Preparation and properties of nitrogen-containing hollow carbon nanospheres by pyrolysis of polyaniline-lignosulfonate composites

Polyaniline-lignosulfonate composite hollow spheres were synthesized by using one-step unstirred polymerization of aniline in the presence of lignosulfonate. Novel nitrogen-containing hollow carbon nanospheres were prepared by direct pyrolysis of the polyaniline-lignosulfonate composite spheres at different temperatures under a nitrogen atmosphere. Thermal behavior of the polyaniline-lignosulfonate composite spheres was studied by TG-DTG, FTIR and element analyze instruments. The resultant carbon spheres were characterized by SEM, XRD and nitrogen adsorption-desorption measurement. It was found that the pyrolysis products of the polyaniline-lignosulfonate composite spheres were made up of uniform hollow carbon nanospheres with an average diameter of 135 nm. Furthermore, the hollow carbon nanospheres exhibit high BET surface area range from 381.6 m² g⁻¹ to 700.2 m² g⁻¹. The hollow carbon nanospheres could be used as adsorbents of papain. The papain adsorption capacity for the carbon spheres prepared at 1200 °C was up to 1161 mg g⁻¹ at an initial papain concentration of 10 mg mL⁻¹ at 25 °C.     

Coating of multiwalled carbon nanotubes with polymer nanospheres through microemulsion polymerization

We report a simple and noncovalent method for coating multiwalled carbon nanotubes (MWCNTs) with polyaniline (PANI) nanospheres using a microemulsion polymerization method. In this method, aniline polymerization is performed with MWCNTs in the presence of sodium dodecyl sulfate (SDS), which serves as both a surfactant and a dopant. Morphological, structural, thermal, and electrical properties of MWCNT–PANI nanocomposites were analyzed. The TEM results of the nanocomposites prepared with surfactant reveal that 30–50-nm-diameter PANI nanospheres were coated on the surface of the MWCNTs. Composites prepared without surfactant were found to be in core–sheath-type cable structures. The conductivities of the nanocomposites synthesized through microemulsion polymerization were found to be one order of magnitude higher than both the conductivities of pure PANI and the composites prepared via in situ chemical polymerization without an assisting SDS surfactant. The mechanism for the formation of nanostructured composites is presented.     

Preparation and morphology of SiO2/PMMA nanohybrids by microemulsion polymerization

Polymethylmethacrylate/SiO2 nanocomposite particles were prepared through microemulsion polymerization by using the silica particles coated with 3-(trimethoxysilyl) propyl methacrylate (MSMA) in both acidic and alkaline conditions. Core-shell and other interesting morphology nanocomposite particles were obtained depending on the pH of the microemulsion, the amount of silanol, and the coupling agent concentration employed. Then, by combining a modified microemulsion polymerization process, i.e., an additional monomer-adding process, the solid contents of the polymer/inorganic nanocomposite microemulsion could greatly increase. Thus, by adjusting these parameters and polymerization process, it was possible to control the morphology and size of the nanocomposites.     

Palladium-catalyzed Suzuki cross-coupling reactions in a microemulsion

An enhancement of palladium-catalyzed Suzuki cross-coupling reactions between substrates possessing long-chain alkyl or oxyalkyl substituents in two-phase media, in the presence of sodium dodecylsulfate, is shown. Quantitative evaluations of the influence of SDS on the reaction rates were determined.     

Ultrasonically induced microemulsion polymerization of styrene

In this paper, ultrasonically induced microemulsion polymerization of styrene was successfully performed, possessing many merits such as high polymerization rate, the formation of small latex particles with a narrow size distribution, the absence of initiator and relatively low surfactant concentration. The monomer conversion reached 70% in 1 h, and the average diameter of polystyrene (PS) latex was about 30 nm which could be prepared with 3% surfactant (sodium dodecyl sulfate, SDS) concentration. The molecular weight of PS was around 10⁶ and the poly-distribution index was 1.06, indicating a very narrow distribution. Several influencing factors were investigated in detail, showing that ultrasonically induced microemulsion polymerization is a new route to prepare PS nanoparticles.     

