超声场中高分子乳液稳定性与多孔材料结构的调控机理研究

采用星型聚合物POSS-（PMMA）₈作为乳化剂兼成膜基质,使用超声乳化法制备w/o型聚合物乳液,制备的乳液液滴初始直径受超声功率调控,阐明了超声功率对液滴直径大小的作用规律.结果表明乳液液滴直径呈双峰分布,且随超声功率的增大液滴直径增大.通过改变水相离子浓度制备聚合物乳液,得到的乳液液滴直径10 μm左右且单分散性好,并发现随超声功率增大乳液的絮凝程度增大.探索了超声功率对乳液失稳机制的影响,当超声功率低于750 W时,奥氏熟化是乳液失稳的主要机制.通过浸渍法制备以玻璃纤维为基底的多孔膜材料,发现多孔材料的孔径变化与对应乳液的液滴直径变化基本一致.本研究证实了通过改变超声功率可以调控乳液的液滴直径,然后利用乳液模板法能获得结构和形貌可控的多孔材料.     

微量热法研究非离子型表面活性剂微乳液

用微量热法研究了由正十六烷／正己醇／水／烷基聚氧乙烯醚组成的微乳液中水的状态，对微乳液中水的模式对热效应的影响进行了解释。在微乳液具有异常流变性的水油比范围内，测定了体系在负触变性状态恢复期间的热效应。     

MOFs在乳液中的可控生长

金属有机框架(Metal organic frameworks, MOFs)材料是金属离子与有机配体自组装形成的形貌可控的多孔晶体材料。表面活性剂的乳化作用是形成乳液的关键,其自组装形成不同形貌的胶束控制最终产物的形貌。因此,在MOFs的制备中,不同乳液体系中的胶束亦可以作为反应模板,从而调控MOFs的形貌。本文简要介绍了传统乳液、反相微乳液、无皂乳液和Pickering乳液的形成机理和特点。重点综述了近年来MOFs在不同乳液体系中可控生长研究。其中,利用无皂乳液法和Pickering乳液法是构建MOFs复合材料的理想思路。     

微乳液反应法制备聚甲基丙烯酸甲酯超细粒子

水/油微乳液;微乳液反应法制备聚甲基丙烯酸甲酯超细粒子     

微乳液法制备介孔碳材料

介孔碳材料因具有高比表面积,规则的孔隙结构,低密度,良好的生物相容性及导电性,被广泛应用于催化、能量储存及转化、吸附分离和药物递送等领域。微乳液法具有制备工艺简便、环境友好、可大规模生产及产物结构可控性强等突出优势,在制备孔隙结构可控和特殊形态介孔碳方面取得突破性的进展。本文首先着重分析了微乳液法制备介孔碳的反应机理,包括微乳液诱导协同组装机制、乳液溶胀效应和微流控液滴技术。其次,进一步探讨了控制介孔碳材料孔隙形态、外部形貌及内部结构的影响因素。最后,对新型介孔碳材料在能源储存与转化、催化、吸附以及药物递送领域的应用进行了归纳,并对未来的发展提出了展望。     

乳液法制备球形锰酸锂及其影响因素

文章介绍了目前锂离子电池正极材料球形化制备的情况，对乳液法二次造粒的方法及其机理进行了初步探讨。以微波合成法制备的LiMn2O4作为一次颗粒，采用一种特殊的乳液法二次造粒，初步制备了球形LiMn2O4正极材料。对二次造粒的产物进行了SEM、XRD分析，测试了其振实密度，发现在二次造粒过程中一次颗粒有一定生长，二次颗粒球状形貌还不够理想，分析了原因，为进一步研究打下基础。     

铈锆固溶体制备方法的研究进展

铈锆固溶体具有优良的储释氧性能,在三效汽车尾气净化催化剂中起着重要作用,而铈锫固溶体的制备方法与其物化性质又有着密切联系.综述了近几年来国内外铈锆固溶体的制备方法(包括共沉淀法、模板剂法、溶胶-凝胶法、微乳液法等).讨论了晶相结构、比表面积、热稳定性等对固溶体储释氧性能的影响,通过分析固溶体的程序升温还原(TPR)谱图,解释了不同制备方法对所得铈锆固溶体氧化-还原能力的差异.结合文献结果,可以认为寻找工艺简单、性能稳定、重复性好的可控制备方法将是此类材料得到大规模应用的努力方向.     

