New Approach to Enhance the Yield Stress of Electro‐Rheological Fluids by Polyaniline‐Coated Layered Silicate Nanocomposites

We synthesized new polyaniline (PANI)/organoclay (aminosilane surface‐treated) nanocomposite particles and prepared electro‐rheological (ER) fluids by dispersing the particles in silicone oil. A distinct enhancement in yield stress was observed due to the presence of PANI‐coated clay particles. The effects of delaminated clay on the ER yield stress were investigated and compared with other ER fluid systems, which use PANI particles only or a simply intercalated PANI/clay nanocomposite.     

Electrorheological characteristics of polyaniline/titanate composite nanotube suspensions

In this paper, one-dimensional polyaniline/titanate (PANI/TN) composite nanotubes were synthesized by in situ chemical oxidative polymerization directed by block copolymer. These novel nanocomposite particles were used as a dispersed phase in electrorheological (ER) fluids, and the ER properties were investigated under both steady and dynamic shear. It was found that the ER activity of PANI/TN fluids varied with the ratio of aniline to titanate, and the PANI/TN suspensions showed a higher ER effect than that made by sphere-like PANI/TiO₂ nanoparticles. These observations were well interpreted by their dielectric spectra analysis; a larger dielectric loss enhancement and a faster rate of interfacial polarization were responsible for a higher ER activity of nanotubular PANI/TN-based fluids.     

Iron oxide/MCM-41 mesoporous nanocomposites and their magnetorheology

Mesoporous nanocomposite materials of magnetic iron oxide-containing MCM-41 (IO/MCM-41) were prepared by simple thermal oxidation of Fe-containing MCM-41 initially prepared by a direct synthesis route using Fe³⁺ salt. The magnetic saturation of the fabricated nanocomposite materials was measured using a vibrating sample magnetometer, while surface morphology and inner framework of the composite materials were studied using a field emission scanning electron microscope and a transmission electron microscope to confirm their mesoporous nanocomposite formation. The fabricated magnetic materials were then adopted as a magnetorheological (MR) fluid, where the IO/MCM-41 magnetic nanocomposites were dispersed in a nonmagnetic medium oil in addition to as an additive for carbonyl iron-based MR fluid. Their MR properties of flow curve along with yield stress and viscoelastic properties under applied magnetic fields were investigated using a rotational rheometer.     

Electrorheological behavior of copper phthalocyanine-doped MCM-41 suspensions

A type of anhydrous electrorheological (ER) material of copper phthalocyanine (CuPC)-doped MCM-41 was synthesized by in situ micelle-assisted incorporation of CuPC during MCM-41 synthesis. The ER behavior of the suspensions of CuPC-doped MCM-41 particles in paraffin liquid with a 30 wt.% was investigated under an applied electric field. It is found that the ER effect increased with increasing the CuPC-doping ratio. The dopants of CuPC molecules within the mesochannel of MCM-41 mesoporous sieve improved the conductivity of the particles, and produced a proper conductivity of 10⁻⁷ S m⁻¹. Dielectric spectra of the fluids were also measured to examine their possible correlation with the ER behavior, and the results were explained based on Ikazaki's criterion that the relaxation frequency must be in the range 100–10⁵ Hz and the difference in the dielectric constant must be large below and above the relaxation frequency for an appreciable ER effect.     

Preparation, characterization and optical properties of lanthanum-(nanometer MCM-41) composite material

Nanometer MCM-41 molecular sieve was prepared under a base condition by using cetyltrimethylammonium bromide as template and tetraethyl orthosilicate as silica source by means of hydrothermal method. Lanthanum(III) was incorporated into the nanometer MCM-41 by a liquid phase grafting method. The prepared nanocomposite materials were characterized by means of powder X-ray diffraction, spectrophotometric anaylsis, Fourier transform infrared spectroscopy, low temperature nitrogen adsorption-desorption technique, solid diffuse reflectance absorption spectra and luminescence. The powder X-ray diffraction studies show that the nanometer MCM-41 molecular sieve is successfully prepared. The highly ordered mesoporous two-dimensional hexagonal channel structure and framework of the support MCM-41 is retained intact in the prepared composite material La-(nanometer MCM-41). The spectrophotometric anaylsis indicates that lanthanum exists in the prepared nanocomposite materials. The Fourier transform infrared spectra indicate that the framework of the MCM-41 molecular sieve still remains in the prepared nanocomposite materials and some framework vibration peaks show blue shifts relative to those of the MCM-41 molecular sieve. The low temperature nitrogen adsorption-desorption indicates that the guest locates in the channel of the molecular sieve. Compared with bulk lanthanum oxide, the guest in the channel of the molecular sieve has smaller particle size and shows a significant blue shift of optical absorption band in solid diffuse reflectance absorption spectra. The observed blue shift in the solid state diffuse reflectance absorption spectra of the lanthanum-(nanometer MCM-41) sample show the obvious stereoscopic confinement effect of the channel of the host on the guest, which further indicates the successful encapsulation of the guest in the host. The La-(nanometer MCM-41) sample shows luminescence.     

