核壳结构在甲烷干重整中的应用

甲烷干重整可以将两种温室气体(CO₂和CH₄)转化为合成气,传统负载型催化剂存在金属烧结、碳沉积的问题,导致失活。核壳结构催化剂具有空间限域效应,能有效解决以上问题。本文根据壳的种类,将核壳结构分为SiO₂壳层、Al₂O₃壳层和其他壳层三类,并分别从制备方法、形貌结构、催化特性的角度介绍了研究现状。文中指出：氧化硅壳层的优势是制备简单,壳层易于调控,热稳定性高;Al₂O₃壳层能够提供碱性位点,增强CO₂吸附与反应;CeO₂壳层则可以提供氧空位,促进CO₂活化和积炭的气化。据此,本文展望了核壳结构在未来的几个研究方向：对壳层材料的拓展与研究;对蛋黄壳、三明治等新型核壳结构的研究;精准调节核壳结构的形态并研究构效关系;大规模制备和工业应用等。     

具有梯级释药性能的核壳型双重载药微球

分别利用单轴和同轴静电喷雾法成功制备出以聚乳酸-羟基乙酸共聚物（PLGA）为内核基质、聚乙烯吡咯烷酮（PVP）为外壳基质的核壳型双重载药微球,其中,抗菌药物盐酸万古霉素（VA）被包封于微球外壳,促成骨药物地塞米松（DA）被负载于微球内核。对载药微球的形貌结构、物理性质和体外释药性能进行了表征和分析。结果表明,当电喷前体PVP浓度为80g/L时,单轴和同轴静电喷雾方法均可得到大小均一、球形良好的核壳型微球。X射线衍射（XRD）和差示扫描量热（DSC）结果表明,DA晶体被成功包封于核壳型微球后转变为无定形状态。基于PVP的水溶性和PLGA的缓慢降解特性,两种核壳型载药微球都实现了壳层VA快速释放、内核DA缓慢释放的梯级释药性能。本文制备得到的具有梯级释药性能的核壳型载药微球在药物控释、组织工程等领域有很好的应用前景。     

核壳结构纳米复合材料的制备及催化应用研究进展

核壳结构纳米复合材料，即一层或多层的无机或有机材料借助某种相互作用力包覆在无机或有机颗粒的外表面所形成的具有核壳结构的纳米材料。核壳结构纳米复合材料可以改善外壳和内核的不足，提高材料的光、电、磁、催化等特性。根据核和壳层的不同可划分出多种分类，且制备方法多样。核与壳之间的相互作用促使核壳结构纳米复合材料呈现出多种优异的功能特性，广泛应用于诸多领域。在催化中，核壳结构纳米复合材料不但表现出良好的耐化学侵蚀特性还能有效减少纳米粒子的团聚、烧结等问题。该文综述了核壳型纳米复合材料的分类、制备方法及在催化领域中的应用，简单阐述了其形成机理，并对其未来发展方向进行了展望。     

核壳结构纳米复合材料的制备及催化应用研究进展

核壳结构纳米复合材料,即一层或多层的无机或有机材料借助某种相互作用力包覆在无机或有机颗粒的外表面所形成的具有核壳结构的纳米材料。核壳结构纳米复合材料可以改善外核和内壳的不足,提高材料的光、电、磁、催化等特性。根据核和壳层的不同可划分出多种分类,且制备方法多样。核与壳之间的相互作用促使核壳结构纳米复合材料呈现出多种优异的功能特性,广泛应用于诸多领域。在催化中,核壳结构纳米复合材料不但表现出良好的耐化学侵蚀特性还能有效减少纳米粒子的团聚、烧结等问题。该文综述了核壳型纳米复合材料的分类、制备方法及在催化领域中的应用,简单阐述了其形成机理,并对其未来发展方向进行了展望。     

Facile synthesis of zirconium phosphonate-functionalized magnetic mesoporous silica microspheres designed for highly selective enrichment of phosphopeptides

