Synthesis and Characterization of Dendrimer‐Encapsulated Bimetallic Core‐Shell PdPt Nanoparticles

Using a successive method, PAMAM dendrimer‐encapsulated bimetallic PdPt nanoparticles have been successfully prepared with core‐shell structures (Pd@Pt DENs). Evidenced by UV‐vis spectra, high resolution transmission electron microscopy, and X‐ray energy dispersive spectroscopy (EDS), the obtained Pd@Pt DENs are monodispersed and located inside the cavity of dendrimers, and they show a different structure from monometallic Pt or Pd and alloy PdPt DENs. The core‐shell structure of Pd@Pt DENs is further confirmed by infrared measurements with carbon monoxide (IR‐CO) probe. In order to prepare Pd@Pt DENs, a required Pd/Pt ratio of 1:2 is determined for the Pt shell to cover the Pd core completely. Finally, a mechanism for the formation of Pd@Pt DENs is proposed.     

单分散金属介电复合粒子制备及表征研究

过去20年纳米材料科学与技术的飞速发展使人们对于这种新材料寄予极大的期望,合成、组装及设计纳米相材料取得了巨大的进步。一方面单纯的纳米线、纳米杆、纳米晶、纳米管、纳米带、纳米球及量子点材料不断的被报道;另一方面,人们也加大了寻找纳米复合材料的步伐。以二氧化硅等胶体球形粒子为基体发展起来的纳米包覆(nanocoating)技术引起人们的极大兴趣犤1犦。这种纳米包覆技术得到的产物常常被称为核壳粒子(core-shellparticles),通常包括作为核的基体球的表面性质改性与其它材料于表面包覆形成壳层。纳米包覆技术实际上也是粒子表面性质…     

Silver Hollow Microspheres: Large-scale Synthesis, Characterization and Electromagnetic Shielding Property

A facile and large-scale synthesis method to fabricate silver hollow microspheres with controllable morphologies and shell thickness is described using low-cost glass microspheres as templates. The method mainly involves two steps of the preparation of silver-coated glass microsphere core-shell particles by a controllable liquid reduced reaction of Ag[(NH3)2]+ solution, which only produces silver nanoparticles anchored on the surface of the thiolated glass microsphere templates, and the removal of glass microspheres by wet chemical etching with HF solution. The products are well characterized by field emitted scanning electron microscopy (SEM), transmitted electron microscopy (TEM), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) etc. The as-prepared core-shell particles and hollow particles have even and compact silver shells. The electromagnetic shielding coatings based on the silver hollow microspheres are demonstrated to have high conductivity, excellent shielding effectiveness and long durability, suggesting that the silver hollow microspheres obtained here are a novel light-weight electromagnetic shielding filler and will have extensive applications in the electromagnetic compatibility fields.     

聚合物微球的自组装与微图形材料

苯乙烯;丙烯酸;共聚物;聚合物微球的自组装与微图形材料     

一步法制备PNIPAAm-g-PAN/PSt载银复合微球及其抗菌性能研究

以AgNO3为金属源,通过乙醇将与聚N-异丙基丙烯酰胺接枝聚丙烯腈/聚苯乙烯（PNIPAAm-g-PAN/PSt）聚合物微球表面酰胺基团配位的银离子（Ag+）还原,一步法制备了PNIPAAm-g-PAN/PSt载银复合微球。通过傅立叶变换红外（FTIR）和紫外-可见光光谱表征发现,由Ag+还原所得的Ag纳米颗粒被成功地固载在PNIPAAm-g-PAN/PSt 微球上;用透射电子显微镜（TEM）对载银微球的大小和形态进行了表征;热重分析（TGA）结果表明,固载在微球表面的银纳米颗粒的含量（质量分数）为12%;抗菌实验结果表明,所制备的载银微球具有抗革兰氏阴性菌的活性。     

Synthesis of PEDOT Nanoparticles and Vesicles by Dispersion Polymerization in Alcoholic Media

Summary: The synthesis of PEDOT nanoparticles and vesicles by dispersion polymerization in a methanol/water mixture (3/2, v/v) is reported, using either ammonium persulfate or iron(III) p‐toluenesulfonate as oxidants and α‐EDOT‐PEO as a reactive stabilizer. The influence of the oxidant as well as the α‐EDOT‐PEO molar mass and concentration on the core‐shell particle morphology and conductivity properties have been investigated. PEDOT particles with conductivities up to 1.5 × 10⁻² S · cm⁻¹ have been obtained in high yield.

