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ABSTRACT: This article describes a high efficient and economical method to synthesize a liquid crystalline epoxy resin (LCER) containing
biphenol and aromatic ester group, 3,3′,5,5′-tetramethylbiphenyl-4,4′-diyl bis(4-(oxiran-2-ylmethoxy) benzoate) (4). First, 3,3′,5,5′-tetramethylbiphenyl-4,4′-diyl bis(4-hydroxybenzoate) (3) was prepared by direct esterification of 3,3′,5,5′-tetramethylbiphenyl-4,4′-diol (2) with p-hydroxybenzoic acid (1) in the presence of a certain amount of p-toluene sulfonic acid (p-TSA) as catalyst. And then (4) was synthesized by the reaction of (3) with epichlorohydrin. The chemical structure, melting range, and liquid crystalline phase transition behavior of (4) were characterized by FT-IR, 1H-NMR, 13C-NMR, mass spectroscopy, differential scanning calorimetry (DSC), and polarized optical microscopy (POM).
KeywordsLiquid crystalline epoxy resin–Synthesis–Esterification–Cure behavior
Polymer Bulletin 05/2012; 67(1):57-66. · 1.53 Impact Factor
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ABSTRACT: Encapsulated aluminum pigments were prepared by sol–gel derived inorganic–organic hybrid coatings. Aluminum pigments were
first coated with sol–gel film by using tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) as the precursor, followed
by free radical copolymerization of styrene (St), divinylbenzene (DVB) and maleic acid anhydride (MAA) with the vinyl group
of the VTES. The as-prepared encapsulated aluminum pigment was characterized by Fourier transform infrared spectroscopy (FTIR),
scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Subsequently the stability of the aluminum
pigments in alkaline aqueous media was examined. It was found that both the TEOS-and-VTES-coated (TV-coated) and the TEOS–VTES–St–DVB–MAA-coated
(TVSDM-coated) aluminum pigments were superior in the stability test over the uncoated aluminum pigments. Furthermore, the
corrosion protection efficiency of the TVSDM-coated aluminum pigments reaches 99.8%, indicating that the inorganic–organic
hybrid composite layer on the surface of the aluminum pigments can protect them well.
Journal of Coatings Technology and Research 04/2012; 5(1):77-83. · 1.12 Impact Factor
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ABSTRACT: The kinetics and mechanism of poly(phenylene ether)/epoxy resin (PPE/EP) cure system were investigated using an advanced iso-convensional method (AICM). The curing experiments of a PPE/EP cure system with different PPE/EP ratios were carried out by means of non-isothermal differential scanning calorimetry (DSC) with different heating rates of 5, 10, 15 and 20°C/min. From the DSC curves, it was shown that the curing mechanism of PPE/EP is very complicated, and PPE content affects most cure kinetic parameters. A variation of the effective activation energy with the extent of conversion was obtained by AICM and analyzed.
Polymer-Plastics Technology and Engineering 11/2011; 50(15):1515-1518. · 1.28 Impact Factor
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ABSTRACT: Developing microstructures, such as low molecular aggregates, spherical micelles and multi-compartment micelles, is an expanding area of research in Materials Science. By applying an atom transfer radical polymerization (ATRP) process to cross-linkable fluorinated diblock copolymers and analyzing the data we are able to demonstrate the potential for developing films with different micro-structures for additional biological research. Applying the Dissipative Particle Dynamic (DPD) Method, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) techniques to cross-linkable fluorinated diblock copolymers of (methyl methacrylate-co-hydroxyethyl methacrylate-co-butyl methacrylate)-b-2-(perfluoroalkyl)ethyl methacrylate (MMA-co-HEMA-co-BMA-b-FMA) we were able to analyze the structures and their relationships to the aggregation of various microstructure formations through the use of various solvents in the process. For the self-assembly of the cross-linkable diblock copolymer in solutions, the DPD simulation results are only in qualitative agreement with experimental data of aggregate morphologies and sizes. This suggests an improved approach to creating materials and methods necessary for studying microstructures in films used in other research areas. Our work examines whether using selective solvents can be easily extended to prepare aggregates with different morphologies, which is an effective shortcut to obtain films with different microstructures. DPD simulation can be considered as an adjunct to experiments and provides other valuable information for the experiment.
Physical Chemistry Chemical Physics 09/2011; 13(38):17323-32. · 3.57 Impact Factor
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Macromolecular Materials and Engineering 10/2010; 296(1):83 - 91. · 1.99 Impact Factor
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ABSTRACT: In this study, a novel and effective suspension polymerization has been employed to prepare functional magnetic porous SrFe12O19/P(St-DVB-MAA) microspheres in the presence of bilayer surfactants (sodium dodecyl benzene sulfonate (SDBS) and oleic acid
(OA)) coated on micro-size magnetic SrFe12O19. This was achieved by pre-polymerizing the organic phase, which contained co-monomers, porogens and treated magnetic particles,
at 65°C for 0.5 h under ultrasound conditions. Aqueous solutions containing a dispersion agent were then added to effect suspension
polymerization. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD),
thermogravimetric analysis (TGA) and magnetic property measurement system (MPMS) were used to characterize the functional
magnetic porous microspheres. The results show that the microparticles are well shaped with a uniform size distribution of
about 0.5 ∼ 0.7 mm and the surfaces of the microspheres have many micro-pores with an average diameter of 0.533 µm. There
are carboxyl groups (−COOH) on the surface of the microspheres to the extent of 0.65 mmol g−1, as determined by conductometric titration. According to the XRD spectra, iron oxide consists mainly of SrFe12O19 which reveals hexahedral structure. The content of magnetic SrFe12O19 reaches 17.81% (by mass), and the microspheres have good heat resistance. The magnetic porous microspheres are ferromagnetic
with high residual magnetization and coercivity, 21.59 emu g−1 and 4.13 kOe, respectively. The saturation magnetisation is around 42.85 emu g−1.