In this work, we present a facile approach for the synthesis of zirconium phosphate (ZrP)-functionalized magnetic silica mesoporous microspheres for the selective enrichment of phosphopeptides. At first, magnetic mesoporous silica microspheres were prepared by directly coating mesoporous silica onto Fe3O4 magnetic microspheres, and then addition of phosphate onto the magnetic mesoporous silica microspheres was performed using 3-(trihydroxysilyl)propyl methylphosphate. The obtained phosphate-modified magnetic mesoporous microspheres were monodispersed with a mean diameter of 350 nm, and had an obvious mesoporous silica shell (～65 nm). Finally, the resultant phosphate-functionalized magnetic mesoporous microspheres were incubated in ZrOCl2 solution with gentle stirring overnight for the loading of Zr4+ cations. The obtained Zr4+-functionalized materials were applied to the selective enrichment of phosphopeptides from both standard protein digestion and real samples. The enriched peptides were analyzed by MALDI-TOF MS and LC-ESI MS. Experimental results demonstrated that zirconium phosphonate-modified magnetic mesoporous silica microspheres show excellent potential for the selective enrichment of phosphopeptides.     

Construction of magnetic-targeted and NIR irradiation-controlled drug delivery platform with Fe3O4@Au@SiO2 nanospheres

Near-infrared (NIR) light has great potential in biomedical applications due to its advantages of deep penetration depth and low photodamage to biological tissues. In this paper, we constructed a novel core-shell structured drug nanocarrier, Fe₃O₄@Au@SiO₂, for the controlled delivery of etoposide (VP16), a chemotherapeutic drug for cancer patients. The novel core-shell structured drug delivery platform is composed of a mesoporous silica shell and a magnetic Fe₃O₄ core using Au nanoparticles (AuNPs) as the interlayer, which is characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, N₂ adsorption/desorption isotherms and the magnetic measurements with vibrating-sample magnetometer (VSM). The synergistic effects of AuNPs, mesoporous silica and Fe₃O₄ make the core-shell structured nanocomposites an excellent candidate for targeted and NIR light irradiation-controlled drug delivery. For the proposed nanocarrier of VP16, the mesopores in silica can enhance the encapsulation capacity of the nanocarrier and the AuNPs can effectively convert the NIR light into heat to speed up the drug deliver; meanwhile, the incorporation of Fe₃O₄ with high magnetization to the drug delivery platform realize drug targeting under an applied external magnetic field.     

Formation of dual-responsive polystyrene/polyaniline microspheres with sea urchin-like and core-shell morphologies

In the present work, a simple and effective approach has been employed to fabricate the polystyrene/polyaniline (PS/PANI) composite microspheres with various morphologies. PS/PANI composite microspheres exhibiting different structures such as sea-urchin like, core-shell structure, have been synthesized by seeded emulsion polymerization with polystyrene microspheres as seeds. In particular, the sea urchin-like PS/PANI composite microspheres, with radial array nanofibers on the surface, have demonstrated the switchable wettability between superhydrophilicity (0°) and superhydrophobicity (152°) under the response of either electrical potential or pH. This intelligible approach can produce sea urchin-like PS/PANI composite microspheres in bulk. The growth mechanism of sea urchin-like PS/PANI composite microspheres has also been elucidated. Following the dissolution of the PS template, the sea urchin-like polyaniline (PANI) hollow microspheres are obtained.     

磁性介孔二氧化硅微球的研究及应用进展

磁性介孔二氧化硅微球作为一种新型纳米复合材料,广泛应用于众多领域.综述了近年来磁性介孔二氧化硅微球的制备方法,并对其在靶向药物、生物富集与分离、磁热疗、固定化酶等生化领域的应用作了介绍.     

Designed multifunctionalized magnetic mesoporous microsphere for sequential sorption of organic and inorganic pollutants