TEM image of PEDOT vesicles prepared using PEO‐based stabilizers of 25 000 g · mol⁻¹ in water/methanol mixture (2:3 v/v) at room temperature using ammonium persulfate as an oxidant.     

单分散亚微米级磁性微球的合成

以磁性氧化铁胶体粒子为种子粒子，采用吸附－溶胀法，进行苯乙烯－丙烯酸－二乙烯基苯的乳液聚合，制备亚微米级磁性高分了微球。研究了分散介质、丙烯酸、种子粒子、苯乙烯和ＰＨ调节剂等因素对聚合行为和磁性微球的影响，成功地合成了平均粒径为０．１３和０．２７μｍ、单分散性很好的磁性微球。     

Synthesis of poly[(2‐oxo‐1,3‐dioxolane‐ 4‐yl)methyl methacrylate‐co‐styrene] by addition reaction of carbon dioxide and its compatibility with poly(methyl methacrylate) or poly(vinyl chloride)

We investigated the chemical fixation of carbon dioxide (CO ₂) to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer to polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl)methyl methacrylate‐co‐styrene] [poly(DOMA‐co‐St)] from the addition of CO ₂ to poly(glycidyl methacrylate‐co‐styrene) [poly(GMA‐co‐St)], quaternary ammonium salts showed good catalytic activity at mild reaction conditions. The CO ₂ addition reaction followed pseudo first‐order kinetics with the concentration of poly(GMA‐co‐St). In order to expand the applications of the CO ₂ fixed copolymer, polymer blends of this copolymer with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) were cast from N,N′‐dimethylformamide (DMF) solution. Miscibility of blends of poly(DOMA‐co‐St) with PMMA or PVC have been investigated both by differential scanning calorimetry (DSC) and visual inspection of the blends, and the blends were miscible over the whole composition ranges. The miscibility behaviors were also discussed in terms of FT‐IR spectra. Copyright © 2002 John Wiley & Sons, Ltd.     

N掺杂空心TiO2微球的合成与表征

采用无皂乳液聚合合成的聚苯乙烯(PS)微球为模板、氨水/三乙醇胺为催化体系, 通过溶胶-凝胶方法合成了PS/TiO₂(核/壳)复合微球, 然后通过煅烧制备了N掺杂、锐钛型空心TiO₂微球. 在反应体系中三乙醇胺扮演双重角色, 既是TiO₂生成及包覆过程的抑制剂又是空心TiO₂微球的N掺杂剂. 改变氨水、三乙醇胺和钛酸正丁酯用量可控制TiO₂壳的形态和尺寸. 氨水用量增加, PS/TiO₂复合微球的壳表面变得粗糙|三乙醇胺用量增加, 壳表面变得光滑|钛酸正丁酯用量提高导致壳层变厚. 改变三乙醇胺用量可调节空心TiO₂微球中的N掺杂量|N掺杂空心TiO₂微球具有可见光响应和光催化作用.     

单分散掺硫碳微球的水热制备及其表征

以可溶性淀粉为碳源,采用硫辅助水热碳化法一步制备了平均粒径约为4 μm的单分散掺硫碳微球。利用扫描电镜、透射电镜、X射线衍射、氮气吸脱附、傅里叶变换红外光谱、X射线光电子能谱、固体核磁共振等手段对掺硫碳微球的结构和性质进行了表征。硫辅助水热碳化法可以在高浓度条件下高产量地制备分散性良好的掺硫碳微球,更重要的是硫原子可以同步进入碳的网络结构中。与传统水热碳化法相比,采用硫辅助水热碳化法制备的掺硫碳微球具有更高的比表面积,其可能的原因是硫原子的引入产生了大量的化学与结构缺陷:-S-S-、-S-、-SO₂-和-SO-等基团构成化学缺陷,而噻吩等五元环取代石墨六元环形成结构缺陷。     

