Resultant Composite Particles Research Articles

Fabrication of raspberry-like starch-based polymer microspheres for W/O and O/W emulsions separation and purification

Oil/water separation and purification is an important pursuit because of uncontrolled emissions of industrial effluent, which has a catastrophic impact on our aquatic environment and body health. Here, an amino-functionalized composite particles material was developed via Pickering polymerization and grafting of poly(ethylene imine) (PEI). The wettability of the resultant composite particles can be easily regulated via changing the dosage of PEI. At lower dosage of PEI, the composite particles exhibited underoil superhydrophobicity (UOWCA: 158.8°) which applied to separate W/O emulsions with high flux (∼ 170 L/m2 h). At higher dosage of PEI, it converted to underwater superoleophobicity (UWOCA: 158.1°) and could efficiently realize the separation of O/W emulsions with high flux (∼ 160 L/m2 h bar). And at specific dosage range of PEI, the resultant composite particles can separate W/O and O/W emulsions simultaneously under the joint action of rough structures, unique surface wettability and positive charge. In addition, the resultant amino-functionalized composite particles were positive charged which could effectively absorb many anionic water-soluble pollutants with high removal rate of almost 90 % during oil/water separation process. This research may provide a new idea for intelligent oil/water separation and purification in the future.

Synthesis and electrophoretic deposition of TiO2-SiO2 composite nanoparticles on stainless steel substrate

Titanium dioxide-silica composite nanoparticles were synthesized through a verified Stöber sol-gel method. The resultant nanoparticles, which consisted of titanium dioxide cores (35.54 ± 4.4 nm length rods) surrounded by ultrafine silica particles (3.22 ± 0.63 nm spheres) forming a thin shell, were electrophoretically deposited on an anodized stainless steel substrate to enhance its biological response in simulated body fluid (SBF). The presence of silica shell on TiO2 cores increased the surface roughness of the resultant composite particles and eliminated the cracks observed in the TiO2 coating due to the higher cohesion between the particles. The tape test results confirmed the higher adhesion of TiO2-SiO2 coating to the substrate. After 7 days of immersion in SBF solution, the silica shell resulted in a significantly higher Ca-P cluster formation on the TiO2-SiO2 coating compared to the TiO2 coating, which was almost free of Ca-P deposit. As the cracks were eliminated on the surface of the TiO2-SiO2 coating, the barrier performance of this coating was enhanced compared to the TiO2 coating in a phosphate-buffered saline solution.

Preparation of Fine-Drugs Layered Spherical Particles with Good Micromeritic and Dissolution Properties through Ultra Cryo-Milling and Mechanical Powder Processing.

The particles of phenytoin (Phe), a poorly water-soluble model drug, were bead-milled alone or co-milled with a hydrophilic waxy additive using an ultra cryo-milling technique in liquid nitrogen (LN2) to improve its dissolution properties. However, the micronized drug particles adhered and aggregated, resulting in poor handling in manufacturing processes such as blending or tableting. To improve the dissolution profile and powder properties of the drug simultaneously, the milled products were secondarily processed together with larger spherical particles by mechanical powder processing. These secondary products were composite particles with a core-shell structure, with fine drug particles adhered and deposited on the core, based on order mixing theory. As a core, three types/sizes of spherical pharmaceutical excipient particles were applied. The resultant composite particles produced much faster release profiles than just milled or co-milled mixtures. In addition, the composite particles showed good micromeritic properties depending on the size of the core particles. These results indicate that the ultra cryo-milling and subsequent dry composite mixing is a potential approach for developing drug particles with improved dissolution.