A novel magnetic microsphere with thiol-functionalized mesoporous shell was fabricated by using a colloidal chemical method and cationic surfactants (CTAB) as structure-directing agents. As a high performance adsorbent, these microspheres were examined for environmental protection applications to adsorb and remove toxic phenolic compounds and heavy metal ions, sequentially, in aqueous solution. The prepared nanocomposite microspheres were mesoporous and magnetizable, with a diameter of 350-400 nm, a high surface area of 913.14 m²/g, a pore size of 2.48 nm, and a saturation magnetization of 33.9 emu/g. These multifunctional microspheres showed excellent adsorptive capability towards toxic phenolic compounds and heavy metal ions (Hg²⁺, Pb²⁺). The cation micelle made of CTAB in the mesopores has great attractive power to phenolic compounds and the adsorption capacity was as high as 144.78 mg/g for 4-methyl-2,6-dinitrophenol. The thiol-functionalized magnetic mesoporous microsphere (TMMM) which had adsorbed phenolic compounds can further adsorb metal ions after removing CTAB. The adsorption capacity was 185.19 mg/g for Hg²⁺ and 114.7 mg/g for Pb²⁺. The TMMM can be easily removed from solution by an external magnetic field. These results suggest that this kind of nanocomposites is potentially useful materials for effectively adsorbing and removing different dangerous pollutants in aqueous solution.     

Synthesis of mesoporous MOR materials by varying temperature crystallizations and combining ternary organic templates

An approach, which involved perturbations of synthesis conditions in crystallization temperature and organic template composition, has been proposed for derivation of mesopores from bulk structural defects formed in mordenite (MOR) phases, based on the character of intrinsic crystal defects and tensional distortions of two compressed 8-membered rings in MOR framework. Consequently, hierarchically porous materials with MOR structures were prepared by varying temperature synthesis and using ternary organic micelles templates. The synthesized materials were characterized by powder X-ray diffraction, nitrogen adsorption at 77 K and transmission electron microscopy. These crystalline materials combined the advantages of both mordenites with the micropore system and mesoporous materials by featuring an additional intracrystalline mesopore system in MOR single crystals, resulting in a hierarchical pore distribution in range of 1.7-80.0 nm together with the significant specific surface areas. In particular, individual crystal morphologies of typical mesoporous MOR materials showed the defect-rich structures responding essentially to the mesoporosity; the mesoporous materials were substantiated matchable well to normal mordenites in acid capacity and acid strength distribution. Furthermore, several factors acting on intracrystalline mesopore formation were elucidated for explicating the perturbation synthesis approach, and whole reaction routes for synthesizing different solid products under related crystallization conditions were summarized coupling with a demonstration of part TEM micrographs. The overall results suggested that the investigative approach of perturbation imposed on crystal growth provides an alternative route for direct hydrothermal synthesis of mesoporous zeolite materials and implied that bulk structural defects within single crystals lead to the formation of intracrystalline mesopores in various sizes.     

A cationic surfactant assisted selective etching strategy to hollow mesoporous silica spheres

Hollow mesoporous silica spheres have recently attracted increasing attention. However, effective synthesis of uniform hollow mesoporous spheres with controllable well-defined pore structures for fundamental research and practical applications has remained a significant challenge. In this work, a straightforward and effective "cationic surfactant assisted selective etching" synthetic strategy was developed for the preparation of high-quality hollow mesoporous silica spheres with either wormhole-like or oriented mesoporous shell. The as-prepared hollow mesoporous silica spheres have large surface area, high pore volume, and controllable structure parameters. Our experiments demonstrated that cationic surfactant plays critical roles in forming the hollow mesoporous structure. A formation mechanism involving the etching of solid SiO(2) accelerated by cationic surfactant followed by the redeposition of dissolved silica species directed by cationic surfactant is proposed. Furthermore, the strategy can be extended as a general strategy to transform silica-coated composite materials into yolk-shell structures with either wormhole-like or oriented mesoporous shell.     

介孔碳的研究进展及应用

介孔碳是一类新型的具有巨大比表面积和孔体积的介孔材料,可以通过不同的方法合成并对其孔结构和形貌进行调节。本文主要综述了介孔碳及介孔碳基复合材料的合成方法,对比阐述了不同方法制备的介孔碳材料所具备的孔道结构和形貌。介绍了将不同非金属和金属元素及其氧化物掺杂在介孔碳中合成复合材料,发现制备的复合材料具有更优的性能且掺杂元素不同复合材料的形貌和孔道结构不同。此外,简要说明了介孔碳及碳基复合材料在环境、催化、储能、电化学和生物医学等方面的应用,指出其在各个领域的应用仍存在不足。调整介孔碳的孔结构和表面性能、采用更简便易控制的合成方法将成为制备介孔碳及碳基材料的主要研究方向。     