Kinetics of ring-opening polymerization of octamethylcyclotetrasiloxane in microemulsion

Polysiloxane latexes were prepared by microemulsion polymerization of octamethylcyclotetrasiloxane(D4) in the absence of co-emulsifier with octadecyl trimethyl ammonium chloride as a cationic emulsiner and potassium hydrate as an initiator.The particle size was determined by the dynamic light scattering(DLS) technique and the reaction rates of the polymerization were discussed.Furthermore,the kinetics was studied by an initial-rate method,and the effects of the monomer,emulsiner and initiator concentrations and the temperature on polymerization conversions were investigated.From the kinetic results,the rate of polymerization,R_p at 80 ℃ can be expressed as R_p = k[D4]~(0.79)[OTAC]~(0.64)[KOH]~(0.38) and the apparent activation energy(E_a),which was determined by half-period method,is 95.32 kJ mol~(-1).     

复合乳化剂微乳液法制备聚苯胺及其电化学性能

采用复合乳化剂微乳液法合成了导电聚苯胺(PANI),以碳纸负载PANI为工作电极,考察了十二烷基苯磺酸钠(SDBS)和聚乙二醇辛基苯基醚(TX-100)的配比及其复合乳化剂(E)和氧化剂(APS)用量对复合乳化剂微乳液法合成PANI电化学性能(循环伏安、塔费尔)的影响;通过对产物电导率和产率的对比分析,印证了PANI电化学性能表征结果的有效性。结果表明：当SDBS与TX-100的质量比为1/2,E与苯胺(An)单体的质量比为5/3,APS与An的摩尔比为1.2时,PANI的各项性能指标达到最好,且产物的循环伏安峰电流、腐蚀电位和电导率均高于单组分乳化剂SDBS或TX-100微乳液法制备的PANI。     

Polymer–silica hybrids obtained by microemulsion polymerization

The styrene (St), butyl acrylate (BuA), and methyl methacrylate (MMA) polymerization in microemulsion in the presence of sodium dodecylsulfate is studied. This process is conducted in the presence of some comonomers having groups that can participate in sol–gel processes: 3(trimethyloxysilyl) propyl methacrylate (MPTS), triethoxy vinylsilane (VTES), and a comonomer with a sulfate group, styrene sodium sulfonate (StSO₃Na). It has been observed that stabile latexes are obtained by radical polymerization at pH = 7, followed by a sol–gel process in the presence of ammonia. Latex particles sizes and zeta potential grow with MTPS concentration and in StSO₃Na presence. VTES effect depends on its reactivity in St, MMA, and BuA copolymerization. Glass transition temperature and thermal decomposing temperature are influences by functional comonomer concentration and chemical structure. The Fourier transform infrared spectrum and inorganic residue growth after organic part thermal decomposition shows the presence of silica in obtained latexes.     

Synthesis of Ag-SiO2 composite nanospheres and their catalytic activity

A simple,mild,and time-saving method is employed to synthesize Ag-SiO2 composite nanospheres with Ag nanoparticles uniformly distributed on the surface of SiO2 nanoparticles.The chemical elements and the morphology of Ag-SiO2 composite nanospheres were analyzed with transmission electron microscopy(TEM),X-ray power diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).On the surface of Ag-SiO2 composite nanospheres,silane coupling agent(KH-550)is introduced as an intermediary to connect the surfaces of SiO2 nanospheres and Ag nanoparticles,which is also helpful for avoiding the aggregation of Ag nanoparticles.It is found that Ag-SiO2 composite nanospheres have very good catalytic properties for the reduction of organic dyes,which may have potential application in wastewater treatment.     

Formulation optimization and in situ absorption in rat intestinal tract of quercetin-loaded microemulsion

A new microemulsion system has been developed to increase the solubility and oral absorption of quercetin, a poorly water-soluble drug. The formulation of quercetin-loaded microemulsion was optimized by a simplex lattice experiment design. The optimized microemulsion formulation consisted of oil (7%, w/w), surfactant (48%, w/w), and cosurfactant (45%, w/w). Under this condition, the mean droplet diameter of microemulsion was 38.9 nm and solubility of quercetin in the microemulsion was 4.138 mg/ml. The in situ absorption property of quercetin-loaded microemulsion in rat intestine was studied and the results showed there was significant difference in absorption parameters such as K_a, t_1/2 and uptake percentages between microemulsion and micelle solution containing quercetin. The study on absorption percentage in different regions of rat intestine attested that the colon had the best permeability, followed by ileum, duodenum in order. It can be concluded that microemulsion can improve the solubility and oral absorption of quercetin, a poorly water-soluble drug.     