Well-Dispersed ZnFe2O4 Nanoparticles onto Graphene as Superior Anode Materials for Lithium Ion Batteries

We prepared well-dispersed ZnFe2O4 (ZFO) nanoparticles on a graphene sheet by a facile one-step hydrothermal method using glucose as a novel linker agent and low-cost graphene flake. It was found that the glucose linkage on graphene not only prevented the aggregation of ZFO particles, but also induced the exfoliation of graphene flakes. The addition of glucose during the synthesis made surface linkages on the graphene surface, and it reacted with ZFO precursors, resulting in the well-dispersed ZFO nanoparticles/graphene composite. Furthermore, the size distribution of the resultant composite particles was also shifted to the smaller particle size compared to the composite prepared without glucose. The newly prepared ZFO/graphene composite provided a higher lithium storage capability and cycle performance compared to the ZFO/graphene sample which was prepared without glucose. The good dispersion of ZFO nanoparticles on graphene and the small particle size of the composite led to markedly improved electrochemical performance. Its reversible discharge capacity was 766 mAh g−1 at 1 A g−1, and it also maintained as 469 mAh g−1 at 6 A g−1.

Facile and controllable synthesis of PS/AuNPs@PANi composite particles via Swelling–Diffusion–Interfacial-Polymerization Method

Herein, we reported a facile and controllable one-step process to fabricate micrometer-sized and monodisperse polystyrene/gold nanoparticles@polyaniline (PS/AuNPs@PANi) composite particles by means of the “Swelling–Diffusion–Interfacial-Polymerization Method” (SDIPM). Utilization of chloroauric acid as the oxidant for aniline monomer afforded the shell of the resultant composite particles simultaneously containing PANi and AuNPs. The PS/AuNPs@PANi composite particles were extensively characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetry. As a result, the synthesized PS/AuNPs@PANi composite particles show uniform size distribution and well-defined morphology, and furthermore, the structure and morphology of the AuNPs@PANi shell could be well controlled by simply changing the addition rate of chloroauric acid and weight ratio of aniline/PS. In addition, the mechanism governing the formation of PS/AuNPs@PANi composite particles was discussed.

Preparation and Surface Modification of Fe<sub>3</sub>O<sub>4</sub>@Sio<sub>2 </sub>Composite Microspheres

Magnetic Fe3O4@SiO2 composite microspheres were prepared using hydrolyzation of tetraethoxysilane and Fe3O4 nanoparticles as seeds, and then the resultant composite particles were modified with silane coupling agent 3-methacryloxypropyltrimethoxy silane. The products were characterized by scanning electron microscope, X-ray powder diffraction, fourier transform infrared spectroscopy, and vibrating-sanple magnetometry, respectively. The results clearly show that the magnetic particles have favorable superparamagnetism and remain strong magnetic response. Moreover, the duplex bonds of carbon functional groups from 3-methacryloxypropyltrimethoxy silane was introduced onto the suface of Fe3O4@SiO2 composite particles.

Preparation and Surface Modification of Fe<sub>3</sub>O<sub>4</sub>@Sio<sub>2 </sub>Composite Microspheres

Magnetic Fe3O4@SiO2 composite microspheres were prepared using hydrolyzation of tetraethoxysilane and Fe3O4 nanoparticles as seeds, and then the resultant composite particles were modified with silane coupling agent 3-methacryloxypropyltrimethoxy silane. The products were characterized by scanning electron microscope, X-ray powder diffraction, fourier transform infrared spectroscopy, and vibrating-sanple magnetometry, respectively. The results clearly show that the magnetic particles have favorable superparamagnetism and remain strong magnetic response. Moreover, the duplex bonds of carbon functional groups from 3-methacryloxypropyltrimethoxy silane was introduced onto the suface of Fe3O4@SiO2 composite particles.

Spray Freeze-Dried Porous Microparticles of a Poorly Water-Soluble Drug for Respiratory Delivery

Particles of poorly water-soluble drugs were prepared to develop a dry powder inhaler (DPI). Spray freeze-drying (SFD) technique using a four-fluid nozzle (4N), which has been developed by authors, was applied in this research. Ciclosporin and mannitol were used as a poorly water-soluble model drug and a dissolution-enhanced carrier, respectively. The organic solution of ciclosporin and aqueous solution of mannitol were separately and simultaneously atomized through the 4N, and the two solutions were collided with each other at the tip of the nozzle edge. The spray mists were immediately frozen in liquid nitrogen to form a suspension. Then, the iced droplets were freeze-dried to prepare the composite particles of the drug and carrier. tert-Butyl alcohol (t-BuOH) was used as the organic spray solvent due to its relatively high freezing point. The resultant composite particles with varying drug content were characterized depending on their morphological and physicochemical properties. The particles contained amorphous ciclosporin and δ-crystalline mannitol. The characteristic porous structure of SFD particles potentially contributed to their good aerodynamic performance. A series of particles with a similar size distribution and different drug content revealed that the incorporation of mannitol successfully improved the cohesive behavior of ciclosporin, leading to enhanced aerosol dispersion. The dissolution test method using low-volume medium was newly established to simulate the release process from particles deposited on the surface of the bronchus and pulmonary mucosa. The composite with hydrophilic mannitol dramatically improved the in vitro dissolution behavior of ciclosporin in combination with the porous structure of SFD particles.