聚氨酯/聚丙烯酸酯复合乳液的研制进展

概述聚氨酯－聚丙烯酸酯复合乳液的制备方法。特别对聚氨酯－聚丙烯酸酯复合乳液共聚法作了较为系统的介绍和讨论。     

纳米微粒的微乳液制备法

Ｗ／Ｏ微乳液制备纳米微粒是一新兴的研究领域。本文系统地介绍了乳浮液制备法的基本原理、微乳液“水池”中纳米微粒的鉴定方法、目前该领域的研究进展，并提出了适用于制备纳米微粒的微乳液体系的选择标准及该领域研究工作的展望。     

高聚物水基微乳液的研究进展

阐述了高聚物水基微乳液的定义，乳化原理和高聚物乳化的途径。对近十几年来高聚物水基微乳液研究的状况，影响微乳液的因素，乳化机理及应用前景进行了综述。     

General synthesis of hollow composite ellipsoids

A facile and general approach towards composite hollow ellipsoids has been proposed. The parent polystyrene (PS) hollow spheres are embedded in a matrix, for example, poly(vinyl alcohol), and stretched into the corresponding ellipsoids. The aspect ratio of the ellipsoids is tunable by stretching extent. Accordingly, sulfonated PS hollow ellipsoids are achieved by sulfonation of the PS hollow ellipsoids, which will facilitate an easy complexation with functional materials. Composite hollow ellipsoids, with varied composition ranging between polymer, metal and oxides, and inorganic materials, are synthesized against the polymer ellipsoids as templates. By controlling growth of the functional materials at specific sites, structure of the composite hollow ellipsoids is controlled such as surface-pillared, single-shelled and double-shelled. This approach avoids traditional removal of polymer templates, thus guarantees the shell integrity of the composite hollow ellipsoids.     

Hollow latex particles: synthesis and applications

One of the major developments in emulsion polymerization over the last two decades has been the ability to make hollow latex particles. This has contributed many fundamental insights into the synthesis and the development of structure in particles. Hollow latex particles also enhance the performance of industrial coatings and potentially are useful in other technologies such as microencapsulation and controlled release. Ever since the publication of the initial process patents describing these particles, there has been a global R&D effort to extend the synthetic techniques and applications. One prominent synthetic approach to hollow particles is based on osmotic swelling. This dominates the literature, and usually starts with the synthesis of a structured latex particle containing an ionizable core that is subsequently expanded with the addition of base. Fundamental to this approach are a sophisticated control of transport phenomena, chemical reactivity within the particle, and the thermoplastic properties of the polymer shell. Hydrocarbon encapsulation technology has also been employed to make hollow latex particles. One approach involves a dispersed ternary system that balances transport, conversion kinetics, and phase separation variables to achieve the hollow morphology. Other techniques, including the use of blowing agents, are also present in the literature. The broad range of approaches that affords particles with a hollow structure demonstrates the unique flexibility of the emulsion polymerization process.     

Confining the Sol-Gel Reaction at the Water/Oil Interface: Creating Compartmentalized Enzymatic Nano-Organelles for Artificial Cells

Living organisms compartmentalize their catalytic reactions in membranes for increased efficiency and selectivity. To mimic the organelles of eukaryotic cells, we develop a mild approach for in situ encapsulating enzymes in aqueous-core silica nanocapsules. In order to confine the sol-gel reaction at the water/oil interface of miniemulsion, we introduce an aminosilane to the silica precursors, which serves as both catalyst and an amphiphilic anchor that electrostatically assembles with negatively charged hydrolyzed alkoxysilanes at the interface. The semi-permeable shell protects enzymes from proteolytic attack, and allows the transport of reactants and products. The enzyme-carrying nanocapsules, as synthetic nano-organelles, are able to perform cascade reactions when enveloped in a polymer vesicle, mimicking the hierarchically compartmentalized reactions in eukaryotic cells. This in situ encapsulation approach provides a versatile platform for the delivery of biomacromolecules.     

一种制备单分散SiO2空心微球的新方法

在乙醇/氨水介质中, 分别以分散聚合和无皂乳液聚合方法制得的不同粒径聚苯乙烯(PS)微球为模板, 以正硅酸乙酯(TEOS)为前驱体, 通过控制介质中氨水的初始体积, 一步法制得了不同粒径的单分散SiO2空心微球. 整个过程无需添加其它溶剂溶解或高温煅烧的方法来除去模板微球. 对SiO2空心微球进行测试表征, 提出了SiO2空心微球的可能形成机制.     

