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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: An epoxy resin was used to prepare crosslinked polyurethane hybrid emulsion through the blocked NCO prepolymer mixing process.
Due to their hydrophobicity, the amine chain extender, blocked –NCO, and epoxy are located inside the emulsion particles.
Thus, the crosslinking reaction occurs mostly in the interior of the particles. In this way, the crosslinking density of the
resin is increased without the use of solidifying agents or heating during film formation, and the stability of the emulsions
remains uninfluenced. The effects of the type of amine chain extender and the type, dosage, and addition mode of the epoxy
resin were studied in terms of mechanical properties and swelling properties in water and toluene of the cast films. Additionally,
the stability of the single-pack hybrid emulsion was studied. The results showed that the sample prepared with diethylene
triamine had good stability, chemical resistance, and high mechanical strength. The modulus and water resistance of the films
increased with the epoxy resin content, which could reach 20wt%. The type of amine chain extender affected the stability
of the emulsions significantly. The molar ratio of NH/NCO at 1:1 led to the best film performance. The optimal temperature
of the chain-extension reaction was approximately 80°C. The hybrid emulsions could be stored for at least 6months without
apparent performance changes.
KeywordsCrosslinking-Epoxy resin-Polyurethanes emulsion
Journal of Coatings Technology and Research 05/2012; 7(3):373-381. · 1.12 Impact Factor
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ABSTRACT: Fluorine-containing poly-styrene-acrylate (PSA) latex with core–shell structure was successfully synthesized by seeded semicontinuous
emulsion polymerization using fluorine monomer Actyflon-G04 and reactive emulsifier DNS-86. The chemical composition, morphology of latex, and surface composition of the latex film
were characterized by Fourier transform infrared spectra, transmission electron microscopy, and X-ray photoelectron spectroscopy,
respectively. The stability properties of latex were tested by Ca2+, centrifugal and mechanical stability tests, and the latex film was studied by water contact angle, water absorption ratio,
and thermo-gravimetric analysis. The results show that fluorine-containing PSA latex particles with crosslinked core and crosslinked
shell structure have excellent stability properties, and the film of latex has excellent water repellency, thermal stability,
and chemical resistance properties when the amount of fluorine monomer was only 8.0wt%.
KeywordsCore–shell–Fluorine-containing–Styrene-acrylate latex–Reactive surfactant
Journal of Coatings Technology and Research 04/2012; 8(3):401-407. · 1.12 Impact Factor
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ABSTRACT: Mesoporous titania-grafted poly(styrene-divinylbenzene)/maleic anhydride [P(St-DVB)/MA] nanocomposite microspheres were prepared
by an open ring reaction method. The titania nanoparticles were first modified by attachment of amino groups to their surface
to prevent particle aggregation, and to allow the nanoparticles to covalently bond the polymer microspheres, the surface of
which was modified by attachment of MA functional groups to enable the polymer to retain their porous structures and to react
with the amino groups on the surface of the titania particles. The porous nanocomposite microspheres were detected by FTIR,
SEM, TEM, XRD and UV-Vis spectrophotometry. The results indicated that the nanocomposite microspheres were composed of nanosized
titania uniformly distributed on the surface, and exhibited better UV absorbing property than pure polymer microspheres or
unmodified titania. Furthermore, compared with pure porous polymer microspheres, the nanocomposite microspheres showed more
efficient UV protection and slow release of Parsol-1789 (a photo-reactive and cosmetic agent) held inside the porous network
of the microspheres.