纳米MCM-41组装DBC-偶氮胂的研究

以纳米MCM-41孔道为模版,组装制备了二溴对氯偶氮胂(DBC-ASA)纳米簇合物。采用化学分析、粉末X-射线衍射、77 K N2吸附-解吸附、红外光谱、固体扩散漫反射光谱及发光光谱表征了制备的(MCM-41)-(DBC-ASA)主-客体纳米复合材料。结果表明,DBC-ASA成功地组装在了主体MCM-41中,并且处于主体分子筛材料的纳米孔道中。(MCM-41)-(DBC-ASA)纳米复合材料具有作为发光材料的应用前景。     

Preparation, characterization, and photocatalytic activity of polyaniline/ZnO nanocomposite

Polyaniline (PANI)/zinc oxide (ZnO) nanocomposite was synthesized by in-situ polymerization. X-ray diffraction patterns, UV?Cvisible spectroscopy, SEM, and TEM were used to characterize the composition and structure of the nanocomposite. Nanostructured PANI/ZnO composite was used as photocatalyst in the photodegradation of methylene blue dye molecules in aqueous solution. The photocatalytic activity of PANI/ZnO nanocomposite under UV and visible light irradiation was evaluated and was compared with that of ZnO nanoparticles. ZnO/PANI core?Cshell nanocomposite had greater photocatalytic activity than ZnO nanoparticles and pristine PANI under visible light irradiation. According to these results, application of PANI as a shell on the surface of ZnO nanoparticles causes the enhanced photocatalytic activity of the PANI/ZnO nanocomposite. Also UV?Cvisible spectroscopy studies showed that the absorption peak for PANI/ZnO nanocomposite has a red shift toward visible wavelengths compared with the ZnO nanoparticles and pristine PANI. The effect of different operating conditions on the photocatalytic performance of PANI/ZnO nanocomposite in the photodegradation of methylene blue dye molecules was investigated in a bath experimental setup.     

(MCM-41)-La_2O_3纳米复合材料的制备、表征及光学性质

借助水热法,以正硅酸乙酯为硅源,十六烷基三甲基溴化铵为模板剂,在碱性条件下制备了纳米MCM-41分子筛。通过固相热扩散法将La2O3组装到MCM-41介孔孔道中,制备出含La2O3不同浓度的(MCM-41)-La2O3主-客体纳米复合材料。采用化学分析、粉末XRD、FTIR、77K低温N2吸附-解吸附、固体扩散漫反射吸收光谱、拉曼光谱、扫描电镜和发光光谱对主-客体复合材料进行表征。粉末XRD结果表明,La2O3组装到MCM-41分子筛的孔道后并未破坏分子筛骨架,在所制备的(MCM-41)-La2O3主-客体纳米复合材料中MCM-41骨架结构仍然具有较高的有序性,并且,随着植入客体材料浓度的增加复合材料的有序度有所降低。红外光谱表明所制备的纳米复合材料主体分子筛骨架完好;低温氮气吸附-解吸附技术表明La2O3已经部分地占据了MCM-41分子筛孔道,导致分子筛的比表面积和孔体积都有所降低;固体扩散漫反射吸收光谱表明吸收光谱的吸收峰发生了蓝移现象,并表现出量子限域效应,说明La2O3已经组装到了MCM-41分子筛的孔道中;拉曼光谱表明所制备的复合材料没有出现新的特征峰,表明La2O3已经组装到了MCM-41分子筛的孔道中;扫描电镜表明(MCM-41)-La2O3样品的外观非常规整,主要呈现的是球状结构,La2O3含量为10%时,(MCM-41)-La2O3的平均粒径为(114±10)nm。发光光谱研究结果表明,所制备的复合材料(MCM-41)-La2O3样品在396nm处具有较好的发光性质,因而具有作为发光材料潜在应用前景。     

