Merrifield树脂负载咪唑基离子液体磁性微球的制备与表征

制备了Merrifield树脂负载丙酸甲酯基咪唑基离子液体磁性微球。 采用FT-IR和XRD对结构进行了表征,采用TGA和VSM分别进行了热稳定性和磁性测试。 结果表明,丙酸甲酯基咪唑基离子液体成功负载到Merrifield树脂微球上,并通过共沉淀的方法实现了微球的磁性化,其磁组分为FeOOH和γ-Fe2O3混合物。 磁性微球的热稳定性优于无磁性的Merrifield树脂负载丙酸甲酯基咪唑基离子液体微球,在200 ℃以下不发生分解。 磁性微球的磁化强度为11.364 emu/g,显示出超顺磁性,无外磁场存在时不发生团聚。 沉降实验结果表明,在磁感应强度为3.0×10-4 T电磁场作用下,磁性微球10 s内即可从水相中基本分离完全,而没有磁场作用时磁性微球粒子基本不从水相中分离。     

X-ray photoelectron spectroscopy as a tool for studies of the surface layer of microspheres. The case of polystyrene and poly(styrene–acrolein) microspheres with attached human serum albumin

The application of X-ray photoelectron spectroscopy (XPS) for studies of surface layers of objects with spherical shape was investigated using as examples polystyrene and poly(styrene–acrolein) microspheres with attached human serum albumin (HSA). The amounts of immobilized protein were determined by the standard biochemical Lowry method and by XPS, using the intensity of the N1s signals of HSA as a basis for evaluation. The XPS data were treated by taking into account the spherical shape of the particles analyzed (variable take-off angle of ejected electrons). The best agreement between the results of the biochemical and XPS determinations was found assuming that for the average particle the takeoff angle varies from 0° to 72.7°. This reflects the fact that in the multilayer arrangement of particles, placed onto the support of the XPS apparatus, the particles from the upper layer partially screen the edges of the particles in the layer below. Received: 23 November 1999 Accepted: 16 March 2000     

Preparation of styrene/methacrylic acid copolymer microspheres and their composites with metal particles

 Poly(styrene-co-methacrylic acid) [P(St-co-MAA)] microspheres were prepared by emulsifier-free emulsion copolymerization of St with MAA. Fourier transform IR spectroscopy and elemental analysis were used to study the change in the content of MAA in the microspheres. The results of X-ray photoelectron spectroscopy measurements indicated the presence of carboxylic functionality on the surface of the microspheres. The P(St-co-MAA) metal composite particles were prepared by chemical metal deposition. Transmission electron microscopy observation and X-ray diffraction measurement were used to study the distribution and structure of the metal particles deposited. Received: 15 September 1999 Accepted: 24 December 1999     

微米级单分散共聚物微球的制备

用分散聚合法制备了苯乙烯 甲基丙烯酸甲酯微米级单分散共聚物微球 ,粒径为 5 4 μm .将分散聚合体系与乳液聚合体系进行了比较 ,并对共聚物微球的形貌、粒径分布及共聚情况进行了表征研究 .     

Ceramic Micro-Particles Synthesised using Emulsion and Sol–Gel Technology: An Investigation into the Controlled Release of Encapsulants and the Tailoring of Micro-Particle Size

Controlled release technologies have many applications in such diverse fields as the pharmaceutical, agricultural, cosmetic and food industries, where tailored release rates and protection of the active molecule for delivery at a specific site or time are advantageous. Silica microspheres, with controlled diameters of 10–50 m and containing Orange II dye as a model encapsulant, have been synthesised by combining water-in-oil (w/o) emulsion technology with sol–gel chemistry. The average particle size may be controlled by the microemulsion parameters, including the surfactant and solvent concentrations, and by the sol–gel processing parameters, particularly water-to-silicon alkoxide ratio, pH, temperature, ageing and mixing conditions. Physical properties of the SiO₂ microspheres, which modulate the release rates of the encapsulated molecule (including pore size and tortuosity), are also controlled by the sol–gel process parameters.The effect of synthesis parameters, including surfactant concentration, sol–gel solution pH and drying temperature, on the morphology of the SiO₂ microspheres produced will be discussed. The effect of such parameters on the corresponding release rates of the model encapsulants will also be presented.     