In situ polymerization of aniline in electrospun microfbers简

Conductive microfibers with an average diameter of ca. 1.0 mm were prepared by in situ polymerization of aniline, in which poly(vinylchloride-acrylonitrile)(PVC-AN) was used as the filament-material in electrospinning to form precursor microfibers and carry the aniline monomers. Fourier-transform infrared(FTIR) results demonstrated that PANi was successfully polymerized in the microfibers. The morphology of the PVC-AN-PANi microfibers was observed by scanning electron microscopy(SEM). Results of differential scanning calorimetry indicated that the polymer composite of PVC-AN-PANi formed via molecular interactions. Although the conductivity of PVC-AN-PANi microfibers was still limited(2.2 fi 10à8S/cm), this method provided an effective and convenient approach for preparing highly uniform and soft microfibrous electrodes.     

Radiation-induced polymerization of methyl methacrylate in microemulsion with high monomer content

γ-Ray-induced polymerization of methyl methacrylate was conducted in a microemulsion stabilized by a mixture of sodium of 12-acryloxy-9-octadecenoic acid (AOA) and sodium dodecyl sulfate (SDS) with various weight ratios at room temperature. The experimental data showed that the mixture of AOA and SDS with a weight ratio 2 was an efficient surfactant system for the microemulsion containing 38.6 wt% MMA and 5.5 wt% surfactant. The effects of MMA concentration and dose rate on the polymerization kinetics and particle size are discussed.     

ZnO纳米球的制备及性能研究进展

纳米ZnO以其独特的结构和性能,在建材、陶瓷、化妆品及电子领域具有广泛的应用。球形纳米ZnO与其他结构的纳米ZnO相比,具有结构的高度对称性、比表面积大、独特的光性能等优点,使其具有更广阔的应用前景。本文介绍了纯纳米ZnO球、掺杂及复合的纳米ZnO球等ZnO纳米球种类并综述了纳米ZnO球的主要制备方法及相关性能。     

Miniemulsion polymerization of cyclodextrin nanospheres for water purification from organic pollutants

The pollution of groundwater and wells has become an environmental and economic hazard as a result of waste spillage, and industrial applications such as pesticides in agriculture. Conventional treatment techniques such as sand filtration, sedimentation, flocculation, coagulation, chlorination, and activated carbon are not very effective in reducing the concentration of the organic pollutants in the presence of dissolved organic matter. The objective of the current work is to design an efficient technology for water purification from organic contaminants by a new class of polymeric nanospheres based on cyclodextrins as building blocks. We synthesized a series of cross-linked cyclodextrin polymeric nanospheres of different sizes by a unique method, miniemulsion polymerization. These cyclodextrin nanospheres exhibit a high ability to absorb aromatic organic molecules such as toluene and phenol. Sorption experiments in solutions with high concentrations of corresponding organic molecules show a high adsorption capacity.     

Generalization of in-situ polymerization method for preparing core-shell polymeric nanospheres and hollow spheres

According to the new method of preparing core-shell nanospheres developed by our group, by using two monomers, 2-hydroxypropyl methacrylate(HPMA) and vinyl acetate(VAc), two kinds of core-shell nanospheres with poly(ɛ-caprolactone) (PCL) as the core and crosslinked poly(2-hydroxypropyl methacrylate) (PHPMA) or poly(vinyl acetate) (PVAc) as the shell were successfully prepared under similar conditions. After degrading the PCL cores of the two kinds of nanospheres by lipase, the corresponding crosslinked poly(methyl acrylic acid) hollow spheres and crosslinked poly(vinyl alcohol) hollow spheres were obtained. Results indicate that the new method we proposed for preparing core-shell polymeric nanospheres via in-situ polymerization can be generalized to a certain extent, and it is suitable for many systems provided the monomer used is soluble in water, while its corresponding polymer is insoluble in water. Translated from Chemical Journal of Chinese University, 2006, 27(9): 1762–1766 [译自: 高等学校化学学报]     