接枝共聚法制备二氧化钛/聚（苯乙烯-二乙烯基苯）复合微球

本文以KH560、苯乙烯、马来酸酐为连接组分,将二氧化钛接枝到聚（苯乙烯-二乙烯基苯）微球的表面,成功制备了无孔和多孔纳米复合微球。研究了硅烷偶联剂（KH560）和苯乙烯对二氧化钛在无孔微球表面的分散性和接枝数量以及支撑微球的多孔性质对接枝到微球内部的二氧化钛数量的影响。结果表明,KH560和苯乙烯能够提高二氧化钛在微球表面的分散性和稳定性,使二氧化钛以30-80nm的粒径接枝在微球表面。苯乙烯又能使二氧化钛在无孔微球表面的接枝数量从10.4%增大到20.4%。平均孔径为136nm的多孔微球为支撑微球得到的复合粒子中二氧化钛最高接枝量可达26%,明显高于无孔微球和平均孔径为31nm的多孔微球。     

单分散掺硫碳微球的水热制备及其表征

以可溶性淀粉为碳源,采用硫辅助水热碳化法一步制备了平均粒径约为4μm的单分散掺硫碳微球。利用扫描电镜、透射电镜、X射线衍射、氮气吸脱附、傅里叶变换红外光谱、X射线光电子能谱、固体核磁共振等手段对掺硫碳微球的结构和性质进行了表征。硫辅助水热碳化法可以在高浓度条件下高产量地制备分散性良好的掺硫碳微球,更重要的是硫原子可以同步进入碳的网络结构中。与传统水热碳化法相比,采用硫辅助水热碳化法制备的掺硫碳微球具有更高的比表面积,其可能的原因是硫原子的引入产生了大量的化学与结构缺陷:-S-S-、-S-、-SO2-和-SO-等基团构成化学缺陷,而噻吩等五元环取代石墨六元环形成结构缺陷。     

Poly(ethylene terephthalate) copolymers containing 5‐nitroisophthalic units. I. Synthesis and characterization

Poly(ethylene terephthalate‐co‐5‐nitroisophthalate) copolymers, abbreviated as PETNI, were synthesized via a two‐step melt copolycondensation of bis(2‐hydroxyethyl) terephthalate and bis(2‐hydroxyethyl) 5‐nitroisophthalate mixtures with molar ratios of these two comonomers varying from 95/5 to 50/50. Polymerization reactions were carried out at temperatures between 200 and 270 °C in the presence of tetrabutyl titanate as a catalyst. The copolyesters were characterized by solution viscosity, GPC, FTIR, and NMR spectroscopy. They were found to be random copolymers and to have a comonomer composition in accordance with that used in the corresponding feed. The copolyesters became less crystalline and showed a steady decay in the melting temperature as the content in 5‐nitroisophthalic units increased. They all showed glass‐transition temperatures superior to that of PET with the maximum value at 85 °C being observed for the 50/50 composition. PETNI copolyesters appeared stable up to 300 °C and thermal degradation was found to occur in two well‐differentiated steps. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1934–1942, 2000     

醇热法合成单晶银纳米线及其表征

以硝酸银为前驱物, 聚乙烯醇缩丁醛(PVB)为结构导向剂, 通过醇热法, 反应温度为140 ℃, 反应时间为24 h的条件下制备了银纳米线. 采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、热重分析(TG)、红外光谱(FT-IR)和激光拉曼光谱(Raman)等手段对产物进行了系统表征, 结果表明: 所得银纳米线具有面心立方结构, 沿着(111)晶面生长, 具有单晶结构; 考察了反应温度和时间对产物形貌的影响, 结果表明: 反应温度和时间在形成银纳米线的过程中起着关键的作用; 银纳米线具有较强的表面增强拉曼散射效应; 同时提出了银纳米线可能的晶化机理.     

