Synthesis and characterization of Ag/polyaniline core-shell nanocomposites based on silver nanoparticles colloid

Ag/polyaniline core-shell nanocomposites were successfully synthesized via in situ chemical oxidation polymerization of aniline based on mercaptocarboxylic acid capped Ag nanoparticles colloid. The morphology and structure of the products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and UV-Vis spectra. A possible formation mechanism of the Ag/polyaniline core-shell nanocomposites was also proposed.     

聚苯乙烯/银核壳结构纳米微球的制备与表征

采用两步法的简单路线制备出银纳米粒子包覆的聚苯乙烯(PS)微球,首先通过乳液聚合法合成出聚苯乙烯微球;然后对苯乙烯进行敏化和活化,搅拌下加入银的还原液,从而制备出Ag-PS核壳结构的纳米微球.同时借助于TEM、UV-vis、 FE-SEM进行表征,分析其微观结构.结果表明,所得的聚苯乙烯微球粒径约为40nm;聚苯乙烯/银核壳结构纳米微球粒径为45～350nm,银层厚度可随意调控.     

Microwave-assisted ionic liquid preparation and characterization of cellulose/calcium silicate nanocomposites in ethylene glycol

Preparation of cellulose-based nanocomposites by microwave-assisted ionic liquid method allows the high value-added applications of cellulose by combining three major green chemistry principles: using environmentally preferable solvents, environmentally friendly method and renewable biomaterials. In this paper, we report the microwave-assisted ionic liquid method for the fast controlled synthesis of the cellulose/calcium silicate nanocomposites by using the microcrystalline cellulose, Ca(NO₃)₂·4H₂O and Na₂SiO₃·9H₂O in ethylene glycol. The calcium silicate nanoparticles were homogeneously dispersed in the cellulose matrix. The experimental results showed that the additive of ionic liquid favored the composite of cellulose and calcium silicate. The weight loss of nanocomposites was decreased with the increasing ionic liquid concentrations. The influences of heating times, heating temperatures, and ionic liquid concentrations on the products were investigated. This method is fast, environmentally friendly and suitable for the large-scale production of cellulose-based nanocomposites.     

核壳型纳米Au@Ag复合材料的制备、催化及光抑菌

以纳米Au为核，在其表面负载Ag合成核壳型纳米Au@Ag复合材料，利用TEM、EDX、UV-Vis对材料进行表征。以甲基橙为目标污染物研究材料的催化加氢活性，并初步探讨其催化机制；用革兰氏阴性菌大肠杆菌(E.coli)和革兰阳性菌金黄色葡萄球菌(S.aureus)为模式菌研究材料的光抑菌活性和抑菌机制。结果表明，相比纳米Ag,纳米Au@Ag在8 min内对甲基橙的降解率为99%以上，加氢产物为对氨基苯磺酸钠和对二氨基苯；抑菌实验证明：相比黑暗环境中，300 W光照下的纳米Au@Ag具有更强的抑菌性能，在浓度为300μg/mL,光照10 min下的抑菌效率更高，并对细菌的迟缓期和对数期的生长阶段作用较为明显，对E.coli的细胞壁破坏较为严重。     

Synthesis and characterization of core-shell structural MWNT-zirconia nanocomposites

Core-shell structural MWNT/ZrO2 nanocomposites were successfully prepared by one-step hydrolyzing of MWNT-dispersed ZrOCl2.8H2O aqueous solution. A highly conformal and uniform monoclinic zirconia coating was deposited on MWNTs by this new and simple method, and the thickness of the coating increased with the reaction time.     

