Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surfa...Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.展开更多
This paper describes a study on electrical resistivity under loading of polyaniline (PANI)/graphene nanocomposite powders and compacts. The composites were prepared by an in-situ interfacial dynamic inverse emulsion p...This paper describes a study on electrical resistivity under loading of polyaniline (PANI)/graphene nanocomposite powders and compacts. The composites were prepared by an in-situ interfacial dynamic inverse emulsion polymerization technique under sonication of aniline in the presence of graphene sheets in chloroform. During polymerization the graphene nanoplatelets are coated with PANI and are well dispersed both in the polymeric suspension and then in the dried polymer matrix as evidenced by cryogenic transmission electron microscopy (Cryo-TEM) and high resolution scanning microscopy (HRSEM). The presence of graphene nanoplatelets lowers the electrical resistivity of the polyaniline by two orders of magnitude for both the powder and the compact composites as demonstrated by their electrical resistance measurements conducted under loading. The lowest measured electrical resistivity values were 5 Ω·cm for 33% wt. graphene powder and 8 Ω·cm for 41% wt. graphene compacted composites. Cyclic electrical measurements under loading showed a distinct reproducible dependence of the bulk resistivity vs. applied pressure. This repetition is a key component for electro-mechanical sensors. To the authors’ best knowledge, this is the first report on polymerization of aniline in presence of graphene by the in-situ interfacial dynamic inverse emulsion polymerization technique and also the first report on cyclic electrical measurements under pressure of PANI/graphene nanocomposites.展开更多
Metallic nanoparticles and carbon nanomaterials have been extensively studied in enhanced oil recovery.Carbon nanotube(CNT)/TiO_(2) nanocomposite is synthesized and investigated in terms of contact angle,interfacial t...Metallic nanoparticles and carbon nanomaterials have been extensively studied in enhanced oil recovery.Carbon nanotube(CNT)/TiO_(2) nanocomposite is synthesized and investigated in terms of contact angle,interfacial tension(IFT),emulsion stability,etc.Its performance in oil displacement in porous media is evaluated through glass micromodel experiment.The synthesized CNT/TiO_(2) is composed of TiO_(2)-based nanocomposites and CNTs as reinforcement phase.TiO_(2) is the dominant crystalline phase,and TiO_(2) nanoparticles cover on the CNTs.CNT/TiO_(2) nanocomposite is able to alter the wetting conditions of the rock from strong oil-wet to hydrophilic conditions and effectively reduce the interfacial tension.CNT/TiO_(2) nanocomposite plays an effective role in stabilizing the Pickering emulsions,and even forms stable emulsions at high temperature as 90℃.For NaCl concentration of up to 2%,a stable emulsion can be formed even after 7 days.It is observed from glass micromodel experiments that the CNT/TiO_(2) nanofluid provides a higher recovery factor denoting its promising performance in enhanced oil recovery.展开更多
PMMA/reactive nanoclay nanocomposites were prepared by emulsion polymerization using two different reactive nanoclays. X-ray diffraction（XRD） and thermogravimetric analysis（TGA） results confirmed that the reactive...PMMA/reactive nanoclay nanocomposites were prepared by emulsion polymerization using two different reactive nanoclays. X-ray diffraction（XRD） and thermogravimetric analysis（TGA） results confirmed that the reactive nanoclays, kaolinite and montmorillonite, were obtained by the silylation reaction and the double bonds were grafted onto the edges and surfaces of the nanoclays. The presence of reactive nanoclays could increase the average molecular weights, the glass transition temperatures（Tg） and improve the thermal properties of nanocomposite. The tensile properties, Young＇s modulus, and the aging properties of the nanocomposite films were also enhanced while the light transmittance decreased. Furthermore, the nanocomposites with the reactive kaolinite presented better performances than that with the reactive montmorillonite. Finally, the action mechanism of the reactive nanoclays to the performances of PMMA/reactive nanoclay nanocomposites was proposed.展开更多
