核壳结构碳化钨复合微球催化剂对甲醇电催化性能

以偏钨酸铵微球为前驱体,在不同反应时间和CO/CO₂气氛条件下,通过原位还原碳化反应制备了具有核壳结构碳化钨复合微球。采用X射线粉末衍射（XRD）、X射线光电子能谱（XPS）和扫描电镜（SEM）等对催化剂的形貌和结构进行了表征分析。硼氢化钠还原法将平均粒径为4.6 nm的Pt纳米粒子均匀分布在其表面,得到核壳结构碳化钨复合催化剂。采用循环伏安和计时电流法研究了在酸性溶液中催化剂对甲醇的电催化氧化性能。结果表明,与Pt/WC-15 h和JM Pt/C催化剂的电化学性能相比,Pt/WC-6 h催化剂对甲醇呈现出更高的电催化氧化活性和稳定性。碳化钨复合微球表面少量WO₂成分的存在有利于甲醇在其表面的电催化氧化过程的发生。     

应用于氧还原反应的石墨烯-无定形碳核壳结构复合材料载铂催化剂(英文)

采用氯化法制备石墨烯-无定型碳复合材料(GNS@a-C),并用作质子交换膜燃料电池(PEMFC)氧还原反应Pt催化剂的载体.结果显示,所制Pt/GNS@a-C催化剂与传统商业催化剂Pt/C相比,有较好的活性和较高的稳定性:质量活性(0.121 A/mg)几乎是Pt/C(0.064 A/mg)的两倍.更重要的是,该新型催化剂加速4000圈后其电化学活性面积保留了最初的51%,与Pt/C的33%相比,前者有更好的电化学稳定性,显示它在PEMFC中将具有较好的应用潜力.     

核壳结构纳米粒子

纳米粒子由于具有大量的潜在应用,近年来已引起人们极大的关注。通过表面改性(如制备核壳结构的纳米粒子)可以使其获得更多特殊的性质。本文就最近几年制备壳核结构纳米粒子的方法进行了总结,根据其核、壳的不同材料进行了分类,并对其中某些方法进行了比较。     

Organized cryogel composites with 3D hierarchical porosity as an extraction adsorbent for nucleosides

Macroscopic monoliths are highly desirable in many fields of application. Herein, well organized organic–inorganic cryogel composite with a three‐dimensional hierarchical meso‐ and macroporous structure are presented, which were produced by in situ copolymerization of mesoporous multifunctional silica (size: 1–20 μm; pore: 2–20 nm mostly) and monomers (hydroxyethyl methacrylate and diallyldimethylammonium chloride) in water below the freezing point. This copolymerization method effectively adjusted the macropores of the basic cryogel, and the nanosilica was more homogeneously dispersed in the basic cryogel. The specific surface area of the cryogel composite was increased 17 times versus than that of the basic cryogel. The abundant meso‐ and macroporous pores on the cryogel composite provided sufficient reactive sites favorable for the efficient mass transport of target compounds. When the cryogel composite, as solid phase extraction adsorbent, was coupled with high‐performance liquid chromatography, an analytical tool, the nucleosides were quantified with good selectivity, lower detection limits (0.9–1.3 ng/mL) and satisfactory recoveries of greater than 80% from spiked human serum.     

核壳结构型阻燃剂研究进展

通过微胶囊化技术可赋予阻燃剂以特殊的核壳结构,从而有效减小阻燃剂吸湿性,增加与基体相容性,明显提高阻燃高分子复合材料力学、耐水、阻燃等性能.本文扼要论述了核壳结构型卤系、氢氧化镁、红磷、无机磷系、有机磷系以及膨胀阻燃体系的研究现状,并阐述了该特殊阻燃剂的研究重点与发展趋势.     