核壳结构TiO2/Ag反蛋白石的制备与形貌观察

用化学还原法制备了银包覆聚苯乙烯(PS)微球结构,通过垂直沉积法排列出具有密堆积结构的PS-Ag蛋白石模板,然后采用溶胶-凝胶法渗透TiO2,最后焙烧处理除去PS,制备出了规整的核壳结构TiO2/Ag反蛋白石。采用扫描电镜、透射电镜和X射线衍射对该样品进行了分析。结果表明,PS球表面包覆的为纳米尺度的金属Ag;所制备的PS/Ag核壳微球蛋白石经过480℃、12h焙烧处理后获得的核壳TiO2/Ag反蛋白石结构的单胞参数可以通过调节包覆银层的厚度来调变,即改变AgNO3与PS球的质量比获得具有不同银包覆层厚度、不同单胞参数的三维蛋白石和反蛋白石结构。     

Synthesis and characterization of the tellurium/calcium silicate nanocomposite

A novel tellurium/calcium silicate nanocomposite with tellurium nanorods homogeneously dispersed in the calcium silicate matrix has been successfully synthesized using corresponding tellurium nanorods, Ca(NO₃)₂·4H₂O, and Na₂SiO₃·9H₂O in ethanol/water mixed solvents at room temperature for 48 h. The new material consists of a single crystalline Te core and an amorphous calcium silicate shell. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDS). The method is simple and does not need any surfactant or template or base. Cytotoxicity experiments indicated that the tellurium/calcium silicate nanocomposites with a low concentration had good biocompatibility. This nanocomposite is a very promising candidate for the application as bioactive materials.     

Fabrication and characterization of perovskite ferroelectric PMN/PT ceramic nanocomposites

The potential of a ceramic nanocomposite technique employing a simple bimodal particle size packing and a pressureless sintering process as a low-cost and simple ceramic processing to obtain perovskite ferroelectric ceramics in the PMN/PT system was demonstrated. Attention was focused on relationships between chemical composition, densification, microstructure, and electrical properties. It has been found that the phase formation, microstructures, and dielectric properties of ceramic nanocomposites are totally different from those of typical solid solutions.     

Synthesis,characterization, and dispersion behavior of ZnO/Ag nanocomposites

ZnO/Ag nanocomposites that are composed of quasi-spherical nanoparticles with diameters of several nanometers have been successfully generated by a two-step liquid precipitation method. The as-prepared ZnO/Ag nanocomposites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM). The dispersion behaviors of the ZnO/Ag nanocomposites in isopropanol with using nonionic dispersants such as stearic acid, PVP K17, and PVP K30 were investigated by conventional sedimentation method, dynamic light scattering method (DLS) and TEM observation. Both the PVP K17 and PVP K30 could disperse the ZnO/Ag nanoparticles effectively in isopropanol. It is proposed that the nonionic dispersants could form absorbed PVP molecule layers on the surfaces of the ZnO/Ag nanoparticles, prohibiting their agglomeration and enhancing their dispersion stability in isopropanol. This work is helpful for further investigating the potential applications of ZnO/Ag nanocomposites in the fields of medical plastics and sterilization.     

HA-n-ZrO2核壳层复合陶瓷微粉材料的制备与表征

采用水热-沉积原位分步反应法.制备了羟基磷灰石(HA)-氧化锆(ZrO2)复合微粉,采用XRD和TEM对复合微粉的物相、形貌和大小进行了表征.对复合微粉进行模压成型、热处理制备了复合陶瓷试样,并测试其力学性能.结果表明:所得复合微粉以纳米级四方相ZrO2为"核心",逐层包覆HA,形成核-壳层结构(HA-n-ZrO2);...     

Synthesis and characterization of Ag/polypyrrole nanocomposites based on silver nanoparticles colloid

Ag/polypyrrole nanocomposites were successfully synthesized via in situ chemical oxidation polymerization of pyrrole based on mercaptocarboxylic acid capped Ag nanoparticles colloid. Scanning electron microscopy (SEM) measurement showed that the obtained Ag/polypyrrole nanocomposites were spherical. Transmission electron microscopy (TEM) measurement showed that the Ag nanoparticles were inside the polypyrrole particles and had a little aggregation. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra were used to characterize the structure of the obtained Ag/polypyrrole nanocomposites. A possible formation mechanism of the Ag/polyrrole nanocomposites was also proposed.     