亲/疏水不对称空心聚合物微球制备及磁性粒子装载研究

首先将(马来酸酐-醋酸乙烯酯共聚物)核/(马来酸酐-二乙烯基苯共聚物)壳微球的壳层外表面酐基烷基溴化,然后将核溶蚀、壳层内表面酐基水解,制得内表面含亲水羧基、外表面含烷基溴、具有微孔(Barrett-Joyner-Halenda平均孔径14.9nm)的空心聚合物微球.以此空心微球为微反应器,使Fe2+和Fe3+通过球壁...     

Preparation of monodisperse poly(St‐co‐PETEA) microspheres by precipitation polymerization using ethanol as solvent

Precipitation polymerization of styrene (St) was carried out with pentaerythritol tetraacrylate (PETEA) to produce monodisperse crosslinked microspheres. A much safer ethanol replaced acetonitrile as a solvent in precipitation polymerization of monodisperse crosslinked poly(St‐co‐PETEA) microspheres. Monodisperse crosslinked microspheres with high monomer conversion were achieved within 4 hr. Uniform and well‐separated monodisperse were obtained in ethanol when PETEA concentration varied from 30 vol% to 90 vol% and the particle diameter decreased from 0.75 to 0.58 µm. The particle yield increased from 36.51 to 64.38% by increase in the initiator loading from 1 to 8 wt%. No coagulum occurred between particles when the polymerization time varied from 2 to 10 hr. Copyright © 2010 John Wiley & Sons, Ltd.     

Novel potentiometric and optical silver ion-selective sensors with subnanomolar detection limits

Ten Ag⁺-selective ionophores have been characterized in terms of their potentiometric selectivities and complex formation constants in solvent polymeric membranes. The compounds with π-coordination show much weaker interactions than those with thioether or thiocarbamate groups as the coordinating sites. Long-term studies with the best ionophores show that the lower detection limit of the best Ag⁺ sensors can be maintained in the subnanomolar range for at least 1 month. The best ionophores have also been characterized in fluorescent microspheres. The so far best lower detection limits of 3 × 10⁻¹¹ M (potentiometrically) and 2 × 10⁻¹¹ M Ag⁺ (optically) are found with bridged thiacalixarenes.     

In situ biomimetic formation of nano‐hydroxyapatite crystals on chitosan microspheres

Chitosan (CS) is a biocompatible, noncytotoxic biomaterial used before as base material for composites. On the other hand, nano‐hydroxyapatite (nHA) is one of the main components of human bones, highly used for biomedical applications. In this work, CS microspheres were produced under a W/O emulsion system. CS microspheres with calcium ions were then exposed to Na₃PO₄ solution. In situ biomimetic nHA crystals were formed on CS microspheres to generate 15.14 ± 3.15‐μm composite microspheres. The microspheres were subsequently seeded with MG63 osteoblasts to observe their cell responses. All microspheres were characterized via scanning electron microscopy (SEM), phase‐contrast photomicroscopy, and X‐ray diffraction (XRD) analysis. The results showed flake‐like shape and islet‐like growth of nHA depositions presented on the surface of the CS microspheres. In vitro tests indicated that the CS/nHA microparticles were not only biocompatible but also enhanced cell adhesion and elongation due to the in situ biomimetic synthesis method.     

(Phen)2.5HPW/WO3复合空心微球的制备及光催化性能

通过磷钨酸H3PW12O40(HPW)和邻菲啰啉C12H8N2(Phen)的溶液反应,合成了杂多化合物(C12H8N2)2.5H3PW12O40((Phen)2.5HPW),以WO3空心微球为载体,负载杂多化合物(Phen)2.5HPW,制备了(Phen)2.5HPW/WO3复合空心微球.用等离子体原子发射光谱(ICP...