ZnO-based hollow microspheres with mesoporous shells: Polyoxometalate-assisted fabrication, growth mechanism and photocatalytic properties

With the assistance of Keggin-type polyoxometalate, ZnO hollow microspheres with mesoporous shells were synthesized via a simple solvothermal approach without any templates and surfactants. The observations of morphology and structure performed by field emission scanning electronic microscopy and transmission electron microscopy indicated that the shells of the ZnO hollow spheres were built from nanosheets which were composed of nanoparticles. The transformation of structure and composition of samples were investigated by X-ray diffraction, X-ray photoelectron spectrometry and fourier transform infrared absorption spectroscopy. The formation mechanism of the hollow spheres is proposed based on time-dependent experimental results. The ZnO hollow microspheres exhibited a high photocatalytic activity for decolorization of Rhodamine B under ultraviolet irradiation.     

无机有机-核壳材料研究进展

综述了近年来各种核壳材料的合成方法,包括聚合法layer-hy-layer(LbL)自组装技术、原位反应法等。并简要介绍了空心材料的制备及核壳材料的应用。     

In situ generated dense shell-engaged Ostwald ripening: A facile controlled-preparation for BaFe12O19 hierarchical hollow fiber arrays

This paper describes a simple and convenient approach to fabricate BaFe₁₂O₁₉ hierarchical hollow fibers or hollow fiber arrays by heat-treating electrospun solid fibers or fiber arrays using a deliberately devised two-step heat-treatment process, in which the dense shells generated in situ during the short-time pre-treatment procedure direct Ostwald ripening of flake-shaped BaFe₁₂O₁₉ nanocrystals in the elevated temperature heat-treatment procedure. The heat-treatment temperature has a strong effect on the structure and magnetic properties of the BaFe₁₂O₁₉ hierarchical hollow fibers and the resulting BaFe₁₂O₁₉ hierarchical hollow fiber arrays show a slight magnetic anisotropy as well as high coercivity. The in situ generated dense shell-engaged directing Ostwald ripening approach reported here can be readily extended to fabricate other metal oxides hollow fibers, and the resulting BaFe₁₂O₁₉ hierarchical hollow fibers or hollow fiber arrays are promised to have use in a number of applications that involve microwave absorber, magnetic separation, and so forth.     

Controllable Synthesis of Hollow Multishell Structured Co3O4 with Improved Rate Performance and Cyclic Stability for Supercapacitors

Hollow multishelled structures(HoMSs)Co3O4 with specially appointed shell number(double-,triple-and quadruple-)were accurately prepared by a sequential templating approach.Due to the superiorities of inimitable porous multishelled structure,triple-HoMSs Co3O4 achieved the best performance among all the samples with a specific capacitance of 1028.9 F/g at 10 mV/s and 688.2 F/g at 0.5 A/g,respectively.Furthermore,the electrode delivered a high rate performance(89.8%retention at 10 A/g)and excellent cycle stability(6.8%loss over 2000 cycles),showing a great promise for practical application in the future.     

Fabrication of polystyrene–PbS core-shell and hollow PbS microspheres with sulfonated polystyrene templates

Uniform inorganic- (PbS) coated polymer core-shell and hollow PbS microspheres were prepared by an easy and economical approach. Monodisperse polystyrene (PS) microspheres were used as templates, as well as the core of the composite spheres; lead sulfide shells were obtained through the reaction of lead acetate (Pb(CH₃COO)₂) and thioacetamide (TAA) at room temperature. The morphologies and structures of the as-synthesized products were systematically characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectra (FTIR). The fluorescence property of the as-synthesized product was also investigated. A reasonable mechanism for the formation of PS–PbS core-shell and hollow PbS microspheres was discussed. According to a series of parallel experiments, effects of related experimental parameters were also carefully investigated, such as the molar ratio of Pb(CH₃COO)₂ to TAA, reaction temperature, etc.     

Fabrication of hollow titania microspheres with tailored shell thickness

Submicron hollow spheres are an interesting class of materials that receive significant attention nowadays. Closed and mechanically robust homogeneous hollow titania microspheres with as much shell thickness as 130 nm were fabricated by coating polystyrene beads with titania nanoparticles using sol–gel chemistry and subsequently removing the core either via heating or a chemical dissolution process. The thickness of the titania shell deposited on polystyrene core was finely tuned between 100 and 130 nm by varying the concentration of titania precursor, i.e., Ti(OEt)₄ salt from 0.5 to 2 mM during the coating process. The obtained hybrid core–shell particles and hollow microspheres were characterized by scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray diffraction, and thermo-gravimetric analysis. The approach employed is well suited to the preparation of titania-coated polystyrene hybrid particles and hollow titania spheres, which can find their applications as novel building blocks with unique optical properties for fabrication of advanced materials, catalyst, and drug delivery system.