Improved electrorheological effect in polyaniline nanocomposite suspensions

We prepared polyaniline (PANI)/clay composites that are composed of both PANI-clay nanocomposite particles and pure PANI particles. The PANI-clay nanocomposite particles were made during the polymerization process, wherein PANI particles are attached on the surface of exfoliated clay particles modified by an aminosilane group. The PANI/clay composites were used as electrorheological fluids (ERFs) by dispersing them in silicon oil. The PANI-clay nanocomposite particles, which can form columnar structure under an electric field, strongly enhance the mechanical rigidity of the suspensions. The maximum yield stress of the PANI/clay composite suspensions (15 wt% in silicon oil) was 1.6 kPa at 3 kV/mm, while that of pure PANI was 300 Pa at the same electric field. A mechanism to explain the yield behaviors of the PANI-based nanocomposite suspensions is proposed.     

Doping polyaniline with pristine carbon nanotubes into electroactive nanocomposite in neutral and alkaline media

This study describes a facile but effective route to synthesis of electroactive polyaniline (PANI) in the neutral and alkaline media simply with pristine single-walled carbon nanotubes (SWNTs) as the dopant. Cyclic voltammetry (CV) studies reveal that the SWNT/PANI nanocomposite processes a good electrochemical activity in the neutral and alkaline media. Control experiments with PANI mixed with heat-treated SWNTs imply that the electrochemical properties of the SWNT/PANI nanocomposite in the neutral and alkaline media do not result from the presence of carboxylic groups at SWNTs themselves, and in turn show that the pristine SWNTs can be potentially used as a new and effective dopant to preserve the electrochemical property of PANI in the neutral and alkaline media. This property of the SWNT/PANI nanocomposite is reasonably envisaged to be promising for electrochemical investigations and electroanalytical applications, especially for the development of electrochemical sensors, biosensors and biofuel cells.     

Structural and electrochemical characterization of polyaniline/LiCoO2 nanocomposites prepared via a Pickering emulsion

Polyaniline (PANI)/LiCoO₂ nanocomposite materials are successfully ready through a solid-stabilized emulsion (Pickering emulsion) route. The properties of nanocomposite materials have been put to the test because of their possible relevance to electrodes of lithium batteries. Such nanocomposite materials appear thanks to the polymerization of aniline in Pickering emulsion stabilized with LiCoO₂ particles. PANI has been produced through oxidative polymerization of aniline and ammonium persulfate in HCl solution. The nanocomposite materials of PANI/LiCoO₂ could be formed with low amounts of PANI. The morphology of PANI/LiCoO₂ nanocomposite materials shows nanofibers and round-shape-like morphology. It was found that the morphology of the resulting nanocomposites depended on the amount of LiCoO₂ used in the reaction system. Ammonium persulfate caused the loss of lithium from LiCoO₂ when it was used at high concentration in the polymerization recipe. Highly resolved splitting of 006/102 and 108/110 peaks in the XRD pattern provide evidence to well-ordered layered structure of the PANI/LiCoO₂ nanocomposite materials with high LiCoO₂ content. The ratios of the intensities of 003 and 104 peaks were found to be higher than 1.2 indicating no pronounced mixing of the lithium and cobalt cations. The electrochemical reactivity of PANI/LiCoO₂ nanocomposites as positive electrode in a lithium battery was examined during lithium ion deinsertion and insertion by galvanostatic charge–discharge testing; PANI/LiCoO₂ nanocomposite materials exhibited better electrochemical performance by increasing the reaction reversibility and capacity compared to that of the pristine LiCoO₂ cathode. The best advancement has been observed for the PANI/LiCoO₂ nanocomposite 5 wt.% of aniline.     

Towards site-specific nanoparticles for drug delivery application: preparation,characterization and release performance