Synthesis of Octylmethoxycinamate-silica Core-shell Nanoparticles with Self-templating Method

A self-templating method was employed to synthesize core-shell nanoparticles with octylmethoxycinamate(OMC), a well-known organic UV absorber, as core and nanosilica particles as shell. The characteristic of this method is that the whole process requires neither surface treatment for nanosilica particles nor additional surfactant or stabilizer, and all the reactions could be finished in one-pot, which exempts removing template and reduces reaction steps compared to the conventional process. The morphology, structure, particle size distribution, chemical composition and optical property of OMC-SiO2 nanoparticles were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), dynamic light scattering(DLS), FTIR spectrometry and UV absorption spectrometry, respectively. Experiment results indicate that the resulting OMC-SiO2 nanoparticles were perfectly spherical with smooth particle surfaces, and had clear core-shell structures. The particle size could be tuned by altering reaction conditions. In addition, the mechanism of the self-templating method for forming core-shell nanoparticles was discussed.     

Fabrication of superhydrophobic surfaces with hierarchical structure through a solution-immersion process on copper and galvanized iron substrates

Superhydrophobic surfaces were obtained on copper and galvanized iron substrates by means of a simple solution-immersion process: immersing the clean metal substrates into a methanol solution of hydrolyzed 1H,1H,2H,2H-perfluorooctyltrichlorosilane (CF3(CF2)5(CH2) 2SiCl3, FOTMS) for 3-4 days at room temperature and then heated at 130 degrees C in air for 1 h. Both of the resulting surfaces have a high water contact angle (CA) of larger than 150.0 degrees as well as a small sliding angle (SA) of less than 5 degrees . The formation and structure of the superhydrophobic surfaces were characterized by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectrometry (EDX). SEM images showed that both of the resulting surfaces exhibited special hierarchical structure. The special hierarchical structure along with the low surface energy leads to the high surface superhydrophobicity.     

Electrical properties of polymeric composites based on nanocrystalline tin dioxide modified with copper iodide

Electrical properties of synthesized nanostructured materials based on nanocrystalline tin dioxide modified with copper iodide and polychlorotrifl uoroethylene were studied. It was shown that the complex dielectric permittivity in the microwave range and the low-frequency electrical conductivity of the polymeric composites depend on the copper iodide concentration on the surface of tin dioxide and reach the maximum values at a volume fraction of CuI of about 0.5. The percolation thresholds were determined for the three-component system. Their values increase from 0.04 to 0.05 vol. fraction as the content of copper iodide in the CuI/SnO₂ system is raised from 0.04 to 0.6 vol. fraction.     

核-壳复合微球的异相凝聚及其表面包覆率调控

提出了一种通过乳化剂复配简便制备表面包覆率可调的核-壳复合微球的方法.高效液相色谱和zeta电位测试结果表明,核粒子和壳粒子在分散混合过程中出现了乳化剂吸附和脱附的再平衡现象,从核粒子表面游离的阳离子乳化剂与壳粒子表面的阴离子乳化剂发生电性中和作用,导致核、壳2种粒子的zeta电位值互相接近,基于静电作用的异相凝聚失效.进一步研究发现,在保持核粒子分散液中乳化剂总量为1 wt%的前提下,添加非离子乳化剂既可以确保分散体系的稳定性,又可以调控阳离子乳化剂的游离量,成功实现核-壳复合微球的异相凝聚.由此可见,通过调节复配乳化剂中阳离子与非离子乳化剂的配比,可简便地调控复合微球的表面包覆率.还探讨了异相凝聚体系中pH值和电解质浓度对核-壳复合微球表面包覆率的影响.     