Aceclofenac is a new generational Non-Steroidal Anti-Inflammatory Drug (NSAID), and is considered a better alternative to the popular pain-killer diclofenac, as it overcomes some of the adverse gastrointestinal and ca...Aceclofenac is a new generational Non-Steroidal Anti-Inflammatory Drug (NSAID), and is considered a better alternative to the popular pain-killer diclofenac, as it overcomes some of the adverse gastrointestinal and cardiac side effects associated with the latter. However, the bioavailability of the drug remains limited due to low aqueous solubility (0.058 μg/mL) and poor dissolution characteristics. Hence, improving its dissolution characteristics is of prime significance in order to establish its optimal therapeutic efficacy. In an effort to tackle this issue, we report the use of novel Soluplus®-based nanocomposites, prepared from emulsion templates, as effective drug loading agent for aceclofenac. Nanoemulsion templates were prepared by high-shear homogenization using a probe sonicator. The emulsions were subsequently lyophilized to obtain free flowing powders. The amorphization of the drug with increasing polymer content was clearly observed from powder X-ray diffractogram, while the drug-polymer interaction was explored by FTIR spectroscopy. The phase purity and homogeneity of the formulation was characterized using Differential Scanning Calorimetry. The dissolution profiles of the formulations were established by an USP paddle apparatus. Phase solubility study was conducted to evaluate the effect of polymer concentration on aqueous solubility of aceclofenac. The values of Gibbs-free energy (ΔG°tr) associated with the aqueous solubility of aceclofenac in the presence of Soluplus was used to optimize the polymer content. The in vitro dissolution rates of aceclofenac from the nanoparticles were significantly higher compared to the pure drug. Thus, Soluplus nanoparticles provide promising formulations for the improvement of the dissolution profiles and thus, the bioavailability, of aceclofenac.展开更多
A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound (OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particle size an...A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound (OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particle size analyzer, transmission electron microscope (TEM), optical contact angle measurement (OCA) and dynamic mechanical analyzer (DMA). It was found that the protective agent, sodium polyacrylate (PA),could obviously improve the polymerization stability and the functional monomer, glycidyl methacrylate (GMA), could enhance the store stability of the latex. The particle size of poly(St-co-BA) latex decreased and then leveled off as OIHC content increased. TEM shows that the prepared polymers were actually organic-inorganic nanocomposites, and these films have better waterproof property than those prepared by traditional poly(St-co-BA) latex or organic silicone modified poly(St-co-BA) latex. The nanocomposite polymer has much higher glass transition temperature than organic silicone modified poly(St-co-BA) polymer containing the same organic silicone content.展开更多
基金This research was financially supported by the Key Project of China Educational Ministry (No. 103064)the Doctoral Foundation of University (No. 20020246031)
文摘Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.
文摘This paper describes a study on electrical resistivity under loading of polyaniline (PANI)/graphene nanocomposite powders and compacts. The composites were prepared by an in-situ interfacial dynamic inverse emulsion polymerization technique under sonication of aniline in the presence of graphene sheets in chloroform. During polymerization the graphene nanoplatelets are coated with PANI and are well dispersed both in the polymeric suspension and then in the dried polymer matrix as evidenced by cryogenic transmission electron microscopy (Cryo-TEM) and high resolution scanning microscopy (HRSEM). The presence of graphene nanoplatelets lowers the electrical resistivity of the polyaniline by two orders of magnitude for both the powder and the compact composites as demonstrated by their electrical resistance measurements conducted under loading. The lowest measured electrical resistivity values were 5 Ω·cm for 33% wt. graphene powder and 8 Ω·cm for 41% wt. graphene compacted composites. Cyclic electrical measurements under loading showed a distinct reproducible dependence of the bulk resistivity vs. applied pressure. This repetition is a key component for electro-mechanical sensors. To the authors’ best knowledge, this is the first report on polymerization of aniline in presence of graphene by the in-situ interfacial dynamic inverse emulsion polymerization technique and also the first report on cyclic electrical measurements under pressure of PANI/graphene nanocomposites.
