A facile route to hollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via inverse miniemulsion polymerization

In this article, we report a facile route to the preparation of hollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via inverse miniemulsion polymerization at room temperature and under ambient pressure. Water droplets act as a soft template for the formation of hollow structure. Meanwhile, the existence of amphipathic magnetite nanoparticles (MPs) which can assemble at the interface of W/O is favorable to the interfacial polymerization of styrene, ensuring the formation of hollow nanocomposite microspheres. The final products were thoroughly characterized by X‐ray powder diffraction (XRD), fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), field‐emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and X‐ray photoelectron spectroscopy (XPS), which showed the formation of hollow magnetite/polystyrene nanocomposite microspheres. Magnetic hysteresis loop measurements revealed that both MPs and hollow nanocomposite microspheres displayed superparamagnetism. The effects of the content of H₂O, sorbitan monooleate (Span 80) and styrene and the dose rate on the morphology of nanocomposite microspheres were studied. Furthermore, the mechanism of the formation of the hollow magnetic microspheres was also discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3900–3910, 2008     

Fabrication of novel multihollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via water-in-oil-in-water double emulsions

We herein present a novel and simple synthetic strategy for fabricating multihollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via water-in-oil-in-water double emulsions. Amphipathic magnetite nanoparticles surface-modified with oleic acid act as an oil-soluble emulsifier and sodium dodecyl sulfate acts as a water-soluble surfactant in the system. The final products were thoroughly characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy, which showed the formation of multihollow magnetite/polystyrene nanocomposite microspheres. Preliminary results of magnetic properties of multihollow magnetite/polystyrene microspheres were reported. The effect of the content of amphipathic magnetite nanoparticles on the morphology of nanocomposite microspheres was studied. Furthermore, the mechanism of formation of multihollow magnetic nanocomposite microspheres was also discussed.     

细乳液聚合法制备磁性复合微球及其表征

在制备超细Fe3O4 磁性粒子的基础上 ,以 3种低分子量聚合物Disperbyk 1 0 6、Disperbyk 1 0 8和Disperbyk 1 1 1为Fe3O4 微粒在单体相中的分散稳定剂 ,采用细乳液聚合法制备了平均粒径为 3 40nm的PS Fe3O4 磁性复合微球 .详细研究了分散剂种类对细乳液聚合制备磁性复合微球的影响 ,并采用XRD、TGA和TEM等手段对磁性复合微球的形态、结构及磁响应性等进行了表征 .实验结果证明分散剂的选择对磁性复合微球的成功制备起着至关重要的作用 ,兼具酸性和碱性功能基的分散剂Disperbyk 1 0 6具有更好的分散和稳定效果 .TEM结果表明 ,所制备的复合微球具有一些缺陷 ,而缺陷处往往是Fe3O4 磁性粒子聚集的地方     

Fabrication of superparamagnetic magnetite/poly(styrene-co-12-acryloxy-9-octadecenoic acid) nanocomposite microspheres with controllable structure

We herein report a novel and facile approach to the fabrication of the superparamagnetic magnetite/poly(styrene-co-12-acryloxy-9-octadecenoic acid) nanocomposite microspheres with controllable structure via γ-ray radiation induced inverse emulsion polymerization under room temperature and at ambient pressure. 12-Acryloxy-9-octadecenoic acid (AOA, containing part of sodium salts Na–AOA) as a surfactant can also copolymerize with the styrene. It is interesting that just by changing the added amount of styrene, the magnetic hollow spheres with different wall thickness and various sizes of core, up to the magnetic solid spheres, can be obtained. The final products were thoroughly characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron diffraction (TEM), field-emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA) which showed the formation of magnetite/poly(styrene-co-AOA) nanocomposite microspheres. Magnetic hysteresis loop measurements showed that the magnetic nanocomposite microspheres exhibited superparamagnetism, which should make them have potential applications in biotechnology and biomedicine. Furthermore, we also proposed a possible formation mechanism of these magnetic microspheres with different morphologies.     