Keywordsporous-titania-poly(styrene-divinylbenzene)-maleic anhydride-nanocomposite
Science China-Chemistry 04/2012; 53(3):605-611. · 1.02 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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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: BACKGROUND: To create a hydrophobic surface, a commonly used two-step process is the formation of a rough surface and its subsequent modification with materials of low surface energy. Here, a new method for making a hydrophobic surface is proposed using emulsion copolymerization with a low-surface-energy fluoropolymer in the presence of a high percentage of silica particles creating a well-spread roughness.RESULTS: Irregular core–shell structural composite particles such as of snowman shape and sandwich shape were obtained and characterized. The hydrophobicity and chemical structure of the hybrid film were investigated. It was found that strong inter- and intramolecular chemical bonding in the composite film may improve the properties of the hybrid film. Enrichment of fluorine on the film surface and well-distributed roughness due to the silica particles covered by the fluoropolymer contribute to the increased hydrophobicity of the film. The water contact angle on the film increased from 106 ± 2° to 135 ± 2°.CONCLUSION: The stable core–shell hybrid latex synthesized in this work will be of use in preparing high-performance hydrophobic aqueous coatings. Copyright © 2008 Society of Chemical Industry
Polymer International 10/2008; 57(11):1287 - 1294. · 1.90 Impact Factor
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ABSTRACT: Nanoparticles of hydroxyapatite(HAP), strontium half substituted hydroxyapatite (SrCaHAP) and strontium totally substituted
hydroxyapatite (SrHAP) were prepared by sol-gel-supercritical fluid drying (SCFD) method. The nanoparticles were characterized
by element content analysis, FT-IR, XRD and TEM, and the effects of strontium substitution on crystal structure, crystallinity,
particle shape and antibacterial properties of the nanoparticles on Escherichia coli, Staphylococcus aureus, Lactobacillus
were researched. Results show that strontium can half and totally substitute for calcium and enter the structure of apatite
according to the initial atomic ratios of Sr/[Sr+Ca] as 0.5, 1. The substitution decreases the IR wavenumbers of SrCaHAP and
SrHAP, and changes the morphology of the nanoparticles from short rod shaped HAP to needle shaped SrCaHAP, and back to short
rod shaped SrHAP. The crystallinity of HAP is higher than that of SrCaHAP, but is lower than that of SrHAP. Moreover, the
antibacterial property of SrCaHAP and SrHAP are improved after the calcium is half and totally substituted by strontium.
Journal of Wuhan University of Technology-Mater Sci Ed 07/2008; 23(4):475-479. · 0.35 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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ABSTRACT: Fluoropolymer and different kinds of silica particles were used for controlling surface chemistry and morphology, respectively. A superhydrophobic surface originated from strawberry-like or quincunx-shaped composite silica particles was obtained. The dual size particles are obtained by utilizing the graft of different modified silica particles with epoxy functional group and amine functional group. This makes the surface of film form a composite interface to have irregular binary structure which plays an essential role in trapping air between the substrate surface and the liquid droplets to be necessary for high contact angle and low contact angle hysteresis. The maximum contact angle for water on the hybrid film is about 174±2 • and the contact angle hysteresis is less than 2 • . The surface morphologies, roughness and the wettability on the surface of films containing different structural silica particles were compared. It was shown that the hierarchical irregularly structure with a low roughness factor and high air-trapped ratio is indispensable for superhydrophobic surface. Although this structural surfaces based on composite silica particles play a vital role in governing the surface wettability, it is necessary to combine with a low surface energy to make the surface superhydrophobic.
J. Mater. Sci. Technol. 01/2008; 24.
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ABSTRACT: The microwave-assisted extraction (MAE) technology of skin-lightning agent in Rhizoma Typhonii was studied and the relative inhibitory activity of the extract against tyrosinase was used as evaluating criterion. It was concluded that the optimal condition was two doses of microwave radiation (450 W) for 7 min with a mass ratio of water to material of 10: 1. The dry extract of Rhizoma Typhonii with 20.9% yield and 47.1% relative inhibitory activity against tyrosinase was obtained. Compared with direct-heating extraction, MAE can shorten extracting duration, and improve relative inhibitory activity of the extract against tyrosinase.
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials 12/2004; 27(11):863-6.
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POLYMER–PLASTICS TECHNOLOGY AND ENGINEERING Vol. 43. 01/2004; No. 5(pp. 1459–1469):1459-1469.
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ABSTRACT: The laponite pillared by the CeO2 modified TiO2 (Ce-Ti-lap) were prepared by microwave intercalation reaction with laponite as the layered clay, tetrabutyl titanate and cerium chloride as the Ce-Ti composite pillaring agent, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brumauer-Emmett-Teller (BET) surface area. The photocatalytic activities of Ce-Ti-lap were investigated by the degradation of methyl orange (MO). The results showed that Ce and Ti could be introduced to the interlayers of laponite, and the CeO2 modified TiO2 pillared structures could be formed with the basal spacing and the BET surface area of Ce-Ti-lap significantly increased. The Ce-Ti-lap showed the best photocatalytic activity in the degradation of MO compared with the pure TiO2, the laponite only pillared by TiO2 (Ti-lap) and the laponite only pillared by CeO2 (Ce-lap). Using the Ce-Ti-lap with the mass fraction of Ce/Ti (XCe) of 0.05, under the conditions of the initial concentration of MO 20 mg/L, irradiation time 120 min, pH value 4, photocatalyst dosage 1.5 g/L, the decoloring rate of MO achieved 96.3%, which decreased only 3.9% after being used 5 times, indicating that the Ce-Ti-lap had excellent photocatalytic activity and active stability.