Facile synthesis of silica/polymer hybrid microspheres and hollow polymer microspheres

Monodisperse silica/polydivinylbenzene (SiO₂/PDVB) and silica/poly(ethyleneglycol dimethacrylate) (SiO₂/PEGDMA) core-shell hybrid microspheres were prepared by a two-stage reaction with silica particles' grafting of 3-(methacryloxy)propyltrimethoxysilane (MPS) as core and PDVB or PEGDMA as shell, in which the MPS-modified silica core with diameter of 238 nm was synthesized by Stöber method and subsequently grafted with MPS as the first-stage reaction. The PDVB or PEGDMA shell was then encapsulated over the MPS-modified silica core by distillation precipitation polymerization of divinylbenzene (DVB) or ethyleneglycol dimethacrylate (EGDMA) in neat acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) initiator as the second-stage reaction. The encapsulation of PDVB and PEGDMA on modified silica core particles was driven by the capture of DVB or EGDMA oligomer radicals via the vinyl groups on the surface of the modified silica cores during the second-stage polymerization in the absence of any stabilizer or surfactant. The shell thickness of the core-shell hybrid particles was controlled by the feed of DVB or EGDMA monomer during the polymerization. Hollow PDVB or PEGDMA microspheres with various shell thickness were further developed after selective removal of the modified silica cores with hydrofluoric acid. The resultant core-shell hybrid materials and hollow microspheres were characterized by transmission electron microscopy (TEM), and Fourier transform infrared spectra (FT-IR).     

二氧化硅核壳纳米材料的研究进展

核壳型纳米材料作为一种新型的复合型材料,在内核和外壳的协同作用下,能够发挥出单一材料或合金无法比拟的性能优势。根据组成材料属性的不同可以将核壳纳米材料分为无机/无机、无机/有机、有机/无机和有机/有机核壳材料4大类。介绍了核壳材料的形成机理,主要对以二氧化硅为外壳,以金属、金属氧化物、分子筛为内核的几种无机核壳材料的最新研究成果及应用进行了综述。最后,对核壳材料未来的发展前景进行了展望。     

Mesoporous silica–magnetite nanocomposites: Fabrication, characterisation and applications in biosciences

Template assisted fabrication of magnetic mesoporous silica–magnetite nanocomposites and their performance in binding and elution of Salmon sperm DNA has been reported. The effect of reaction pH (10–2) during the fabrication of nanocomposites has been studied. All materials fabricated at various pH were characterised by XRD, TEM, FT-IR, nitrogen adsorption and magnetic susceptibility measurements. Fabrication at neutral pH (7) in the presence of a cationic surfactant (cetyl trimethyl ammonium bromide; CTAB) produced core–shell nanocomposites of quasi spherical and rod shaped morphologies with mesoporous (pore size 3.5 nm) silica shell and rhombic magnetite core. Fabrication at alkaline pH (10) produced monolithic mesoporous silica composites with embedded magnetite nanoparticles. Fabrication at acidic pH (4 and 2) produced a biphasic mixture of rhombic magnetite and amorphous silica rods. A similar fabrication at acidic pH (2) in the absence of CTAB produced a biphasic mixture of rhombic magnetite and spherical silica nanoparticles. All materials exhibited a high value of Salmon sperm DNA binding at physiological pH whereas elution value of DNA was observed to be dependent on the extent of silica coating on magnetite nanoparticles.     

磁性漆酚缩甲醛微球的制备与表征

在共沉淀法合成磁流体的基础上,用悬浮缩聚法制备了磁性漆酚缩甲醛微球,并用X射线粉末衍射、透射电镜和热重分析等对微球进行结构表征。实验结果表明,Fe3O4磁流体的粒径为纳米量级,纳米Fe3O4粒子能够提高复合物的热性能。该微球粒径约1mm,是核壳结构,具有良好的耐溶剂性和耐热性。     

An overview of ordered mesoporous material SBA-15: synthesis,functionalization and application in oxidation reactions

