Synthesis and Characterization of Magnetic Polymer Microspheres

In this study, amino group–modified magnetic polymer microspheres were synthesized in a well‐shaped spherical form with a size range of 0.6 μm to 0.8 μm by mini‐emulsion polymerization. The morphology, composition, and thermal properties of the magnetic polymer microspheres were characterized by infrared (IR) spectra, transmission electron microscopy (TEM) photographs, particle size analysis, and thermogravimetric analysis (TGA) spectra. The results demonstrate that acrylic acid used for stabilizing the reaction system greatly affects the particle size, magnetite contents, and thermal stability of magnetic polymer microspheres.     

Controlled synthesis of selenium of different morphologies at room temperature

A facile and convenient chemical precipitation route has been developed for the controlled growth of selenium nanowires and hierarchical microspheres at room temperature, with Na₂SeO₃ and hydrazine hydrate as starting materials in the presence of 1,2,3‐trimethylimidazolium tetrafluoroborate (tmimBF₄). The surface morphology of microspheres can be tuned by adjusting the reaction media. The products were characterized by X‐ray powder diffraction (XRD) and scanning electron microscope (SEM). Possible formation mechanisms of selenium nanowires and microspheres are proposed, respectively. The influences of the nature of reaction media, agitation and tmimBF₄ on the morphologies development were experimentally investigated and it was found that these factors were of great importance for the formation of Se morphologies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Large‐scale production of nitrogen‐ and oxygen‐containing activated carbon microspheres for supercapacitors

A main issue in the production of robust supercapacitors is the creation of efficient and cost‐effective electrodes. We present here the realization of a kind of nitrogen‐ and oxygen‐containing activated carbon microspheres made from divinylbenzene, diallyl phthalate, and acrylonitrile monomers, which can be produced on a large scale for use in supercapacitors. The supercapacitor's performance is optimized by adjusting the carbonization temperature of the microspheres. Our preliminary result shows that the supercapacitor displays a maximum capacitance of 300 F/g at the current density of 1.0 A/g and retains ~82% of the capacitance after 10,000 charge–discharge cycles.     

Pd/PdO纳米复合微球的合成及催化性能

采用甲基丙烯酸锌加速还原氯化钯(PdCl₂) 溶液中的钯离子(Pd ²⁺)为钯(Pd) 纳米微球, 进而用得到的钯纳米微球直接制备钯/氧化钯(Pd/PdO) 纳米复合微球. 通过扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 粉末X射线衍射分析(XRD)及X射线光电子能谱分析(XPS) 等方法对 Pd/PdO 纳米复合微球进行表征, 结果表明, 制备的纳米复合微球为表面粗糙、 大小均一的纳米微球. 采用紫外-可见吸收光谱(UV-Vis) 等方法考察了 Pd/PdO 纳米复合微球在对硝基苯酚(4-NTP) 还原反应中的催化性能, 发现其具有良好的催化活性和循环稳定性.     

Thermoresponsive hydrophobic copolymer grafted on agar microspheres for all‐aqueous bioseparations

Agar microspheres were prepared by water–oil emulsification and cross‐linked under alkaline condition. The thermoresponsive hydrophobic copolymer, poly(N‐isopropylacrylamide‐co‐lauryl methacrylate‐co‐acrylamide), was grafted on the agar microspheres via atom transfer radical polymerization. The agar microspheres grafted with copolymers were characterized by light microphotography, elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy. The chain lengths and hydrophobic monomer ratio of the grafting linear polymer had significant effects on the hydrophobicity and adsorption capacity of agar microspheres at different temperatures. The thermoresponsive microspheres were used for separation of proteins and showed binding and release behavior by change of temperatures without change in mobile phase composition. Thus, we suggest thermoresponsive agar microspheres as an alternative separation media for all‐aqueous bioseparations.     

Synthesis and Characterization of Cobalt-Carbon Core-Shell Microspheres in Supercritical Carbon Dioxide System

研究了钴碳核壳微球在超临界二氧化碳体系中的合成过程. 在密闭的不锈钢高压反应釜中,适量的二茂钴和干冰在350 oC下,反应12 h后合成直径大约1 μm的钴碳核壳微球。通过X射线衍射、X射线光电子谱、透射电子显微镜、傅利叶红外光谱(FT-IR)以及拉曼光谱的分析,钴碳核壳微球是由直径小于1 μm的非晶钴核和厚度约为200 nm的非晶碳壳组成. 其生长机理可能是：二茂钴在超临界二氧化碳体系中的热分解,带单电子的碳原子或基团由于磁性作用沉积在磁性的钴核上. 由于非晶碳壳的存在,钴碳核壳微球的磁饱和强度141.     