文摘Metallic nanoparticles and carbon nanomaterials have been extensively studied in enhanced oil recovery.Carbon nanotube(CNT)/TiO_(2) nanocomposite is synthesized and investigated in terms of contact angle,interfacial tension(IFT),emulsion stability,etc.Its performance in oil displacement in porous media is evaluated through glass micromodel experiment.The synthesized CNT/TiO_(2) is composed of TiO_(2)-based nanocomposites and CNTs as reinforcement phase.TiO_(2) is the dominant crystalline phase,and TiO_(2) nanoparticles cover on the CNTs.CNT/TiO_(2) nanocomposite is able to alter the wetting conditions of the rock from strong oil-wet to hydrophilic conditions and effectively reduce the interfacial tension.CNT/TiO_(2) nanocomposite plays an effective role in stabilizing the Pickering emulsions,and even forms stable emulsions at high temperature as 90℃.For NaCl concentration of up to 2%,a stable emulsion can be formed even after 7 days.It is observed from glass micromodel experiments that the CNT/TiO_(2) nanofluid provides a higher recovery factor denoting its promising performance in enhanced oil recovery.
基金Funded by the National Youth Natural Science Foundation of China(No.21406247)
文摘PMMA/reactive nanoclay nanocomposites were prepared by emulsion polymerization using two different reactive nanoclays. X-ray diffraction（XRD） and thermogravimetric analysis（TGA） results confirmed that the reactive nanoclays, kaolinite and montmorillonite, were obtained by the silylation reaction and the double bonds were grafted onto the edges and surfaces of the nanoclays. The presence of reactive nanoclays could increase the average molecular weights, the glass transition temperatures（Tg） and improve the thermal properties of nanocomposite. The tensile properties, Young＇s modulus, and the aging properties of the nanocomposite films were also enhanced while the light transmittance decreased. Furthermore, the nanocomposites with the reactive kaolinite presented better performances than that with the reactive montmorillonite. Finally, the action mechanism of the reactive nanoclays to the performances of PMMA/reactive nanoclay nanocomposites was proposed.
文摘Aceclofenac is a new generational Non-Steroidal Anti-Inflammatory Drug (NSAID), and is considered a better alternative to the popular pain-killer diclofenac, as it overcomes some of the adverse gastrointestinal and cardiac side effects associated with the latter. However, the bioavailability of the drug remains limited due to low aqueous solubility (0.058 μg/mL) and poor dissolution characteristics. Hence, improving its dissolution characteristics is of prime significance in order to establish its optimal therapeutic efficacy. In an effort to tackle this issue, we report the use of novel Soluplus®-based nanocomposites, prepared from emulsion templates, as effective drug loading agent for aceclofenac. Nanoemulsion templates were prepared by high-shear homogenization using a probe sonicator. The emulsions were subsequently lyophilized to obtain free flowing powders. The amorphization of the drug with increasing polymer content was clearly observed from powder X-ray diffractogram, while the drug-polymer interaction was explored by FTIR spectroscopy. The phase purity and homogeneity of the formulation was characterized using Differential Scanning Calorimetry. The dissolution profiles of the formulations were established by an USP paddle apparatus. Phase solubility study was conducted to evaluate the effect of polymer concentration on aqueous solubility of aceclofenac. The values of Gibbs-free energy (ΔG°tr) associated with the aqueous solubility of aceclofenac in the presence of Soluplus was used to optimize the polymer content. The in vitro dissolution rates of aceclofenac from the nanoparticles were significantly higher compared to the pure drug. Thus, Soluplus nanoparticles provide promising formulations for the improvement of the dissolution profiles and thus, the bioavailability, of aceclofenac.
基金Supported by the National "863" Project (No. 2001 AA 320206)and Shanghai Nano Special Foundation(No. 0120nm034).
文摘A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound (OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particle size analyzer, transmission electron microscope (TEM), optical contact angle measurement (OCA) and dynamic mechanical analyzer (DMA). It was found that the protective agent, sodium polyacrylate (PA),could obviously improve the polymerization stability and the functional monomer, glycidyl methacrylate (GMA), could enhance the store stability of the latex. The particle size of poly(St-co-BA) latex decreased and then leveled off as OIHC content increased. TEM shows that the prepared polymers were actually organic-inorganic nanocomposites, and these films have better waterproof property than those prepared by traditional poly(St-co-BA) latex or organic silicone modified poly(St-co-BA) latex. The nanocomposite polymer has much higher glass transition temperature than organic silicone modified poly(St-co-BA) polymer containing the same organic silicone content.
