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Magnetite (Fe304)/polyaniline core–shell composites were synthesized using a reactive surfactant to
improve magnetite dispersion and as the monomer of conducting polyaniline. Reduction of magnetic particle
aggregation and core-shell morphology were evidenced by electron microscopy. Additionally, the decrement in
magnetization (r) and (hysteresis) Hc observed in the core–shell composite was be attributed to the increment in
dipolar magnetic interaction due to the increased separation among the Fe3O4 nanoparticles because of the PAni
Powder mixture of magnetite (Fe3O4) and elemental zinc (Zn) was high energy ball milled looking forward to synthesize a composite material able to enhance magnetic coercivity (Hc). Results revealed up to 449.1 Oe for powder mixture treated for 540 min milling. Specific saturation magnetization (σs) of 50.35 and 43.7 emu/g was respectively reached in samples ball milled for 300 and 540 min. Moreover, specific remanent magnetization (σr) of 3.976 and 9.507 emu/g was respectively obtained for samples ball milled for 60 and 540 min. It is speculated that the degree of magnetization developed on studied samples might be influenced from the metallic-contamination derived from milling wear media such as Fe, Cr and Ni (stainless steel). The Zn–ferrite powder mixture processing and its preliminary magnetization results are discussed.
trabajo de investigación de Red Temática
A conducting-electroactive polyaniline/magnetite (PAni/Fe304) nanocomposite was synthesized using anilinium dodecylbenzene sulfonate (S1) as a reactive surfactant. First, S1 allowed magnetite dispersion in the aqueous phase and second, S1 performed as the monomer of polyaniline emeraldine base salt. Electron microscopy suggested core-shell morphology based on S1 amphiphilic character; that is, S1 adsorbed onto the magnetite nanoparticles surface and then was polymerized via an oxidative polymerization forming the shell. The PAni/Fe304 composite exhibited improved thermal stability regarding pure PAni, which was related to the strong interaction between PAni and magnetite. Electrical conductivity, determined by the four-probe method, was in the order of 10-1 and 10-3 S cm-1, respectively, for the pure PAni and the composite. Concerning composite magnetic properties, the decrement in magnetization (σr) and hysteresis (Hc) was attributed to the increment in dipolar magnetic interaction due to the increased separation among magnetite nanoparticles because of the PAni shell.
PROMEP-SEP, Programa: Redes Temáticas de Colaboración Académica, "Red de Compuestos Poliméricos, Propiedades y Aplicaciones
Acknowledgments The authors acknowledge the Kleberg Advanced Microscopy Center (KAMiC) and NIH RCMI Nanotechnology and Human Health Core (Grant 5G12RR013646-12) at University of Texas at San Antonio for the support with electron microscopy. The authors gratefully acknowledge Dr. Elizande-Galindo and Dr. Farias Mancilla from UACJ for their technical support with magnetic measurements. This research was funded by UAEM Grant 3688/20147CIB and CONACYT Grant 280518. The authors thank the Cátedras-CONACYT program and the Facultad de Odontología, Universidad Autónoma Benito Juárez de Oaxaca, for their support. The authors also thank the financial support from DGAPA-UNAM: PAPIIT-IA205518 and PAPIME-PE208518.
In this work, we present a simple and efficient method for pure phase magnetite (Fe3O4) nanoparticle synthesis. The phase structure, particle shape, and size of the samples were characterized by Raman spectroscopy (Rm), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDS), and transmission electron microscopy (TEM). The morphology tuning was controlled by the temperature of the reaction; the nanoparticles were synthesized via the hydrothermal method at 120°C, 140°C, and 160°C, respectively. The Rm and XRD spectra showed that all the nanoparticles were Fe3O4 in a pure magnetite phase. The obtained nanoparticles exhibited a high level of crystallinity with uniform morphology at each temperature, as can be observed through TEM and SEM. These magnetic nanoparticles exhibited good saturation magnetization and the resulting shapes were quasi-spheres, octahedrons, and cubes. The samples showed striking magnetic properties, which were examined by a vibrating sample magnetometer (VSM). It has been possible to obtain a good morphological control of nanostructured magnetite in a simple, economical, and scalable method by adjusting the temperature, without the modification of any other synthesis parameter.
JORGE TORRES RODRIGUEZ (2017)
Se llevó a cabo la síntesis de nanopartículas de magnetita (Fe3O4) y de cobalto zinc (Co0.25Zn0.75Fe2O4) por el método de coprecipitación química. Luego, estas nanopartículas fueron recubiertas con una coraza de sílice (SiO2), a través del método sol-gel. De esta forma se desarrollaron sistemas nanoestructurados núcleo-coraza de Fe3O4@SiO2 y Co0.25Zn0.75Fe2O4@SiO2 con tamaños menores a los 100 nm. Con estos materiales se realizó un procedimiento experimental para su aplicación en la extracción magnética de ácido desoxirribonucleico (ADN), evaluando los rendimientos de extracción mediante absorción de luz ultravioleta y electroforesis en gel. Las caracterizaciones de los materiales núcleo-coraza propuestos se realizaron mediante difracción de rayos X (XRD), microscopias electrónicas (SEM, TEM) y espectroscopias electrónicas (EDS, FTIR, XPS). Con este trabajo se demostró que los sistemas propuestos son potenciales candidatos para la fabricación industrial de sistemas para la extracción magnética de ácidos nucleicos.
It was carried out the synthesis of nanoparticles of magnetite (Fe3O4) and cobalt zinc ferrite (Co0.25Zn0.75Fe2O4) by a chemical coprecipitation method. Later, these particles where covered with a Shell of silica (SiO2), via sol-gel method. With this process, nanostructure systems of core-shell Fe3O4@SiO2 and cobalt zinc ferrite Co0.25Zn0.75Fe2O4@SiO2 with smaller sizes than 100 nm, were developed. An experimental process for a magnetic extraction of deoxyribonucleic acids application was carried out with these materials, evaluating the extraction yields by ultraviolet light absorption and gel electrophoresis. The characterization of these core-shell materials were performed under X-ray diffraction (XRD), electronic microscopies (SEM, TEM) and electronic spectroscopies (EDS, FTIR, XPS). With this work it was demonstrated that the proposed systems are potential candidates for industrial fabrication of nucleic acids magnetic extraction systems.
Nanopartículas núcleo-coraza; extracción magnética de ácidos nucleicos; magnetita Core-shell nanoparticles; magnetic nucleic acid extraction; magnetite; cobalt zinc ferrite INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA DE MATERIALES PROPIEDADES DE LOS MATERIALES