Ordered mesoporous materials are attracting wide concern because of their applications in the field of catalysis, adsorption, separations, drug delivery systems and gas sensors owing of their extremely high surface area combined with well-defined pore structures with narrow pore size distributions. Various mesoporous materials such as MCM-41, MCM-48, SBA-15 and SBA-16 have been reported in past two decades. Synthesis of mesoporous materials involves the concept of aggregation of surfactants as structure directing agents under acidic or basic conditions. The dimensions of these mesopores can be obtained by type of surfactant, auxiliary chemicals and synthesis conditions. At present, SBA-15 has attracted more attention among different mesoporous silica structures due to their desirable properties such as thick pore wall and hexagonal mesopores (4–12 nm), high surface area, ease of synthesis and functionalization and high thermal and mechanical stability. In last few years, great effort has been made on the development of various methods for the synthesis of mesoporous materials as support for oxidation reactions. The aim of this review article is to focus mainly on mesoporous SBA-15 together with its application as support for various oxidation reactions.     

介孔碳微球的合成及其应用研究进展

目前,介孔碳微球的合成主要有硬模板和软模板两种方法。硬模板是将碳前驱体通过溶剂挥发填充到已合成的球形介孔材料(硬模板)中,然后热处理掉硬模板得到介孔碳微球;软模板则是以三嵌段共聚物F127做为模板剂,酚醛树脂作为碳源在水热条件下制备出介孔碳微球。介孔碳微球在超级电容、锂离子电池、气体储存、生物医药等领域获得广泛应用,然而在摩擦润滑领域的研究却未见报道。结合本课题组的前期研究提出了其在摩擦领域的研究思路并展望了其应用前景。     

Design Strategy for the Multilayer Core–Shell Bioceramics with Controlled Chemistry

New strategies for fabricating multiphase bioceramic porous scaffolds with time‐dependent biodegradation and pore network enlargement are of fundamental importance in the advancement of bioceramics. Here, we developed a one‐step preparation of core–shell bioceramic microspheres (~2 mm in diameter) with single‐ or double‐shell structure through a coaxially aligned multilayer capillary system. The Ca‐phosphate (CaP) and Ca‐silicate (CaSi) ceramic phase distribution could be also adjusted by extruding through different capillaries, and thus the biodegradation rate would be readily tailored over time. When the polystyrene (PS) microbeads of ~15 μm in diameter were premixed into the CaP‐ or CaSi‐containing alginate slurry, the tailorable porous structures could be introduced into the core or different shell layers of the microspheres. These micropores may potentially maximize the permeability for rapid exchange of guest molecules or inorganic ions from the bioceramics. Totally, such strategy is promising because the ceramic phases with different biological properties can be assembled into the core–shell bioceramic microspheres, and thus the macropore structure evolution may be readily manipulated in the closely packed microsphere systems. We believe our gradient hybrid methodology will have potential in various categories of advanced biomaterials of organic–inorganic composites.     

Formation of Sn filled CNTs nanocomposite: Study of their magnetic,dielectric properties and enhanced microwave absorption performance at gigahertz frequencies

The Simplistic formation, advantageous configuration, non-colossal magnetoresistance and broadband absorption are important parameters for microwave absorbent materials. In this study, a core-shell nanocomposite comprising of Sn-filled carbon nanotubes (Sn/CNTs) was prepared by arc discharge method. The microstructure, morphology and surface composition of Sn/CNTs-based core-shell nanocomposites were characterized in detail. Sn/CNTs nanocomposite showed a magnetic signal due to the broken bonds and defects at interfaces in Sn/CNTs. The weak ferromagnetism was found to be helpful in improving magnetic permeability in the Sn/CNTs which confirms its role as a magnetic loss material under incident electromagnetic wave. Sn-filled CNTs revealed an appropriate value of dielectric constant, which plays an important role in impedance matching upon incident electromagnetic wave. The composite of Sn-CNTs and paraffin with a 50 wt % loading showed the lowest reflection loss (RL) of ?43.87 dB at 10 GHz, with a wide effective absorption band (RL ≤ ?10 dB) of 3 GHz in thickness of 2.3 mm. This enhanced performance is attributed to the combined effect of the conduction loss in one-dimensional core-shell architecture, the interfacial loss Sn-CNT interface, the magnetic loss due to defects-induced ferromagnetism in Sn shell, and in the carbon-containing atomic layers of CNTs.