-
[show abstract]
[hide abstract]
ABSTRACT: Taking advantage of the condensation between Si–OH of the hydroxylated octadecyltrichlorosilane (OTS) and C–OH on graphene oxide (GO) surface, we grafted OTS onto the GO-based dual-layer film, which was composed of GO outerlayer and (3-aminopropyl)triethoxysilane (APTES) self-assembled underlayer, on a Si substrate. Thus, a hydrophobic trilayer film coded as APTES-GO-OTS was prepared successfully. To confirm the chemical composition, structure, and morphology of the trilayer film, various means including water contact angle measurement, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrometry, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) were performed. Moreover, to investigate the tribological performances, the micro- and macrotribological experiments were conducted with AFM and a UMT tribometer. The results showed that the as-prepared trilayer film exhibited low adhesion and greatly reduced the friction force in both the micro- and macroscale. Therefore, such a trilayer film is suitable for an application in the lubrication and protection of nano/microelectromechanical systems (NEMS/MEMS).
05/2011;
-
04/2011; , ISBN: 978-953-307-206-7
-
[show abstract]
[hide abstract]
ABSTRACT: Reduced graphene oxide (RGO) sheets were covalently assembled onto silicon wafers via a multistep route based on the chemical adsorption and thermal reduction of graphene oxide (GO). The formation and microstructure of RGO were analyzed by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, and water contact angle (WCA) measurements. Characterization by atomic force microscopy (AFM) was performed to evaluate the morphology and microtribological behaviors of the samples. Macrotribological performance was tested on a ball-on-plate tribometer. Results show that the assembled RGO possesses good friction reduction and antiwear ability, properties ascribed to its intrinsic structure, that is, the covalent bonding to the substrate and self-lubricating property of RGO.
Langmuir 10/2010; 26(20):15830-6. · 4.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Zirconia/polydopamine (ZrO2/PDA) nanocomposite multilayer films were constructed on Si substrate via a novel nonelectrostatic layer-by-layer (NELBL) assembly technique. The building block of this technique is the newly reported dopamine molecule, which can be attached to almost all material surfaces and undergo oxidation-polymerization to form PDA layers; more importantly, the outer hydroxyl groups of the PDA layer can chelated with certain inorganic oxide nanoparticles to generate oxide films. Thus, ZrO2/PDA nanocomposite multilayer films were fabricated by sequential NELBL deposition of PDA and ZrO2 nanoparticles. The formation of the ZrO2/PDA nanocomposite multilayer films was monitored by the water contact angle (WCA) and ellipsometric thickness measurements, while the microstructure of the fabricated films was analyzed by means of atomic force microscope (AFM), field emission scanning electron microscope (FESEM), X-ray photoelectron spectrum (XPS), and X-ray diffraction (XRD) analysis. The mechanical and anticorrosion behaviors of the annealed ZrO2/PDA nanocomposite multilayers were found to be greatly enhanced as compared with that of the annealed homogeneous ZrO2 film. The better mechanical and anticorrosion behaviors of the annealed ZrO2/PDA nanocomposite multilayers than the annealed homogeneous ZrO2 film may be closely related to their special microstructure. Namely, the organic–inorganic hybrid microstructure of the annealed ZrO2/PDA nanocomposite multilayers may largely account for the increased nanohardness and corrosion resistance. Copyright © 2010 John Wiley & Sons, Ltd.
Surface and Interface Analysis 06/2010; 43(4):803 - 808. · 1.18 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: At the room temperature, a novel and environmental friendly approach for synthesizing polyaniline (PANI) nanofibers on a large scale is presented firstly in the aqueous phase by ultraviolet (UV)-assisted polymerization using cetyltrimethylammonium bromide (CTAB) as the "soft-template." It is obvious that the polymerization process can be accelerated under the illumination of UV light and the preliminary mechanism has been pointed out. Furthermore, it also can be noted that the lower concentrations of CTAB and HCl are helpful for the fabrication of smooth and uniform PANI nanofibers. As observed with FE-SEM and TEM, the as-synthesized PANI nanostructures under the appropriate conditions are composed of uniform nanofibers with the average diameter of about 100 nm and the length of several micrometers. Subsequently, the synthesized PANI nanostructures are characterized with UV-vis, FT-IR, XRD spectra, and the typical physical and chemical properties of PANI are displayed. In addition, the conductivity of the synthesized PANI nanofibers was also measured with the four probe method and the excellent conductivity was presented. In summary, the procedure presented here only involving exposure of an acidic aqueous solution of aniline to UV light illumination is so simple and the needed equipment is so low cost, from the viewpoint of technological applications, that the large-scale UV-assisted polymerization of PANI nanofibers from the monomer solution is feasible and promising.
Journal of Nanoscience and Nanotechnology 02/2010; 10(2):933-40. · 1.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A novel 3-layer organic film was fabricated on silicon wafer with a polydopamine coating (coded as PDAc) as the interlayer by a multistep self-assembly process. The formation and structure of the films were analyzed by means of ellipsometric thickness measurement, water contact angle measurement, and attenuated total reflection-Fourier transform infrared spectrometry (ATR-FTIR). Meanwhile, an atomic force microscope (AFM) characterization was performed to evaluate the adhesive and microtribological behaviors of the 3-layer film, and a ball-on-plate tribometer was used to test macrotribological performance. As results show, the as-prepared 3-layer film possessed the excellent tribological properties characterized by lower friction and higher antiwear ability, which was ascribed to the special chemical structure of the film, i.e., the strong adhesion of the film to the silicon wafer, the chemical bonding between the adjacent layers, the cross-linked structure of the PDAc interlayer, and the hydrophobicity, high flexibility, and high elasticity of the stearoyl chloride (STC) outer layer. Hopefully, the present work provides a feasible route to construct a multilayer film with excellent structural stability and tribological behavior. The titled multilayer film might find potential applications in boundary lubrication and many other areas.
