Janus粒子的制备及功能化应用

Janus粒子是指表面具有两种或两种以上不同化学组成或性质的不对称粒子,目前Janus粒子的制备方法仍在发展中,同时也逐渐形成了Janus粒子在生物医药、催化、材料以及防污等领域功能化应用的研究重点。本文从Janus粒子制备和应用两个方面方法来介绍Janus粒子的研究进展。制备方法主要包括表面选择性修饰法、晶种生长法、微流控法、嵌段共聚物自组装法和电化学沉积法等。应用方面则着重介绍了Janus粒子在生物医药、界面催化、表面活性剂、复合材料、微米马达和防污等方面的功能化应用,并对Janus粒子未来的发展趋势做了展望。     

纳米粒子组装体系的研究进展

制备纳米粒子组装体系是构筑纳米结构的重要方法之一，本文综述了纳米粒子组装体系的制备方法及其性质和应用研究。     

金核银壳纳米粒子薄膜的制备及SERS活性研究

采用柠檬酸化学还原法制备金溶胶, 通过自组装技术在石英片表面制备金纳米粒子薄膜, 在银增强剂混合溶液中反应获得金核银壳纳米粒子薄膜. 用紫外-可见吸收光谱仪和原子力显微镜(AFM)研究了不同条件下制备的金核银壳纳米粒子薄膜的光谱特性和表面形貌, 并以结晶紫为探针分子测量了金核银壳纳米粒子薄膜的表面增强拉曼光谱(SERS). 结果表明, 金纳米粒子薄膜的分布、银增强剂反应时间的长短对金核银壳纳米粒子薄膜的形成均有重要影响. 制备过程中, 可以通过控制反应条件获得一定粒径的、具有良好表面增强拉曼散射活性的金核银壳纳米粒子薄膜.     

以胶体粒子为模板制备核壳纳米复合粒子

核壳纳米复合粒子具有许多不同于单组分胶体粒子的独特的光、电、磁、催化等物理与化学性质,是构筑新型功能复合材料的重要组元,在光子带隙材料、微波吸收材料、电磁流变液、催化剂和生物等领域有重要应用.本文从控制核壳复合粒子的微观结构及壳层均匀性与厚度的角度,详细评述了目前以胶体粒子为模板制备粒径从纳米到微米尺度的核壳复合粒子的方法.指出利用胶体粒子模板表面与壳层物质或其前驱物间的特殊相互作用(包括静电和化学相互作用),是完善现有制备方法和发展新方法来制备具有设定组成、结构和性能的核壳复合粒子的关键,同时也是将来的粒子表面纳米工程和获取有序的、先进纳米复合材料的主要方向。     

乳液聚合法制备纳米金/聚苯乙烯复合粒子

以氯金酸为前驱体,十二烷基硫醇和硼氢化钠分别作为稳定剂和还原剂,采用相转移法制备了单分散的金纳米粒子.将金纳米粒子通过乳液聚合的方法制备了纳米金/聚苯乙烯复合粒子.通过紫外-可见吸收光谱(UV-Vis)研究了纳米金和纳米金/聚苯乙烯复合粒子的光吸收特性,使用傅立叶变换红外光谱(FT-IR)、X射线衍射(XRD)、透射电子显微镜(TEM)和动态光散射(DLS)对产物的组成、晶体结构、形貌、以及粒径进行了表征.结果表明,复合粒子为粒径分布较窄的球形,其中的金纳米粒子为面心立方结构.热失重分析(TGA)说明制备的纳米金/聚苯乙烯复合粒子具有很好的热稳定性.     

sol-gel 法在有机-无机杂化体系中制备二氧化硅微粒

利用sol-gel法,通过正硅酸乙酯（tetraethyl orthosilicate（TEOS））在聚氧化乙烯／二甲基甲酰胺溶液中水解、缩聚,制备了粒径分布均匀的微米级二氧化硅粒子;利用扫描电子显微镜观测了制备条件对二氧化硅粒子的粒度和形貌的影响;研究了这一方法在制备无机粒子过程中的原理．     