Fabrication and characterization of elastomeric polyester/carbon nanotubes nanocomposites for biomedical application

A novel biodegradable polymer elastomer nanocomposite composing of poly(1,8-octanediol-citrate) (POC) polymer matrix and carbon nanotubes (CNTs) additive was successfully fabricated and systematically investigated using Fourier transform infrared (FT-IR), X-ray diffractometer (XRD), differential scanning calorimetry (DSC), tensile test, incubation and cytotoxicity tests. It was found that the addition of CNTs in POC elastomer did not result in any noticeable change in its chemical structure and the amorphous state. However, the tensile strength and elongation at break were greatly improved by the addition of CNTs in POC polymer matrix. It revealed that the swelling ratio and percentage of weight loss of POC/CNTs nanocomposite were lower, compared with the pure POC material. Moreover, the adsorption amount of bovine serum albumin (BSA) increased with an increase of the CNTs mass content in POC matrix revealing the enhanced hydrophilicity of POC/CNTs nanocomposites contributed by the carboxyl of the CNTs. Additionally, the cytotoxicity tests with L929 cell line revealed that the experimental POC/CNTs nanocomposites possessed good in vitro biocompatibility.     

Fabrication of Ag/PVA nanocomposites and their potential applicability as dielectric layer in thin film capacitor

Over the past decade, polymer–metal nanocomposites have drawn a great deal of attention due to their extensive application in organic flexible devices. Here, we describe the synthesis and characterisation of silver–polyvinyl alcohol nanocomposite thin films and investigates the possibility of application of these composite films as dielectric layer in efficient capacitors. The material characterisation is done through UV–vis absorption, scanning electron microscopy and atomic force microscope. The dielectric property of the nanocomposite material is investigated with a LCR meter. The different fabricating parameters for generating homogeneous thin films are optimised in this investigation. The composite material thin films exhibit high capacitance density and low dielectric loss and hence they may be suitable ingredients for high capacitance capacitors.     

Fabrication and characterization of porous calcium polyphosphate scaffolds

Porous calcium polyphosphate (CPP) scaffolds with different polymerization degree and crystalline phases were prepared, and then analyzed by scanning electron microscopy (SEM), Thermmogravimetry (TG) and X-ray diffraction (XRD). Number average polymerization degree was calculated by analyzing the calcining process of raw material Ca(H₂PO₄)₂, as a polycondensation reaction. Amorphous CPP were prepared by the quenching from the melt of Ca(H₂PO₄)₂ after calcining, and CPP with different polymerization degree was prepared by controlling the calcining time. Meanwhile, CPP with the same polymerization degree was prepared to amorphous or different crystalline phases CPP which was made from crystallization of amorphous CPP. In vitro degradation studies using 0.1 M of tris-buffered solution were performed to assess the effect of polymerization degree or crystalline phases on mechanical properties and weight loss of the samples. With the increase of polymerization degree, the weight loss during the degradation decreased, contrarily the strength of CPP increased. The degradation velocity of amorphous CPP, α-CPP, β-CPP and γ-CPP with the same polymerization degree decreased in turn at the same period. The full weight loss period of CPP can be controlled between 17 days and more than 1 year. The results of this study suggest that CPP ceramics have potential applications for bone tissue engineering.     

Preparation and characterization of multifunctional magnetic mesoporous calcium silicate materials

Abstract

We have prepared multifunctional magnetic mesoporous Fe–CaSiO₃ materials using triblock copolymer (P123) as a structure-directing agent. The effects of Fe substitution on the mesoporous structure, in vitro bioactivity, magnetic heating ability and drug delivery property of mesoporous CaSiO₃ materials were investigated. Mesoporous Fe–CaSiO₃ materials had similar mesoporous channels (5–6 nm) with different Fe substitution. When 5 and 10% Fe were substituted for Ca in mesoporous CaSiO₃ materials, mesoporous Fe–CaSiO₃ materials still showed good apatite-formation ability and had no cytotoxic effect on osteoblast-like MC3T3-E1 cells evaluated by the elution cell culture assay. On the other hand, mesoporous Fe–CaSiO₃ materials could generate heat to raise the temperature of the surrounding environment in an alternating magnetic field due to their superparamagnetic property. When we use gentamicin (GS) as a model drug, mesoporous Fe–CaSiO₃ materials release GS in a sustained manner. Therefore, magnetic mesoporous Fe–CaSiO₃ materials would be a promising multifunctional platform with bone regeneration, local drug delivery and magnetic hyperthermia.     