Surfactant-free miniemulsion polymerization as a simple synthetic route to a successful encapsulation of magnetite nanoparticles

Due to the existing interest in new hybrid particles in the colloidal range based on both magnetic and polymeric materials for applications in biotechnological fields, this work is focused on the preparation of magnetic polymer nanoparticles (MPNPs) by a single-step miniemulsion process developed to achieve better control of the morphology of the magnetic nanocomposite particles. MPNPs are prepared by surfactant-free miniemulsion polymerization using styrene (St) as a monomer, hexadecane (HD) as a hydrophobe, and potassium persulfate (KPS) as an initiator in the presence of oleic acid (OA)-modified magnetite nanoparticles. The effect of the type of cross-linker used [divinylbenzene (DVB) and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP)] together with the effect of the amount of an aid stabilizer (dextran) on size, particle size distribution (PSD), and morphology of the hybrid nanoparticles synthesized is analyzed in detail. The mixture of different surface modifiers produces hybrid nanocolloids with various morphologies: from a typical core-shell composed by a magnetite core surrounded by a polymer shell to a homogeneously distributed morphology where the magnetite is uniformly distributed throughout the entire nanocomposite.     

Nanocomposite particles with core-shell morphology II. An investigation into the affecting parameters on preparation of Fe3O4-poly (butyl acrylate-styrene) particles via miniemulsion polymerization

The encapsulation of inorganic particles with polymers is desirable for many applications in order to improve the stability of the encapsulated products and disperse ability in different media. Colloidal particles with magnetic properties have become increasingly important both technologically and for fundamental studies. This is due to their tunable anisotropic. In the absence of an applied magnetic field, the particles have isotropic sphere dispersion, whereas in an external magnetic field the particles form anisotropic structures. Here, latexes containing nanocomposite particles of styrene-butyl acrylate/Fe₃O₄ with core-shell structure were prepared through miniemulsion polymerization technique. Magnetic composite nanospheres with high magnetic content were synthesized through miniemulsion polymerization using a new process based on a three-steps preparation route including two miniemulsion processes: (1) preparing a dispersion of oleic acid coated magnetite particles in water; (2) mixing of modified magnetite particles with styrene/butyl acrylate in the presence of sodium dodecyl sulfate (SDS), sorbitane mono oleate (Span 80), hexadecane (HD) and (3) miniemulsification of the modified Fe₃O₄ into the monomer droplets to reach to complete encapsulation. Subsequent polymerization generated magnetic nanocomposite spheres. Hence, the copolymerization reaction was performed on the surface of such particles in order to obtain core-shell morphology for these nanoparticles, which were characterized by several techniques such as TEM, SEM, DLS, TGA, VSM and FT-IR. The magnetic copolymer particles with diameter of 120-170 nm were obtained. The effect of several parameters such as magnetite, surfactants and hydrophobe amounts on the stability, particle size and magnetization were investigated and also optimized.     

Anionic surfactant for silica-coated polystyrene composite microspheres prepared with miniemulsion polymerization

Raspberry-like composite microspheres with polystyrene (PS) cores and silica shell were prepared through miniemulsion polymerization by using the anionic sodium dodecyl sulfate (SDS) as a surfactant and 1-vinylimidazole (1-VID) as an auxiliary monomer. The strong acid–base interaction between acidic hydroxyl groups of silica surfaces and basic amino groups of 1-VID promote the formation of long-term stable PS/SiO₂ nanocomposite microspheres. Transmission electron microscopy TEM studies indicated that the acid–base interaction between silica nanoparticles and auxiliary monomer was strong enough for the formation of colloidally stable composite microspheres, which have raspberry-like morphology. Influences of several synthetic parameters, such as initial silica amount, the amount of auxiliary monomer 1-VID, and SDS concentration on the polymerization stability, diameters, and morphology of the composite microspheres were studied. A tentative mechanism of the formation of nanocomposite particles was proposed.     