Central European Journal of Chemistry 11/2008; 6(4):627-633. · 1.07 Impact Factor
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ABSTRACT: The composite particles with core/shell structure resulting from the combination of silica seed and hydrophobic copolymer (dodecafluoroheptyl methacrylate (DFMA), gamma-methacryloxypropyltriisopropoxidesilane (MAPTIPS), methyl methacrylate, butyl acrylate) were synthesized by emulsion polymerization. The amount of the silica seeds, concentration of reactive surfactant, as well as the addition of DFMA and MAPTIPS, have strong influences on the morphology of composite particles. It has been shown that it would be possible to produce stable organic/inorganic composite particles with inhomogeneous core/shell structure encapsulated by hydrophobic fluorinated acrylate even though using unmodified silica particles and admixture of anionic and nonionic surfactants. However, there was an obvious difference on the morphologies of core-shell structure whether the DFMA and MAPTIPS were added or not. It was concluded that two kinds of polymerization approaches might coexist in the presence of DFMA and MAPTIPS for raw silica. One clear advantage of this process is that there is only one silica bead for each composite particle. This kind of stable core-shell structural hybrid latex is useful for preparing high performance hydrophobic coating.
Journal of Colloid and Interface Science 02/2008; 317(1):62-9. · 3.07 Impact Factor
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Drying Technology 02/2007; 20(3)(553–567 (2002)):553-567. · 2.08 Impact Factor
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ABSTRACT: To evaluate the effect of paeonol on the activity of tyrosinase and provide experimental evidence for the treatment of hyperpigmentation disorders.
Tyrosinase activity was estimated by measuring the oxidation rate of L-3,4-dihydroxyphenylalanine (L-Dopa). The inhibitory effects of paeonol on the activity of mushroom tyrosinase and Michaelis-Menten kinetics were deduced from the Lineweaver-Burk plots.
The inhibitory concentration of paeonol leading to 50% enzyme activity lost (IC50) was estimated to be 0.60 mmol x L(-1). The inhibition constants for paeonol binding free enzyme, K(I), and substrate-enzyme, K(IS), are 0.084 and 0.12 mmol x L(-1), respectively.
Paeonol is a potential mixed inhibitor of mushroom tyrosinase. The mixed inhibition function may originate from its ability to form a Schiff base with a primary amino group and to chelate copper at the active site of tyrosinase.
Yao xue xue bao = Acta pharmaceutica Sinica 07/2006; 41(6):561-4.
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ABSTRACT: A series of functional silica films on stainless steel meshes are fabricated by simple sol–gel process using tetraethyl orthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors and post-thermal treatment or hydrophobization. The wettabilities of these meshes can range from superhydrophobicity and superoleophilicity to superamphiphilicity or amphiphobicity. The tunable wetting states are controlled by changing surface chemistry or morphology. Firstly, methyl-endcapped silica film with superhydrophobic and superoleophilic property is formed using a dip-coating method; then, the methyl groups are removed by adequate annealing, and the mesh exhibits superamphiphilic property; finally, after surface modification by perfluorooctyltriethoxysilane, the amphiphobic mesh is obtained. These stainless steel meshes with different wettabilities may act as “smart” switches, which can allow oil or water pass through the mesh or not selectively, and this is potential to be used in intelligent oil/water separating device.Research highlights► A superhydrophobic and superoleophilic mesh was prepared by sol–gel process. ► The mesh can turn to be superamphiphilic or amphiphobic easily. ► The meshes with different wetting can be used to control oil/water separation.
Surface and Coatings Technology 205:5387-5393. · 1.87 Impact Factor
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ABSTRACT: A super-hydrophobic and super-oleophilic silica film on stainless steel mesh was obtained by simple sol–gel method using tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as precursors. The super-hydrophobic and super-oleophilic properties were achieved owing to the hierarchical structure of the silica film with methyl groups terminated domains constructed on the mesh. The effects of the particle size, molar ration of MTES/TEOS, molar concentration of TEOS and aging of the silica sol on the hydrophobicity of the silica film were discussed. With increasing the dimensional size of silica particle, molar ration of MTES/TEOS, molar concentration of TEOS and aging period, the hydrophobicity of the silica film can be enhanced due to the increase of the surface roughness or coverage of the methyl groups. Besides, diiodomethane droplet can spread out on the silica film within 6.71 s for the capillary force and intrinsic oleophilicity of the methyl groups.
Applied Surface Science.