Polystyrene/graphene composite electrode fabricated by in situ polymerization for capillary electrophoretic determination of bioactive constituents in Herba Houttuyniae

A novel graphene/polystyrene composite electrode was developed for the enhanced amperometric detection of CE in this work. The composite electrode was fabricated on the basis of the in situ polymerization of a mixture of graphene and prepolymerized styrene in the bore of a piece of fused‐silica capillary under heat. SEM, XRD, and FTIR offered insights into the nature of the composite. The results indicated that graphenes were well dispersed and embedded throughout the PS matrix to form an interconnected conducting network. The performance of this unique graphene‐based detector has been demonstrated by separating and detecting rutin, isoquercitrin, quercitrin, and chlorogenic acid in Herba Houttuyniae (a traditional Chinese medicine) in combination with CE. The prepared graphene‐based CE detector offered significantly lower detection potential, yielded enhanced signal‐to‐noise characteristics, and exhibited high resistance to surface fouling and enhanced stability. It showed long‐term stability and reproducibility with a relative standard deviation of 3.1% for the peak current (n=15).     

5-氟尿嘧啶/壳聚糖载药纳米微球的制备及性能

以三聚磷酸钠为交联剂,采用离子交联法制备了5-氟尿嘧啶/壳聚糖纳米微球,评价其性能、体外释药性能及对人肺癌细胞GLC-82的体外杀伤效应,并通过Zeta电位和红外光谱分析载药纳米微球形成机理.结果表明,所制备的5-Fu/CS纳米微球平均包封率为32.3%,平均载药量为25.6%,平均粒径为253nm,平均zeta电势为+8.38mV,成球性及分散性良好.CS载药纳米微球具有缓释性能,体外释药行为符合双向动力学规律.在体外作用72h,CS载药纳米微球对人肺癌细胞GLC-82的杀伤率达66.6%,杀伤效果明显优于5-Fu对照组.     

Preparation of micro- and nanospheres with superamphiphobic surfaces by dispersion polymerization

Micro- and nanospheres with superamphiphobic surfaces were prepared by a simple method that employed the conventional dispersion polymerization of perfluoroalkyl methacrylates in methanol. The polymerizations of 2,2,2-trifluoroethyl methacrylate (TFMA) produced microspheres with an average 4.12-μm diameter, while that of 2-(perfluorooctyl)ethyl methacrylate (POMA) provided nanospheres with a 679-nm diameter. An X-ray photoelectron spectroscopy analysis revealed that the fluorine atoms were highly concentrated on the top of the sphere surfaces. It was found that the surface coated with the spheres had a superamphiphobicity. The water contact angles were 150° for the PTFMA microspheres and 173° for the PPOMA nanospheres, while the diiodomethane contact angles were 159° for the microspheres and 160° for the nanospheres. The synergistic effect of the spherical structure and the high concentration of fluorine on the top of the surface produced the superamphiphobicity.     

Preparation of hollow silica nanospheres in O/W microemulsion system by hydrothermal temperature changes

Hollow silica nanospheres with wrinkled or smooth surfaces were successfully fabricated through a hydrothermal method. In this method, oil-in-water microemulsion (composed of cyclohexane, water, ethanol, and cetyltrimethylammonium bromide), and polyvinylpyrrolidone were utilized as template and capping agent, respectively. In such a facile synthesis, we can well realize the morphological transformation of spheres with radially oriented mesochannels to hollow structures of silica nanoparticle only by regulating the hydrothermal temperature from 100 °C to 200 °C. Synthesized samples with different mesostructures were then used as supports to immobilize Candida rugosa lipase (CRL). The immobilized CRL was employed as a new biocatalyst for biodiesel production through the esterification of heptanoic acid with ethanol. The conversion ratio of heptanoic acid with ethanol catalyzed by the immobilized CRL was also evaluated. Results of this study suggest that the prepared samples have potential applications in biocatalysis.