Preparation and characterization of polymer/silica nanocomposites via double in situ miniemulsion polymerization

Polymer/SiO₂ nanocomposite microspheres were prepared by double in situ miniemulsion polymerization in the presence of methyl methacrylate, butyl acrylate, γ‐methacryloxy(propyl) trimethoxysilane, and tetraethoxysilane (TEOS). By taking full advantage of phase separation between the growing polymer particles and TEOS, inorganic/polymer microspheres were fabricated successfully in a one‐step process with the formation of SiO₂ particles and the polymerization of organic monomers taking place simultaneously. The morphology of nanocomposite microspheres and the microstructure, mechanical properties, thermal properties, and optical properties of the nanocomposite films were characterized and discussed. The results showed that hybrid microspheres had a raspberry‐like structure with silica nanoparticles on the shells of polymer. The silica particles of about 20 nm were highly dispersed within the nanocomposite films without aggregations. The transmittance of nanocomposite film was comparable to that of the copolymer film at around 70–80% from 400 to 800 nm. The mechanical properties and the fire‐retardant behavior of the polymer matrix were improved by the incorporation of silica nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3128–3134, 2010     

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.     

Covalent immobilization of albumin on micron‐sized magnetic poly(methyl methacrylate‐divinylbenzene‐glycidyl methacrylate) microspheres prepared by modified suspension polymerization

Micron‐sized magnetic poly(methyl methacrylate‐divinylbenzene‐glycidyl methacrylate) microspheres were prepared by a modified suspension polymerization in the presence of oleic acid‐coated magnetite nanoparticles. The magnetic microspheres were functionalized by reacting the epoxy groups with ammonia solution to provide amino groups. After activated with glutaraldehyde (GA), bovine serum albumin was covalently immobilized on these magnetic microspheres. The influence of initial protein concentration, pH and ionic strength of the protein solution on covalent immobilization was studied. Scanning electron micrographs showed that the magnetic microspheres had an average size of 6.4 µm and relative narrow size distribution. Magnetic measurement revealed the magnetic microspheres were superparamagetic with saturation magnetization of 7.32 emu/g. The successful amination of the magnetic microspheres was confirmed by Fourier transform infrared spectroscopy (FT‐IR). Copyright © 2005 John Wiley & Sons, Ltd.     

Preparation of magnetic polystyrene latex via the miniemulsion polymerization technique

Magnetic iron oxide (magnetite, Fe₃O₄) nanoparticles were encapsulated with polystyrene to give a stable water‐based magnetic polymer latex, using the miniemulsion polymerization technique. The resulting magnetic latexes were characterized with transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating sample magnetometer measurements (VSM), and ⁵⁷Fe Mössbauer spectroscopy measurements. TEM revealed that all magnetite nanoparticles were embedded in the polymer spheres, leaving no empty polystyrene particles. The distribution of magnetite particles within the polystyrene spheres was inhomogeneous, showing an uneven polar appearance. The DLS measurements indicated a bimodal size distribution for the particles in the latexes. According to our magnetometry and Mössbauer spectroscopy data, the encapsulated magnetite particles conserve their superparamagnetic feature when they are separated in the polymer matrix. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4802–4808, 2004     

具有核壳结构磁性复合微球的制备与表征

采用两步法制备了具有核壳结构的Fe3O4/P(MMA/DVB)(core)-P(St/GMA/DVB)(shell)磁性复合微球.首先,用改进的细乳液聚合制备了Fe3O4/P(MMA/DVB)微球;然后,加入总量不同的苯乙烯(St)、甲基丙烯酸缩水甘油酯(GMA)和二乙烯基苯(DVB),通过种子乳液聚合,制备了不同磁含量的核壳结构的磁性复合微球.分别用X-射线衍射(XRD)、高倍透射电镜(HR-TEM)、热重分析(TGA)、振动样品磁力计(VSM)等手段对磁性微球的性能进行了表征.实验结果表明,Fe3O4/P(MMA/DVB)微球的磁含量为84 wt%;通过改变加入壳层单体的量,核壳复合微球的磁含量可控在20 wt%~76 wt%之间.该微球具有超顺磁性,相应的饱和磁化强度为12~50Am2/kg.     