基于微流控技术制备微/纳米粒子材料

具有特殊性质的微/纳米粒子,在药物传递、吸收分离、光电材料和磁性设备等多个领域具有重要的应用价值。近年来,微流控技术在有机合成、高分子化学以及材料制备等领域表现出传统釜式反应器无法比拟的优势。本文介绍了基于微流控技术制备微/纳米粒子的最新研究进展,包括以单乳液为模板合成球形和非球形聚合物粒子、无机物粒子、贵金属纳米粒子和半导体纳米粒子,以多重乳状液为模板制备壳核粒子、Janus粒子和微囊。     

双面粒子的制备及应用研究进展

双面粒子是指粒子的两个半球表面具有不同组成或性质的微粒.这种各向异性或不对称的结构使其有很广泛的应用,但也使其制备变得困难.近年来已发展了很多制备方法,本文总结了最近几年双面粒子在制备及应用方面的研究进展.     

超细均分散稀土化合物胶体粒子制备

利用尿素分解法制得轻、中、重稀土化合物的超细均分散胶体粒子,详细探讨了浓度、pH值、陈化温度、陈化时间及共存阴离子等因素对制备过程的影响,获得了各种粒子的最佳制备条件.     

DDP修饰铜超微粒子的制备

本文在非水溶剂中用液相还原法制备出DDP修饰的铜超微粒子，对制备条件作了初步探讨．Cu－DDP超微粒子的表征结果表明其粒径小、分布均匀，且在有机溶剂中有较好的分散性，显示出良好的润滑应用前景。     

微乳液聚合制备聚 N-异丙基丙烯酰胺温敏超细微粒

通过微乳液聚合制备了未交联及交联的聚N 异丙基丙烯酰胺 (L PNIPAM及CL PNIPAM)超细微粒 .CL PNIPAM的聚合动力学方程为 :Rp=k[M]1 1 6 [E]- 1 2 0 [I]0 5 3.测得其平均微粒粒径约 10 0nm .用SEM ,迎头色谱法测得交联的CL PNIPAM超细微粒的内比表面积为 49 0 48m2 g ,孔径大小为 1～ 10nm .气体吸附量为1784 8cm3 g .用浊度法及目视法研究了其在水介质中的温敏特性 ,测得其相变温度为 31 5℃     

含不同氨基酸反相微乳体系中胆红素钙的形成与稳定性

在聚乙二醇辛基苯基醚(OP)/正己醇/环己烷/水反相微乳液和甘氨酸、精氨酸、组氨酸3种含不同氨基酸的反相微乳液体系中成功地制备了胆红素钙,考察了氨基酸对胆红素钙的组成、形貌、配位方式及稳定性的影响。采用透射电子显微镜、表面Zeta电位、红外光谱和紫外光谱等测试技术对样品进行了表征。结果表明,此反相微乳体系中所得球形颗粒为中性胆红素钙,平均粒径80nm,在水分散体系中颗粒的稳定性随分散体系pH值的升高而先降低后增加,当pH=4.9时,颗粒表面Zeta电位值为0。3种亲水性氨基酸的加入促进胆红素钙颗粒的成核,最终影响胆红素钙的微结构、颗粒形貌和稳定性。当加入的氨基酸为组氨酸、甘氨酸时,所得胆红素钙球形颗粒形貌无明显变化,但平均粒径依次减小至60和40nm,其水分散体系中的稳定性明显增加;当加入的氨基酸为精氨酸时,所得胆红素钙颗粒形貌不规则,粒径非常小,不稳定,易形成聚集体。     

壳聚糖/聚丙烯酸纳米粒子对蛋白质的吸附行为

以马来酸酐改性的壳聚糖(MAH-chitosan)和丙烯酸(AA)为单体,采用反相微乳液聚合法制备了AA含量分别为77%(AA-Cs)和29%(Cs-AA)壳聚糖/聚丙烯酸复合纳米粒子。TEM结果表明,该复合纳米粒子平均粒径为125~150nm,进而研究了其对牛血红蛋白(Hb)、牛血清白蛋白(BSA)和溶菌酶(Ly)吸附和脱附行为。AA-Cs对各种蛋白的吸附量均较高;而Cs-AA对3种蛋白的吸附则具有一定选择性。AA-Cs对等电点低于脱附pH值的Hb的脱附量较大。Cs-AA粒子在较低pH值(pH=3.4)时对吸附有利,但在高pH值(pH=6.6)进行吸附时,对脱附更为有利。     