Due to the uncontrollable drug release, traditional chemotherapies could cause great side-effects and are detrimental to normal tissue or organs. Therefore, to avoid those side-effects, drug delivery system (DDS) which is capable of releasing drug molecules at target area with controllable rate according to the development of the disease or to certain functions of the organism/biological rhythm, has attracted especially focus in recent years. In this research, we devoted our efforts in constructing a core–shell nanocomposite to meet the above requirements. The superparamagnetic Fe₃O₄ nanoparticles were chosen as the core to introduce the magnetic guiding as well as site-specific properties in this novel drug carrier. The core was further encapsulated by silica-based molecular sieve MCM-41 (briefly denoted as MS in this research), which was consisted by immense highly ordered hexagonal tunnels to offer plenty cavity for molecules of drug. A light stimuli-responsive ligand, which is a derivative from light-responsive precursor 4,5-diazafluoren-9-one (indicated in the paper as DAFO), was further connected to the MCM-41 tunnels. The ligand can be excited by light and will flip over, making the tunnels of MCM-41 switch from close to open with light on and light off. The nanocomposite thus became capable of releasing drug molecules at certain wavelength of light. In the final, the nanoparticles were tested via SEM/TEM, XRD, FT-IR spectra, thermogravimetry and N₂ adsorption/desorption to verify the structure. The MTT testing of our nanocomposite reveals no obvious cytotoxicity with non-morbid L929 murine fibroblast cells line, indicating that it could be used as a DDS candidate. The cargo releasing behaviors were studied on cytarabine loaded composite: DAFO@MS@Fe₃O₄ in simulated body fluids.     

Adsorption of acid blue on synthesized polymeric nanocomposites,PPy/MCM-41 and PAni/MCM-41: Isotherm,thermodynamic and kinetic studies

In the this research, removal of acid blue 62 from aqueous solution using mesoporous crystalline material-41 (MCM-41) loaded by polypyrrole (PPy) and polyaniline (PAni) was investigated. Synthesized composites were characterized by SEM, TEM, FTIR, XRD and BET analysis. Langmuir adsorption isotherm showed the best compatibility with the experimental data in comparison with other isotherm models (q_m = 55.55 mg/L). Kinetic studies proved that the adsorption process is compatible with the pseudo-second-order kinetic model. Thermodynamic parameters such as Gibbs free energy changes (ΔG^o), Enthalpy changes (ΔH^o) and Entropy changes (ΔS^o) were calculated. Negative value of ΔG^o and positive value of ΔH^o show that adsorption of Acid blue 62 on PPy/MCM-41 nanocomposite is a spontaneous process also endothermic.     

无溶剂高度分散Ni/MCM-41催化剂的制备及其萘加氢性能

分别用机械研磨无溶剂法、添加柠檬酸无溶剂法制备了 Ni/MCM-41催化剂,对所制催化剂进行了分析表征,探究其萘加氢反应性能并与常规浸渍法进行了对比.与常规浸渍法相比,机械研磨无溶剂法所制催化剂的物理性质相近,金属镍分散度和萘加氢性能略有提高;添加柠檬酸无溶剂法则显著提升了催化剂的分散度和萘加氢性能,金属镍分散度由6....     

Electrochemical preparation of distinct polyaniline nanostructures by surface charge control of polystyrene nanoparticle templates

A family of nanostructured polyaniline (PANI) materials including polystyrene (PS)/PANI core/shell particles, PANI hollow spheres, PANI/PS nanocomposite and nanoporous PANI, were conveniently prepared by surface charge control of PS nanoparticle templates which resulted in different polymer growth mechanisms when PANI was electropolymerized around the templates.     

杂原子介孔Co-MCM-41分子筛的制备及其吸附脱氮性能

采用水热法合成了介孔MCM-41和Co-MCM-41分子筛,并利用XRD、FT-IR、低温N₂吸附-脱附和NH₃-TPD等方法对合成的分子筛进行了表征。考察了晶化时间、晶化温度、陈化时间对合成介孔Co-MCM-41分子筛的影响,确定较适宜的合成条件为陈化时间1 h,晶化温度110 ℃,晶化时间2 d。XRD 和FT-IR表征结果说明,Co原子已经进入MCM-41的骨架。MCM-41和Co-MCM-41的平均孔径均为2.82 nm,BET比表面积分别为986.42和 637.69 m²/g,孔容分别为0.762 1和0.537 2 m³/g。NH₃-TPD的表征结果表明,MCM-41和Co-MCM-41的酸性都较弱,但Co-MCM-41的酸性明显强于MCM-41。在此基础上,利用合成的MCM-41和Co-MCM-41吸附脱除氮含量为1 737.35 μg/g的模拟燃料中的喹啉。喹啉分子尺寸的模拟结果为0.711 6 nm × 0.500 2 nm,说明其可以很容易地进入MCM-41和Co-MCM-41的介孔孔道中。Co-MCM-41分子筛的氮脱除率明显高于MCM-41,这是由于其较强的酸性及与喹啉之间的化学吸附,而且,Co-MCM-41吸附脱氮具有较好的再生性能。     