Photocatalytic and magnetic titanium dioxide/polystyrene/magnetite composite hybrid polymer particles

Novel multifunctional titanium dioxide (TiO₂)/polystyrene/magnetite composite hybrid polymer particle dispersions with TiO₂ nanoparticles in the surface and magnetite nanoparticles encapsulated inside the polymer matrix were produced by Pickering miniemulsion polymerization in one single step. Whereas TiO₂ nanoparticles were used to impart photocatalytic functionality and colloidal stability, magnetite nanoparticles were incorporated to allow an easy extraction for recovery and reuse of the composite multifunctional particles. The morphology of the composite particles was assessed by scanning transition electron microscopy (STEM) and energy‐dispersive X‐ray spectroscopy (EDX). The paramagnetism of the particles was analyzed using a SQUID magnetometer and their photocatalytic activity was assessed by degrading methylene blue (MB) solutions under UV light and by recovering and reusing of the particles in five consecutive cycles. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3350–3356     

Synthesis and properties of magnetite/poly (aniline‐co‐8‐amino‐2‐naphthalenesulfonic acid) (SPAN) nanocomposites

Composites were prepared by incorporating magnetite (Fe₃O₄) nanoparticles into the matrix of a sulfonated polyaniline (SPAN) [poly(aniline‐co‐8‐amino‐2‐naphthalenesulfonic acid) PANSA] through chemical oxidative polymerization of a mixture of aniline and 8‐amino‐2‐naphthalenesulfonic acid in the presence of magnetite nanoparticles. The composite, magnetite/SPAN(PANSA) was characterized by means of transmission electron microscopy (TEM), X‐ray diffraction (XRD), elemental analysis (EA), Fourier transform infrared (FT‐IR) spectra, UV‐vis spectroscopy, thermogravimetric analysis (TGA), conductivity and magnetic properties measurements. TEM image shows that magnetite nanoparticles were finely distributed into the SPAN matrix. XRD pattern of the nanocomposite reveals the presence of additional crystalline order through the appearance of a sharp peak at ～43° and 71°. Conductivity of the nanocomposite (0.23 S/cm) is much higher than pristine copolymer (1.97 × 10^?2 S/cm). The results of FT‐IR and UV‐visible spectroscopy reveal the presence of molecular level interactions between SO groups in SPAN and magnetite nanoparticles in the composite. Copyright © 2006 John Wiley & Sons, Ltd.     

Structure and electrochemical properties of magnetite and polypyrrole nanocomposites formed by pyrrole oxidation with magnetite nanoparticles

Nanocomposite of magnetic Fe₃O₄ nanoparticles and polypyrrole was prepared under sonication by a new chemical polymerization method during which Fe₃O₄ nanoparticles acted both as a pyrrole oxidant and as a component in the composite material. Synthesis of this nanocomposite was carried out in aqueous solution acidified to pH 2, a prerequisite for the formation of these types of material and to facilitate pyrrole oxidation by Fe₃O₄ nanoparticles. In this way, two kind of materials were produced: Fe₃O₄/PPy nanocomposite in which magnetite nanoparticles were dispersed in PPy matrix and Fe₃O₄-aggregates@PPy nanocomposite that exhibits structure in which aggregates of magnetite nanoparticles are surrounded by a layer of polymeric phase. In the latter case, the polymerization process took place in the presence of a surfactant. These nanocomposites were characterized by electron microscopy techniques, IR spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermogravimetry. Particular attention was focused on the study of the electrochemical properties of the formed composites. The composite of Fe₃O₄ and PPy exhibits reversible electrochemical behaviour upon oxidation. The electrode process of the polymeric component oxidation in organic solvents such as acetonitrile and dichloromethane is very similar to the process in an aqueous solution.