New advances in polymer/layered silicate nanocomposites

This review discusses some recent advances in polymer silicate nanocomposites. In particular, we highlight the properties of specific nanocomposites while emphasizing the lack of properties trade-offs in these systems. We also present our work on the structure and dynamics of the polymer/nanofiller interface and attempt to relate them to macroscopic nanocomposite properties.     

纳米尺度PS/Ag核壳结构复合球的制备与表征

采用分步法制备了聚苯乙烯/银(PS/Ag)核壳结构复合纳米球。首先采用无皂乳液聚合法并利用丙烯酸(AA)的羧基对制备的PS球进行改性,使其表面带负电荷;然后通过静电吸附作用在改性PS球的表面沉积[Ag(NH3)2]+,水浴(80℃)环境中利用十二烷基磺酸钠(SDS)作为还原剂将PS球表面的[Ag(NH3)2]+还原,制备出PS/Ag核壳结构复合球。通过动态激光粒度分析仪和透射电子显微镜对PS/Ag核壳纳米球的粒度分布、形貌和结构进行了表征,研究了AA的用量对复合球粒径及包覆的Ag壳厚度的影响。结果表明,随着AA用量的增大,所包覆的银层更加致密,厚度增大,当AA用量为15%时可得到Ag完全包覆的PS/Ag复合纳米球。     

Fabrication of mesoporous calcium silicate/calcium phosphate cement scaffolds with high mechanical strength by freeform fabrication system with micro-droplet jetting

In this study, we explored the feasibility of fabrication bioactive mesoporous calcium silicate/calcium phosphate cements (MCS/CPC) scaffolds with high mechanical strength by Freeform Fabrication System with Micro-Droplet Jetting. After preparation of ordered mesoporous calcium silicate (MCS) powder, ready-to-use MCS/CPC paste was formed by mixing calcium phosphate cement (CPC) powder and MCS powder with the binder polyvinyl alcohol (PVA) aqueous solution at a certain ratio of powder to liquid. MCS/CPC scaffolds with various architectures, pore sizes, and interconnectivity were then directly printed at room temperature using MCS/CPC paste. The mechanical strength, apatite formation, degradation rate, and cytocompatibility of the composite scaffolds were systematically investigated. The results showed that MCS/CPC paste exhibited outstanding printability to form MCS/CPC scaffolds. The hybrid MCS/CPC scaffolds with predefined pore size of 350 μm showed fast degradation rate, high mechanical strength, and good cytocompatibility. It was indicated that the hybrid MCS/CPC scaffolds might be a promising candidate for critical bone defect repair.     

Fabrication and characterization of electrospun Ag doped TiO2 nanofibers for photocatalytic reaction

Titanium dioxide is one of the best semiconductor photocatalysts available for photocatalytic reaction of dye pollutants. To prevent the recombination caused by the relatively low photocatalytic efficiency, Ag doped TiO₂ nanofiber was prepared by electrospinning method. The photocatalysts (pure TiO₂ nanofiber and Ag doped TiO₂ nanofiber) were characterized by FE-SEM, XRD, XPS, and PL analysis. These photocatalysts were evaluated by the photodecomposition of methylene blue under UV light. Ag doped TiO₂ nanofiber was found to be more efficient than pure TiO₂ fiber for photocatalytic degradation of methylene blue. The photocatalytic degradation rate was applied to pseudo-first-order equation. The degradation of Ag doped TiO₂ nanofiber was significantly higher than the degradation rate of pure TiO₂ nanofiber. Activation energy was calculated by applying Arrhenius equation from the rate constant of photocatalytic reaction. The activation energies for the pure TiO₂ nanofibers calcined at 400 and 500 °C were 16.981 and 12.187 kJ/mol and those of Ag doped TiO₂ nanofibers were 18.317 and 7.977 kJ/mol, respectively.