Room temperature synthesis of curved ammonium copper molybdate nanoflake and its hierarchical architecture

A new strategy has been successfully designed to synthesize curved ammonium copper molybdate [(NH(4))(2)Cu(MoO(4))(2)] nanoflakes on a copper surface by employing a novel solution-phase approach at room temperature. This method consists of a liquid-solid reaction between Na(2)MoO(4) solution and the copper substrate itself in the assistance of formamide. The lamellar ammonium copper molybdate are approximately perpendicular to the copper substrate surface and are intermeshed with each other to form nanogroove structures. Formamide molecules cannot only promote the oxidation of copper substrate and the formation of copper complex, but also act as a NH(4)(+) source in the final products. Furthermore, the selective adsorption of formamide molecules on different crystallographic planes of ammonium copper molybdate plays the major role in determining the curved morphology. In addition, using glucose as additives to control the nucleation and growth process (through a stepwise nucleation mechanism) can lead to a hierarchical sphere-like architecture.     

Core-shell Molecular Imprinted Polymer Colloids

Molecular imprinted core-shell colloidal polymer particles have been prepared in which the shells were formed, in aqueous media, in the presence of organic templates. The most selective system involved the use of an unsaturated alkyl phosphate as the electrostatic binding motif. Systems that were able to selectively differentiate between caffeine and theophylline and the Gly-Gly sequence in tripeptides are described. Radiotracing experiments showed that all of the caffeine template could be removed following extraction.     

核壳型含氟丙烯酸酯共聚物的合成及性能

采用饥饿态半连续种子乳液聚合方法, 在十二烷基硫酸钠(SDS)/辛基苯基聚氧乙烯醚(TX-10)复合乳化剂的作用下, 分别选用甲基丙烯酸三氟乙酯(TFEM)、甲基丙烯酸六氟正丁酯(HFBM)和甲基丙烯酸十二氟庚酯(DFHM)为含氟单体, 合成以丙烯酸正丁酯(BA)、甲基丙烯酸甲酯(MMA)和含氟单体为原料的核壳型结构含氟丙烯酸酯共聚物乳液. FTIR, 1H NMR, TEM和DSC分析结果显示, 获得了BA/MMA/含氟单体的共聚物乳液, 且乳液具有明显的核壳结构. DSC, TGA和SEM-EDX的分析显示, 核壳型结构的共聚物具有优异的热力学稳定性能和成膜性能; 长侧链或短侧链含氟单体对共聚物的热稳定性影响不明显, 但侧链较长的含氟单体所获得的聚合物在成膜过程中更易向表面迁移, 更能体现含氟聚合物的优点.     

Core-shell nanoparticles coated with molecularly imprinted polymers: a review

Core-shell surface molecular imprinting technology represents a rather new trend in analytical sciences. In this kind of material, the imprinting sites are located on the surface of the cores or shells of nanoparticles (NPs). This material can improve the capability of recognizing target molecules (analytes), reduce nonspecific adsorption, increase the relative adsorption capacity and selectivity, and accelerate the rate of mass transfer. This review (with 158 references) focuses on recent trends in core-shell MIPs. Following an introduction into the field, a first main section covers common core-materials including silica, magnetic NPs, quantum dots (including semiconductor quantum dots and carbon dots), gold and silver nanoclusters, and up-conversion materials. A further section covers the materials and reagents required for preparing MIPs (with subsections on templates, functional monomers, cross-linkers, initiators, and effects of solvent). A next main section covers synthetic approaches such as precipitation polymerization, emulsion polymerization, and grafting approach. A final section gives examples for applications of core-shell MIPs in analytical assays and in sensing.

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Graphical abstract This review (with 158 references) focuses on recent trends in core-shell nanoparticles coated with molecularly imprinted polymers (core-shell MIPs). Three significant synthesis methods are introduced: precipitation, emulsion and grafting approach. Applications of core-shell MIPs concentrate on solid phase extraction, fluorescent probe, surface-enhanced Raman scattering-based sensors and electrochemical sensors.

     

Core-shell fibrous vascular grafts with the nitric oxide releasing property

Small-diameter vascular grafts with the nitric oxide(NO) releasing property were designed and prepared.Diazeniumdiolated N,N'-dibutyl-1,6-hexanediamine(DBHD/N2O2) was first synthesized as the NO donor and doped into the biocompatible polymer poly(ε-caprolactone)(PCL).The fibrous vascular grafts were fabricated by electrospinning.Despite the reduced platelet adhesion observed on the NO releasing grafts,the cytotoxicity and burst release were apparent,especially at a higher loading level of the NO donor.In or...     