Novel one-step route for synthesizing CdS/polystyrene nanocomposite hollow spheres

CdS/polystyrene nanocomposite hollow spheres with diameters between 240 and 500 nm were synthesized under ambient conditions by a novel microemulsion method in which the polymerization of styrene and the formation of CdS nanoparticles were initiated by gamma-irradiation. The product was characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA), which show the walls of the hollow spheres are porous and composed of polystyrene containing homogeneously dispersed CdS nanoparticles. The quantum-confined effect of the CdS/polystyrene nanocomposite hollow spheres is confirmed by the ultraviolet-visible (UV-vis) and photoluminescent (PL) spectra. We propose that the walls of these nanocomposite hollow spheres originate from the simultaneous synthesis of polystyrene and CdS nanoparticles at the interface of microemulsion droplets. This novel method is expected to produce various inorganic/polymer nanocomposite hollow spheres with potential applications in the fields of materials science and biotechnology.     

In Situ Immobilization of Ultrafine Particles Synthesized in a Water/Oil Microemulsion

We investigated the in situ immobilization of ultrafine particles synthesized in a water/oil (w/o) microemulsion to silica for its possible application to supported metal catalysts. ZnS particles immobilized to silica by the ME method were consistent with those synthesized in a w/o microemulsion. Therefore, ZnS particles in a w/o microemulsion could be immobilized to silica without aggregation by this method. The relationship between the method of synthesizing Rh ultrafine particles in a w/o microemulsion and the diameter and diameter distribution of Rh particles immobilized to silica was studied. Rh-SiO(2) catalysts with a sharp diameter distribution could be prepared by immobilizing Rh-hydrazine complex particles because these complex particles would be very stable in a w/o microemulsion. The Rh particle diameters of Rh-SiO(2) catalysts prepared by changing the amount of silica produced were almost identical. Accordingly, the Rh particle diameter of Rh-SiO(2) catalysts could be controlled independently of Rh content by the ME method. Copyright 2001 Academic Press.     

Semicontinuous microemulsion polymerization

Batch microemulsion polymerization is a process that allows the synthesis of oil-soluble and water-soluble nanoparticles, nanocomposites and nanogels smaller than ca. 50 nm with larger molecular weights (ca. 10⁷ g/mol); however, the large amounts of surfactant required by this process to produce small amounts of polymer have hindered its industrial scaling. Semicontinuous O/W and W/O microemulsion polymerizations allow increasing the polymer content without adding more surfactant to the original reacting formulation. The several schemes of semicontinuous microemulsion polymerization that have been proposed, semibatch, semicontinuous feeding or lot additions of monomer to the reacting microemulsion, are reviewed here. Semicontinuous inverse microemulsion polymerization, which is a process to synthesized water-soluble polymer nanoparticles that have important applications as superabsorbents and flocculants, are also reviewed. Moreover, alternative processes, denoted by our group as normal and inverse semicontinuous heterophase polymerizations, which allows the synthesis of even larger concentration of polymer employing smaller amounts of surfactant compared to microemulsion polymerization, are examined.     

Microemulsion polymerization of acrylamide and styrene: Effect of the structures of reaction media