     

Novel preparation of magnetite/polystyrene composite particles via inverse emulsion polymerization

In this paper, super-paramagnetic magnetite/polystyrene (PSt) composite particles were prepared by inverse emulsion polymerization with water-based magnetic ferro-fluid as dispersing phase and organic solvent and styrene (St) as continuous phase. And the mechanism of the nucleation was discussed. The influence of factors, such as the monomer content, the amount of the ferro-fluid and the different continuous phases on the morphology of the magnetite/polystyrene composite particles was studied. The final products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Magnetic hysteresis loop measurements revealed that the composite particles were super-paramagnetic.     

Preparation of styrene polymer/ZnO nanocomposite latex via miniemulsion polymerization and its antibacterial property

Styrene polymer/ZnO nanocomposite latex was fabricated using miniemulsion polymerization in the presence of coupling agent 3-aminopropyltriethoxysilane (APTES) and hexadecane as hydrophobe. The size distribution and morphology of the composite latex particles were characterized by dynamic light scattering and transmission electron micrograph. X-ray photoelectron spectroscopy and Fourier transform infrared spectrophotometer results demonstrate that ZnO nanoparticles were encapsulated into polymer phases. The coupling treatment of ZnO with APTES can improve the dynamic contact angles of ZnO nanoparticle with water to enhance its hydrophobicity. When 0.6% APTES to ZnO (wt/wt) is used to modify ZnO, the encapsulation efficiency of ZnO reaches to 95%. It shows that the high encapsulation efficiency improves dispersion of ZnO nanoparticles in polymer film by scanning electron microscope. The stable structural hybrid latex can adequately exert unique function of nanoparticles in coatings. It indicates that the coatings added the composite latex exhibits perfect antibacterial activity, which has a tremendous potentiality in the field of coating materials.     

非离子乳化剂细乳液聚合制备草莓型PSt/SiO2纳米复合微球

通过细乳液聚合,使用非离子乳化体系辛基酚聚氧乙烯醚(CA-897),在纳米二氧化硅水分散介质中,以1-乙烯基咪唑(1-VID)作为辅助单体制备了苯乙烯为核,纳米二氧化硅为壳的草莓型PSt/SiO2有机-无机复合微球.实验范围内得到的复合微球的平均粒径和最终SiO2含量分别介于140～180 nm和19 wt%-31wt...     

Preparation of functionalized polystyrene latexes by radiation-induced miniemulsion polymerization using a Y-type polymerizable surfactant as sole stabilizers

Functionalized polystyrene latexes were prepared by miniemulsion polymerization using a Y-type polymerizable surfactant bearing a carboxylic acid group as sole stabilizers. Kinetics analysis showed that there was no constant rate stage, which coincided with the kinetics mechanism of the typical miniemulsion polymerization. The latexes obtained were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. It was found that the latexes prepared by miniemulsion polymerization initiated by gamma-ray had more narrowly particle size distribution compared with by potassium persulfate. XPS and FTIR results indicated that the carboxyl group was present on the surface of the polymer particles.     

Preparation of Surface-Imprinted Polymer Magnetic Nanoparticles with Miniemulsion Polymerization for Recognition of Salicylic Acid

Molecular surface-imprinted polymers nanoparticles encapsulating magnetite modified with oleic acid, for recognition of salicylic acid was prepared by three-step miniemulsion polymerization. The important factors including polymerization process, solvents, miniemulsifying approaches, and co-stabilizer have been investigated to obtain magnetic molecular imprinting polymers (MMIPs) nanoparticles (NPs) with high saturation magnetization (Ms), regular morphology, and good monodispersion. The results showed that the amount of magnetite encapsulated in MMIPs NPs was 43.4 wt% and Ms was 33.584 emu/g. Thus, MMIPs NPs could be separated easily within 2 minutes by an external magnetic field. The transmission electron microscope (TEM) showed MMIPs NPs were of regular sphere with core-shell structure, where magnetite NPs were uniformly encapsulated in homogeneous polymer shells. The average diameter of MMIPs NPs was 98 nm with RSD of 6.6%. Good recognition and high loading of target molecule were achieved by MMIPs NPs in batch rebinding tests.