Journal of Rare Earths 28(5):732-736. · 0.90 Impact Factor
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ABSTRACT: Functional porous microspheres used for the slow release carrier of actives in cosmetics or pharmaceuticals were prepared by modified suspension polymerization of styrene (ST) with divinylbenzene (DVB) in the presence of toluene, cyclohexanol and heptane as porogenic diluents. The use of ultrasonic dispersion decreases the beads' size and improves the uniformity. The effects of the porogen mixture, DVB content and solvent extraction on the surface performance of the synthesized beads were studied. The microspheres were characterized by scanning electron microscopy (SEM) and BET surface area determination. It was found that a great proportion of the non-solvating porogen increases the pore diameter and the specific surface area. High DVB concentration also results in the great specific surface area and porosity. When the ratio of toluene/cyclohexanol is 1:2, DVB content is at the range of 40%–60% and methylene chloride was used as extractant, the beads with good spherical shape and pore size were obtained. The prepared porous microspheres were applied as active carriers and showed satisfactory slow release effect. Over 10h constantly sustained release was observed in vitro releasing test for hydroquinone-loaded microspheres. Great surface area promoted high concentration of released hydroquinone.
Chinese Journal of Chemical Engineering. 14(4):471-477.
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ABSTRACT: Inorganic–organic hybrid latex containing fluoride has been prepared in multistage emulsion polymerization in the presence of nano-SiO2 particles and alkoxysilane (γ-methacryloxypropyltri(isopropoxy)silane, MAPTIPS). The effects of fluoride and alkoxysilane on the morphologies of composite particles were observed and it was found that the encapsulation may be fulfilled in the presence of dodecafluoroheptyl methacrylate together with MAPTIPS whether using raw SiO2 particles or modified. The distribution of fluorine in different latex films was measured by X-ray photoelectron spectroscopy. It was indicated that the gradient distribution of fluorine from depth profile in the films may be enhanced by MAPTIPS and encapsulated SiO2 due to the bidirectional move of MAPTIPS and congregation of SiO2 on the film surface. Combining the results of XPS with AFM analysis, it was showed that the phase separation between organic and inorganic for encapsulated SiO2 was lightened, while it was so apparent for raw SiO2 that the orientation to the surface of fluorine was restrained in the lack of MAPTIPS.
Colloids and Surfaces A Physicochemical and Engineering Aspects 345:18-25. · 2.24 Impact Factor
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ABSTRACT: I n recent years, the application of high-density multi-layer circuit boards in electronic products has put forward more set of requirements, especially on the thermal stability of the insulation ink, as the key material in the manufacturing of printed circuit board (PCB). Both o-cresol formaldehyde epoxy (OCFEP) and cyanate ester (CE) resins show outstanding thermal stability for application in PCB. In this work, cyanate prepolymer (PCE) and a PCE/OCFEP composite system were prepared. The curing behaviour of cyanate prepolymer/o-cresol formaldehyde epoxy resin system was studied with non-isothermal differential scanning calorimetry (DSC). Combined with the application requirement, the curing process of the system was determined as: 130°C/1h+140°C/1h+180°C/1h. The DSC results also revealed that the apparent activation energy of curing reaction was 83.22, 66.32 and 78.48 kJ/mol when PCE content was 80, 60 and 40 wt%, respectively. This indicates that there was an optimal proportion of PCE and OCFEP in the system. The curing kinetics followed the first order reaction. Theoretical analysis on the curing proccess of the system with 60 wt% PCE showed that the thermal stability increased with increased post-processing temperature. This study could provide some guides and basic data for the development of insulation ink for high-density multi-layer printed circuit boards.
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ABSTRACT: A superhydrophobic surface originated from quincunx-shape composite particles was obtained by utilizing the encapsulation and graft of silica particles to control the surface chemistry and morphology of the hybrid film. The composite particles make the surface of film form a composite interface with irregular binary structure to trap air between the substrate surface and the liquid droplets which plays an essential role in obtaining high water contact angle and low water contact angle hysteresis. The water contact angle on the hybrid film is determined to be 154 ± 2° and the contact angle hysteresis is less than 5°. This is expected to be a simple and practical method for preparing self-cleaning hydrophobic surfaces on large area.
Applied Surface Science.