Monodispers and Multifunctional Magnetic Composite Core Shell Microspheres for Demulsification Applications

Iron oxide@Poly(Glycidylmethacrylate‐methyl methacrylate‐divinyl benzene) magnetic composite core shell microspheres Fe₃O₄@P(GMA‐MMA‐DVB) with epoxy group on the surface was designed and synthesized by solvothermal process followed by distillation polymerization. The surface epoxy group was modified with amino group of ethylene diamine (EDA) to prepare Fe₃O₄@P(GMA‐MMA‐DVB)/NH₂ microspheres, and then effects of modification on the structure, interfacial behavior and hence demulsification of the amino modified epoxy coating were examined. The prepared magnetic microspheres were characterized using a laser particle size analyzer, transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and thermogravimetric analysis. Fourier transform infrared spectrometer analysis indicates the presence of epoxy group, amino group and Fe₃O₄ in the final Fe₃O₄@P(GMA‐MMA‐DVB) and Fe₃O₄@P(GMA‐MMA‐DVB)/NH₂ magnetic core shell microspheres. Our experimental results show that Fe₃O₄@P(GMA‐MMA‐DVB)/NH₂ magnetic core shell microspheres exhibit good interfacial and demulsification properties and able to remove emulsified water from stable emulsion. The resulting microspheres showed excellent magnetic properties and further these can be recycled and reused by magnetic separation.     

纳米CdS/TAB的组装合成及表征

合成了纳米CdS/TAB（双十八烷基双甲基溴化铵）的复合物，通过IR，UV－Vis,XRD,TEM,AFM和SPS的研究，证实了CdS纳米晶的存在和核－壳结构的形成，并且证实了通过改变反应物的配比可以控制复合物的大小。EFM研究表明，这种有序的核－壳组装体可以产生电场超晶格。     

Core‐Shell Structured Monodisperse Poly(3,4‐Ethylenedioxythiophene)/Poly(Styrenesulfonic Acid) Coated Polystyrene Microspheres and Their Electrorheological Response

We report the successful synthesis of transparent thin film of conducting poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS) coated monodisperse polystyrene (PS) microspheres via a simple physical adsorption route in an aqueous media and their electrorheological (ER) application under an applied electric field. Due to the insulating PS core, the PEDOT/PSS wrapped PS (PEDOT/PSS/PS) particles possess a low volume conductivity appropriately applied as ER active materials. Tested by a rotational rheometer under an applied electric field, the PEDOT/PSS/PS based ER fluid dispersed in a silicone oil shows a typical Bingham‐fluid behavior with increased yield stresses according to the increase of electric field strength.

     

Poly(ethylene terephthalate) copolymers containing nitroterephthalic units. I. Synthesis and characterization

The synthesis, microstructure, and thermal behavior of a series of poly(ethylene terephthalate) (PET) copolymers containing nitroterephthalic units are described. These novel copolyesters were synthesized by transesterification followed by melt copolycondensation of dimethyl terephthalate and dimethyl nitroterephthalate mixtures with ethylene glycol. The molar ratio of the two comonomers in the feed varied from 95/5 to 25/75. Furthermore, PET and poly(ethylene nitroterephthalate) homopolymers were synthesized with the same method and comparatively studied. Copolyester compositions were practically the same as in the feed, and weight‐average molecular weights ranged from 10,000 to 60,000. The two monomeric units were randomly distributed along the polymer chain, and the experimentally determined average sequence lengths were in accordance with ideal copolycondensation statistics. Melting temperatures and enthalpies of the copolyesters decreased with increasing content in nitroterephthalic units, and they all showed a single glass‐transition temperature superior to that of PET. They appeared to be stable up to 300 °C, and thermal degradation occurred in two well‐differentiated steps. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3761–3770, 2000     

无皂乳液聚合制备单分散核-壳聚丙烯酸微粒

核壳微粒;丙烯酸聚合物;无皂乳液聚合制备单分散核-壳聚丙烯酸微粒