PtSn/Al2O3/MCM-41催化剂的丙烷脱氢催化性能

用微型催化反应装置评价, 并结合X射线粉末衍射(XRD)、表面积和孔结构测试、程序升温还原(TPR)、氢化学吸附和热重分析等方法研究了负载型PtSn/γ-Al2O3, PtSn/MCM-41和PtSn/Al2O3/MCM-41催化剂的丙烷脱氢反应催化性能. 发现PtSn/Al2O3/MCM-41催化剂具有较PtSn/MCM-41催化剂高的丙烷脱氢反应活性和较PtSn/γ-Al2O3催化剂高的反应稳定性. 实验结果表明, 纯硅MCM-41载体表面的锡物种因与载体相互作用较弱故易被还原, 导致铂金属分散度和催化剂的丙烷脱氢活性较低. 用Al2O3修饰MCM-41可以增强Sn物种与Al2O3/MCM-41载体之间的相互作用, 提高PtSn/Al2O3/MCM-41催化剂铂金属分散度和丙烷脱氢催化活性. 并且, 积炭后的PtSn/Al2O3/MCM-41催化剂具有较高的铂金属表面裸露度, 故具有较高的丙烷脱氢反应稳定性. PtSn/Al2O3/MCM-41催化剂优良的丙烷脱氢催化性能可能不仅与Sn-载体Al2O3/MCM-41较强的相互作用有关, 而且与Al2O3/MCM-41载体的介孔结构有关.     

Polyaniline microsphere encapsulated by poly(methyl methacrylate) and investigation of its electrorheological properties

Microspheres consisting of a poly(methyl methacrylate) (PMMA) shell wrapping the conductive polyaniline (PANI) particle as a core were prepared by an in-situ suspension polymerization method and then adopted as an electrorheological (ER) material. The polymerization reaction and encapsulation were confirmed by Fourier transform infrared spectrum analysis. The rod-like PANI particles were synthesized via an emulsion polymerization protocol and observed by transmission electron microscopy. In addition, a spherical shape of encapsulated PANI/PMMA (core/shell) microspheres was observed by scanning electron microscopy. The thermal stability of PANI/PMMA particles was examined by use of thermogravimetric analysis. The PANI/PMMA particle-based suspension in silicone oil exhibited typical ER behavior. The conductivity of PANI/PMMA particles was much lower than that of the rod-like PANI.     

Preparation and characterization of polyaniline/polysulfone nanocomposite ultrafiltration membrane

Novel nanocomposite membrane was prepared through the filtration of polyaniline (PANI) nanofiber aqueous dispersion with polysulfone (PS) ultrafiltration (UF) membrane. Scanning electron microscope (SEM) images showed that PANI nanofiber layer was formed on the PS membrane surface. Atomic force microscopy (AFM) analysis indicated that the nanocomposite membrane had rougher surface than the PS substrate membrane. Compared with the PS substrate membrane, the nanocomposite membrane had much better permeability for the good hydrophilicity of PANI nanofiber layer, and had almost the same rejection performance. In addition, the nanocomposite membrane had positive surface potential under acidic condition because PANI could be protonated easily by acid. During the filtration of BSA solution, the nanocomposite membrane showed much better antifouling performance than the substrate membrane for the hydrophilicity and steric hindrance effect of its nanofiber layer. Moreover, under acidic solution condition, strong electrostatic repulsion between PANI nanofibers and BSA existed and improved membrane antifouling performance further.     

喹吖啶酮衍生物/介孔分子筛MCM-41组装体的金属离子传感性能研究

将5,12-二［6-(2-氨基乙基氨基)己基］ 喹吖啶酮(BAEAHQA)组装到介孔分子筛MCM-41的孔道中,制备了金属离子传感材料BEDAHQA /MCM-41. 荧光光谱显示组装体的发光避免了喹吖啶酮固体发光的浓度猝灭现象. 引入不同的金属离子将使BAEAHQA/MCM-41的荧光光谱强度发生不同程度的降低和峰位移动. 尤其是金属钴离子可以使BAEAHQA/MCM-41的发光产生明显的猝灭,猝灭程度可达到92.63％. 通过引入乙二氨基团BAEAHQA达到了发光基团与螯合基团之间的分离,有效地避免了pH值对发光的影响. 实验结果表明,BAEAHQA/MCM-41对于金属离子具有良好的传感特性.