Thermal properties of multilayer graphene and hBN reinforced copper matrix composites

The unique properties of graphene make it a very attractive application, although there are still no commercial products in which graphene would play a key role. Good thermal conductivity is undoubtedly one of the attributes which can be easily used both in materials involving large monoatomic layers, that are very difficult to obtain, as well as multilayer graphene flakes, which have been commercially available on the market for several years. The article presents the results of tests on the characteristic thermal properties of composites with the addition of 2–15% of multilayer graphene (MLG) crystals. The motivation of the study was literature reports showing the possibility of increasing the thermal conductivity of composites with MLG participation in the copper matrix. Since the production of composites with increased properties is associated with obtaining a strong orientation of the flakes in the structure, composites with hBN flakes exhibiting significantly worse but also directional thermal properties were produced for comparison. The paper showed a strong influence of flake morphology on the possibility of creating a directional structure. The obtained Cu/MLG composites with the addition of only 2% MLG were characterized by an increase in the thermal conductivity coefficient of about 30% in relation to sinters without the participation of MLG.

     

同轴静电纺丝法制备具有核-壳纤维结构的多功能敷料

利用同轴静电纺丝制备了具有核壳结构纳米纤维的未交联敷料,其中纤维内核为载有抗菌药物莫匹罗星的聚己内酯(PCL),外壳则由载有麻醉剂利多卡因的胶原构成;通过京尼平将胶原外壳交联后得到交联敷料.用扫描电子显微镜(SEM)和透射电子显微镜(TEM)观察了未交联敷料的表面形貌和纤维的核壳结构.体外药物释放实验结果表明,在2种敷料中,2种药物在1 h内均出现了突释现象,而在随后的60 h中,2种药物均能从敷料中缓慢释放出来,说明2种敷料均具有较好的持续止痛与抗菌性能.二辛可宁酸(Bicinchonininc acid,BCA)蛋白测试结果表明,未交联敷料外壳上的胶原蛋白能够持续地释放出来.体外细胞培养结果表明,与交联敷料相比,未交联敷料能够更好地促进成纤维细胞L929的黏附和生长,具有更好的促进伤口愈合作用.体外抗菌实验结果显示,负载了莫匹罗星的2种敷料的抗菌性能均明显高于对照组,具有良好的抗菌性能.     

Activation and structural and adsorption features of activated carbons with highly developed micro-, meso- and macroporosity

Three sets of activated carbons (ACs) were prepared with the same precursor but activated differently (by CO₂ or water vapour) with various burn-off levels. The ACs demonstrate increased deviation of the pore shape from the slitshaped model with increasing burn-off and contributions of pores of different sizes depending on the activation type. Significant re-arrangement of adsorption complexes, especially of the Van der Waals type characteristic for nonpolar or weakly polar adsorbates (H₂, CH₄, CH₂Cl₂, CHCl₃), occurs in both micropores and mesopores of ACs with decreasing temperature. The behaviour of their mixtures with water and DMSO can strongly differ from that of individual adsorbates.     

多层核-壳结构复合微球材料制备研究进展

基于不同组分的核芯材料制备多层核-壳结构复合材料的独特优势在于可实现对复合材料的尺寸、形态及组成的有效调控,从而获得多类具有新颖结构和性能的多功能复合材料.根据常见核芯材料的组成类型,将核芯材料分为无机纳米颗粒(如磁性微粒、二氧化硅、纳米金属、半导体等)和聚合物微球(如聚苯乙烯和聚合物微凝胶)两类,并分别从多层核-壳复合微球材料的制备方法特点及其性能等方面进行分析和阐述.