Fabrication Of Composite Particles Research Articles

Синтез композитных частиц феррит кобальта/пьезоэлектрик для использования в качестве магнитоэлектрических элементов в костных имплантатах

Bone implants capable to create an electrical stimulus for bone tissue regeneration under the influence of an external magnetic field are considered. A promising method for generating local electric fields is the use of magnetoelectric (multiferroic) micro- and nanoparticles, being polarized under the action of an external magnetic field, creating electric fields comparable in amplitude to endogenous ones. Of practical interest are composite magnetoelectric particles consisting of a ferrimagnetic core and a piezoelectric shell brought into close mechanical contact. The paper presents the results of modeling the magnetoelectric effect in a composite particle, fabrication of composite particles with cobalt ferrite as a magnetostrictive core, and considers the issues of the chemical interaction of phases.

Fabrication of composite particles through single pass using a coaxial tube reactor

Composite particles were prepared by liquid–liquid interfacial crystallization in a coaxial tubular reactor. A microfluidic channel was utilized for controlling particle properties and fabricating composite particles via a single pass in a continuous flow process. Changes in flow patterns with Weber number were investigated by visualizing flow patterns in the reactor; four types of flow patterns were observed. Particle size distributions of sodium chloride (NaCl) in the reactor were optimized by controlling flow patterns. Crystal nucleation rates and growth rates were calculated using the Rosin–Rammler distribution, which is also used in conventional crystallizers. Indomethacin (IMC) crystals with a fibrous morphology were obtained in any of three flow patterns by ultrasonic irradiation of the tube reactor; however, precipitation of IMC did not occur without ultrasonic irradiation. Composite particles of NaCl and IMC were produced by ultrasonic irradiation in a dispersed flow. The process involving dispersed flow could be used to continuously fabricate composite particles in a single pass through the reactor.

Fabrication of composite particles by liquid–liquid interfacial crystallization using an ultrasonic spray nozzle

The purpose of this study was to produce composite particles, consisting of core starch particles coated with glycine, by liquid–liquid interfacial crystallization with an ultrasonic spray nozzle and to investigate the effect of operating conditions on glycine particle morphology. We confirmed that ultrasonic irradiation could improve the coating efficiency of the core starch particles during the crystallization process. We also investigated the transformation between different polymorphs of glycine crystals that covered the starch surface. The coating efficiency of the fine glycine crystals on the starch particles was improved by using an ultrasonic spray nozzle rather than anti-solvent crystallization without an ultrasonic spray nozzle. The glycine crystals on the surface of starch particles transformed from unstable to stable forms according to the solution-mediated mechanism and Ostwald rule of stages. The interaction between the core particles and guest particles was found to be a key factor in producing the composite particles. The results indicate that this crystallization process using the ultrasonic spray nozzle is promising for efficiently producing composite particles.

Fabrication of composite particles by attaching surface-modified nanoparticles to core particles by wet processing in organic solvents

A simple wet processing route for the formation of composite particles via the adsorption of highly dispersible nanoparticles onto the core particles in organic solvents, without the formation of strong aggregates, was developed. The process involved a simple mixing procedure using core particles and surface-modified highly dispersible nanoparticles (shell nanoparticles) in organic solvents, assisted by ultrasonication. As a model study, submicron-sized (ca. 400nm) and nano-sized (ca. 30nm) SiO2 particles, prepared by Stöber process, were applied as the core and shell materials, respectively. The surface of the shell SiO2 nanoparticles was modified by a layer-by-layer process that involves the adsorption of cationic polyethyleneimine and an anionic surfactant comprising branched alkyl and polyethylene glycol chains for improving the stability in various organic solvents, as well as for controlling the interaction with the core material. The surface modified shell SiO2 nanoparticles were found to be effectively adsorbed onto the core SiO2 particles when mixed in toluene, while minimal adsorption was observed in ethanol. The obtained composite particles showed improved stability compared to raw core SiO2 particles in toluene. The adsorption mechanism of the shell SiO2 nanoparticles on the core particles in various organic solvents was proposed on the basis of surface-interaction measurements by atomic force microscopy colloidal probe methods. We believe that a long-range adhesive force between the shell SiO2 nanoparticles and the core particles played an important role in promoting effective adsorption, allowing the formation of composite particles.

A Facile Synthesis of Silver-Coated Composite Particles bySwelling Surface Method

We report a facile and rapid method for fabrication ofcomposite particles consisting of a polystyrene (PS) core anda uniform silver shell. The process involves the PS colloidsurface swelling, the anchoring of silver ions and nanoparticles ontothe surfaces, and the subsequent growth of metal seeds in a shortperiod. The present approach has the advantages of simplicity and highefficiency. The TEM images show the morphology of the obtained PScore-silver shell particles, and their chemical composition andcrystallinity are analysed by x-ray diffraction. To our knowledge, thisis the first study based on swelling PS surface for synthesis ofsilver-coated PS particles and may be implemented for preparingother metal-coated PS particles.

Fabrication of composite particles with core-shell structures by a novel processing

In order to solve the difficult problem of heterogeneity of different components in the procedure of ceramic preparation, novel processing (heterogeneous nucleation-and-growth processing) was used to prepare a homogeneous distribution of powders. Composite coated particles with core-shell structures were prepared by the heterogeneous nucleation-and-growth processing. The effects of silica content in composite coating particles versus concentration of tetraethylorthosilicate, pH value, reaction time and reaction temperature were studied. The amorphous silica shell on the cores was confirmed by X-ray diffraction, transmission electron microscopy and zeta potential measurement.