Poly(vinylphosphonate)s functionalized polymer microspheres via rare earth metal‐mediated group transfer polymerization

We demonstrate a facile, yet efficient method for the functionalization of crosslinked polystyrene (PS) microspheres with biocompatible poly(vinylphosphonate)s via the combination of a UV grafting polymerization and a surface‐initiated group transfer polymerization. Self‐initiated photografting and photopolymerization of ethylene glycol dimethacrylate results in direct photografting of poly(ethylene glycol dimethacrylate) on the PS microspheres with dangling methacrylate functionalities, which are used to immobilize ytterbocene complexes to form the surface‐bound rare‐earth metal catalyst system. The surface‐initiated GTP of dialkyl vinylphosphonates from the initiator system leads to the functionalization of PS microspheres with poly(vinylphosphonate) brushes. Polymerization kinetic investigation indicates that surface‐initiated GTP leads to a constant and remarkably rapid weight gain of the microsphere (a microsphere weight increase of 600% within 3 min), owing to the highly living and efficient character of GTP. The surface‐initiated GTP occurring inside the microsphere causes an accumulation of the tension between the polymer chains in the microsphere, which eventually induces fracture of the microsphere for longer polymerization time. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2919–2925     

ZnIn2S4 flowerlike microspheres embedded with carbon quantum dots for efficient photocatalytic reduction of Cr(VI)

Development of efficient heterostructured photocatalysts that respond to visible light remains a considerable challenge. We herein show the synthesis of ZnIn₂S₄/carbon quantum dot hybrid photocatalysts with flowerlike microspheres via a facile solvothermal method. The ZnIn₂S₄/carbon quantum dot flowerlike microspheres display enhanced photocatalytic and photoelectrochemical activity compared with that of pure ZnIn₂S₄. With a content of only 0.5 wt % carbon quantum dots, 93% of Cr(VI) is reduced under visible-light irradiation at 40 min. As a co-catalyst, the carbon quantum dots improve the light absorption and lengthen the lifetime of charge carriers, consequently enhancing the photocatalytic and photoelectrochemical activity.     

Pseudomonas sp. Lipase Immobilized on Magnetic Porous Polymer Microspheres as an Effective and Recyclable Biocatalyst for Resolution of Allylic Alcohols

Magnetic porous polymeric microspheres containing epoxy groups were prepared by suspension polymerization (denoted as magnetic Fe₃O₄@GEM microspheres). Fe₃O₄@GEM with a specific surface area of 30.41 m²/g, average pore diameter of 17.13 nm, and pore volume of 0.13 cm³/g exhibited superparamagnetic behavior with the saturation magnetization of 7.1 emu/g. The content of epoxy groups on Fe₃O₄@GEM was 0.22 mmol/g. Pseudomonas sp. lipase (PSL) was covalently immobilized onto the Fe₃O₄@GEM microspheres through the reaction between the amino groups of the enzyme and the epoxy groups on the microspheres. PSL/Fe₃O₄@GEM exhibited enhanced enantioselectivity for the resolution of allylic alcohol to the corresponding optically active (S)‐allylic alcohol and (R)‐allylic alcohol acetate compared to free PSL. The enantiomeric excess of (S)‐l‐pheny‐2‐propen‐1‐ol for the former (98.1%) was 81.7 times that of the latter (1.2%) when the immobilized PSL was used for transesterification resolution of (R,S)‐l‐pheny‐2‐propen‐1‐ol. Furthermore, the ee_s and ee_p values were still retained at 95.2% and 95.4% after PSL/Fe₃O₄@GEM was recycled 10 times, indicating that PSL/Fe₃O₄@GEM had very good reusability. In addition, the transesterification resolution of (R,S)‐1‐(4‐methylphenyl)‐2‐propen‐1‐ol and (R,S)‐1‐(4‐bromophenyl)‐2‐propen‐1‐ol was catalyzed by PSL/Fe₃O₄@GEM, affording ideal ee_s and ee_p values of 99.3%, 97.4% and 99.6%, 98.2%, respectively. Therefore, PSL/Fe₃O₄@GEM demonstrated its potential as a highly efficient enzymatic reactor and Fe₃O₄@GEM would be very promising carriers for immobilizing enzymes in industrial application.     

TiO2掺杂调控聚苯乙烯微球折射率及胶体光子晶体结构色

胶体光子晶体由于其可调变的结构色在绿色印刷、印染等领域备受关注,而其光子带隙的宽度和位置由光子晶体的晶格参数(晶面间距,通常受胶体微球尺寸影响)和介质的折射率决定。现有人工胶体光子晶体主要基于SiO_2和高分子(如聚苯乙烯(PS)等)微球的组装制备,由于胶体微球材质种类有限,折射率调控受限,因而目前调控胶体光子晶体结构色主要靠改变胶体微球的尺寸来实现。本文首先制备高折射率(2.6)的TiO_2纳米晶,在乳液聚合制备单分散的PS(折射率1.6)微球过程中,将所制备的TiO_2纳米晶掺杂于PS微球中,通过TiO_2的掺杂量有效调控胶体微球的折射率,进而实现胶体光子晶体的结构色调控。以多色胶体光子晶体微球的水溶液为墨水,采用彩色喷墨打印技术打印了电脑设计的光子晶体彩画。本文发展的光子晶体结构色调控新技术拓展了胶体光子晶体的应用。