Isothermal phase diagrams of the system cetyltrimethylammonium bromide (CTAB)/n‐butanol/n‐octane/water were constructed, and the effect of the oil (n‐octane) contents on the microemulsions was studied at 40 °C. We determined the microemulsion structures of two systems, CTAB/n‐butanol/10% n‐octane/water and sodium dodecyl sulfonate (As)/n‐butanol/20% styrene/water, by conductivity measurements to investigate the polymerization of acrylamide and styrene in the two microemulsion systems. The polymerization kinetics of the water‐soluble monomer acrylamide in CTAB micelles and the different CTAB/n‐butanol/10% n‐octane/water microemulsion media [water‐in‐oil (W/O), bicontinuous (BC), and oil‐in‐water (O/W)] were studied with water‐soluble sodium bisulfite as the initiator. The maximum polymerization rate in CTAB micelles was found at the second critical micelle concentration. A mechanism of polyacrylamide formation and growth was proposed. A connection between the structures of the microemulsions and the polymerization rates was observed; the maximum polymerization rate occurred at two transition points, from W/O to BC and from BC to O/W, and the polyacrylamide molecular weights, which depended on the structures of the microemulsions, were also found. A square‐root dependence of the polymerization rates on the initiator concentrations was obtained in CTAB micelles and O/W microemulsion media. The polymerization of the oil‐soluble monomer styrene in different As/n‐butanol/20% styrene/water microemulsion media (W/O, BC, and O/W) was also investigated with different initiators: water‐soluble potassium persulfate and oil‐soluble azobisisobutyronitrile. A similar connection between the structures of the microemulsions and the conversions of styrene in CTAB/n‐butanol/10% n‐octane/water for the polymerization of acrylamide was observed again. The structures of the microemulsions had an important role in the molecular weights and sizes of polystyrene. The polystyrene particles were 10–20 nm in diameter in BC microemulsion media and 30–60 nm in diameter in O/W microemulsion media according to transmission electron microscopy. We determined the solubilization site of styrene in O/W microemulsion drops by ¹H NMR spectra to analyze the results of the microemulsion polymerization of styrene. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3320–3334, 2001     

Inverse microemulsion polymerization of oil-soluble monomers in the presence of hydrophilic polyacrylamide nanoparticles

A new method for preparation of modified polymer particles in two steps was proposed. Free radical polymerization of an oil soluble vinyl monomer like butyl acrylate in inverse microemulsion containing polyacrylamide particles led to the formation of modified, partly hydrophobized, polyacrylamide particles. For the first step of the process (preparation of polyacrylamide particles in inverse microemulsion) is typical a very high polymerization rate while for the second step (polymerization of an oil soluble monomer (methyl acrylate, ethyl acrylate, butyl acrylate 2-ethylhexyl acrylate, methyl methacrylate, styrene) in the presence of polyacrylamide particles in inverse microemulsion, the reverse is true. The polymerization of an oil soluble monomer in some instances leads to the formation of 2-phase or even 3-phase disperse systems. The polymeric products obtained after precipitation of the polymer particles from the inverse microemulsions by ethanol were extracted by water and/or toluene and analyzed for acrylamide content. The separated polymer product contained high content of acrylamide, AAm/oil soluble monomer (butyl acrylate BA, or styrene, S) copolymer (85% of AAm/BA, ≈ 99% of AAm/S) besides relatively small amounts of homopolymers of oil soluble monomers (15% of BA, ≈ 1% of S homopolymers).     

Preparation of polystyrene nanoparticles including fluorescent and hydrophobic materials by polymerization at phase inversion temperature

The polystyrene nanoparticles incorporating hydrophobic and fluorescent pyrene was successfully prepared by a direct polymerization at phase inversion temperature. The average diameter of the prepared polystyrene nanoparticles is around 30 nm or less: 22 nm. This preparation does not require any strong agitation, which is necessary for the usual mini‐emulsion polymerization, and does not need the large amount of surfactant as much as the usual microemulsion polymerization. The incorporation of pyrene in the prepared polystyrene particles was confirmed by fluorescence spectra. This developed method is superior to the addition of pyrene to polystyrene particles prepared, which causes large coagulum and gives polystyrene particles with lower weight fraction of pyrene. The developed method is expected to be applicable for preparation of polymer particles including various hydrophobic materials. Copyright © 2014 John Wiley & Sons, Ltd.     

磁性聚苯胺纳米微球的合成与表征

报道了具有核壳结构的Fe3O4-聚苯胺磁性纳米微球的合成方法和表征结果.微球同时具有导电性和磁性能.在优化的实验条件下,可得到饱和磁化强度Ms为55.4 emu/g,矫顽力Hc为62 Oe的磁性微球.微球的导电性随着微球中Fe含量的增加而下降.微球的磁性能则随着Fe含量的增加而增大.Fe3O4磁流体的粒径和磁性聚苯胺微球的粒径均在纳米量级.纳米Fe3O4粒子能够提高复合物的热性能.实验表明,磁流体和聚苯胺之间可能存在着一定的相互作用,但这种相互作用较为复杂,难于研究