3M adhesive tape at least 70 times with an applied pressure of 31.2 kPa, abrasion by 400 grid SiC sandpaper for 110 cm under 16 kPa, or water impacting for 3 h without losing superhydrophobicity, suggesting superior mechanical durability. Moreover, outstanding corrosion resistance and UV-durability were obtained on the prepared surface. This successful fabrication of a robust, anti-icing, UV-durable, and anticorrosion superhydrophobic surface could yield a prospective candidate for various practical applications. © 2015 American Chemical Society.

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