11/2009;
-
[show abstract]
[hide abstract]
ABSTRACT: Titanium oxide (TiO(2)) films were successfully deposited onto the polymer substrates of polytetrafluoroethylene (PTFE), polyethylene (PE), and polyethylene terephthalate (PET), which were pre-modified with polydopamine coating (polydopamine and its coating are coded as PDA and PDAc, respectively), by a simple liquid phase deposition (LPD) process. The morphology and chemical state of the obtained TiO(2) films were characterized by field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Subsequently, the biocompatibility of the samples was investigated by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay and acridine orange staining of MC-3T3 osteoblast cells, and the results demonstrated that the fabricated TiO(2) films could markedly improve the in vitro cytocompatibility. So, the presented route is anticipated to be a promising surface modification methodology to improve the practical outcome of the implanted materials for its versatility and validity.
Colloids and surfaces. B, Biointerfaces 10/2009; 76(1):123-7. · 2.60 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Nanocomposite films of platinum nanoparticle-deposited expandable graphene sheet (Pt/EGS) are fabricated on conductive indium tin oxide glass electrodes via a “green” electrochemical synthetic route involving a series of electrochemical processes. The microstructure and morphology of the prepared film samples are characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, three-dimensional non-contact surface mapping, and field emission scanning electron microscopy. At the same time, the catalytic activity and stability of the Pt/EGS film for the oxidation of methanol are evaluated through cyclic voltammetry and chronoamperometry tests. The Pt nanoparticles in the Pt/EGS nanocomposite film are found to be uniformly distributed on the EGS. The as-synthesized Pt/EGS nanocomposite exhibits high catalytic activity and good stability for the oxidation of methanol, which may be attributed to its excellent electrical conductivity and the high specific surface area of the graphene sheet catalyst support.
Journal of Power Sources.
-
[show abstract]
[hide abstract]
ABSTRACT: Considering for the potential application in tissue engineering, polyaniline (PANi) film was fabricated via a two-step route: a self-assembled monolayer of C6H5NHC3H6Si(OMe)3 was firstly formed on the single-crystal Si substrate; the conducting PANi film was then prepared through electroless surface polymerization of the aniline molecules on the aniline monolayer-bearing silane surface in an acidic aqueous solution. The formation of PANi film on Si surface was confirmed by characterizations of X-ray photoelectron spectroscope (XPS) and specular reflectance Fourier transform infrared (SR-FTIR) spectrum, etc. At last, the proliferation behaviors of PC-12 cells on the PANi film surface were studied by the [3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) colorimetric assays, acridine orange fluorometric staining, and scanning electron microscope (SEM) observation, etc. The results demonstrate that the as-prepared PANi film provides high ability for cell proliferation, exhibiting promising potentials as surface coating to cultivate neuronal cells for applications in the tissue engineering.
Applied Surface Science 256(11):3427-3431. · 2.10 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Mesoporous bioactive glass (MBG) of CaO–SiO2–P2O5 was synthesized using nonionic block copolymer (EO20PO70EO20, P123) and acetic anhydride as the template and catalyst, respectively. It was inferred that acetic anhydride could accelerate the hydrolysis of tetraethyl orthosilicate and the obtained by-product of acetic acid was harmless to the environment. The TEM analysis indicated that the synthesized MBG had two-dimensional (2D) hexagonal mesostructures, and the measured BET surface area, pore volume and pore diameter were 499 m2/g, 0.70 cm3/g and 6.1 nm, respectively. Moreover, the synthesized MBG showed an excellent bioactivity in vitro as assessed by immersion studies in simulated body fluid (SBF). In a word, this work presents a simple and environment friendly route for synthesizing MBG by use of acetic anhydride as the catalyst and would find potential applications in tissue engineering and other fields.
Journal of Non-Crystalline Solids 356:1514-1518. · 1.54 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A polydopamine coating (coded as PDAc) was prepared successfully on a Si substrate through a two-step process. Briefly, to improve the adhesion of PDAc on the Si substrate, a self-assembled monolayer of 3-aminopropyl triethoxysilane (coded as APTS-SAM) was firstly generated on the bare Si wafer. Thereafter, the PDAc with different thickness was fabricated through the chemical adsorption and autopolymerization of the dopamine hydrochloride on the APTS-SAM coated Si substrate. The formation of PDAc on the APTS-SAM modified Si substrate was proved by the characterizations of contact angle measurement, attenuated total reflectance Fourier transform infrared (ATR-FTIR) analysis, and X-ray photoelectron spectroscope (XPS), etc. The ellipsometric thickness measurement and atomic force microscopy (AFM) image analysis showed that the PDAc became thicker and rougher with the deposition time prolongation. Microtribological study showed that the thickness and roughness of the PDAc played a significant role in the tribological properties. In comparison with the bare Si substrate, the PDAc with thinner thickness possessed lower friction and was anticipated to be used as protecting coating in the field of boundary lubrication. The electrochemical corrosion behaviors of the prepared PDAc were investigated using the electrochemical station and a low corrosion current density was revealed, implying that the PDAc had good anti-corrosion capability and might find potential applications in the field of corrosion resistance.
Applied Surface Science 256(3):894-899. · 2.10 Impact Factor