Urchin-like Li4Ti5O12–carbon nanofiber composites for high rate performance anodes in Li-ion batteries

A facile strategy is developed based on a sol–gel method to prepare lithium titanate (Li4Ti5O12, LTO)–carbon nanofiber (CNF) composites as anode in Li-ion batteries (LIBs). Depending on the conductive CNF and carbon black (CB) additive contents added in the electrode, the resultant composite particles present either an urchin-like or a corn-dog structure with largely different electronic conductivities and associated electrochemical properties. When small amounts of both one-dimensional CNF and zero-dimensional CB particles, 5.0 wt% each, are present, conductive networks are established within the urchin-like LTO secondary particles by the penetrating multiple CNFs, whereas the CB particles attached onto the surface of the LTO particles connect the gaps between them, being able to form extensive three-dimensional conductive networks across the whole composites. The electrodes made from this composite deliver a remarkable capacity of 123 mA h g−1 when charged/discharged at 15 C, which is much higher than 91 mA h g−1 for those made from the neat LTO powders, a reflection of significant improvements in both the conductivity and Li ion diffusion coefficient in the composite electrode. When the CNF content is increased to 10 wt%, corn-dog shaped composites are formed consisting of individual CNFs penetrating the elongated LTO secondary particles along the axial direction with limited conductive networks. The electrodes made from this composite present much poorer capacities at all current rates than those with an urchin-like structure. These intriguing observations verify that both the structure of the active material and the conductivity of the electrode play important roles in delivering high capacities and rate capabilities.

Facile and Controlled Fabrication of Functional Gold Nanoparticle‐coated Polystyrene Composite Particle

Gold nanoparticles-coated polystyrene (AuNPs-coated PS) composite particles with raspberry-like morphology are successfully prepared with the aid of a unique thermodynamically driving effect. It is of considerable interest that the AuNPs generate and self-assemble with raw, ordinary PS microspheres that preexist in the oxidation-reduction systems. The synthesized AuNPs-coated PS composite particles have been extensively characterized using scanning electron microscope, transmission electron microscope, and UV-Vis-NIR spectroscopy. The results indicate that the morphology of the resultant composite particles is governed by simply changing the amount and type of reductants and the concentration of PS microspheres. The AuNPs-coated PS composite particles also exhibit the good surface-enhanced Raman scattering and catalytic performances.

Chemical vapor deposition of C on SiO 2 and subsequent carbothermal reduction for the synthesis of nanocrystalline SiC particles/whiskers

This study investigates chemical vapor deposition of C from CH 4 on particulate SiO 2 and subsequent carbothermal conversion of the resultant composite particles to SiC powders. Mass measurements, HR-TEM, SEM and XRD were used to characterize the products at various stages of the processes. It was found that oxide particles gained mass rapidly at 1300 K under CH 4 atmosphere owing to enhanced C uptake. Pyrolytic carbon layers 5–8 nm thick were deposited on SiO 2 particles. The coated powders with high C loadings (40–42.6 wt.% C) were converted to SiC under Ar flow in a temperature range of 1700–1800 K. Almost pure SiC powders containing a mixture of particles and whiskers of ~ 100 nm were synthesized at 1750 K for 45 min and at 1800 K for 30 min using the starting powder with 40 wt.% C. Whisker diameter increased with the C content of the coated powder. It was proposed that SiC whisker was grown by a vapor–solid mechanism. Equilibrium thermodynamic analysis by the method of minimization of Gibbs’ free energy predicted the reaction pathways to SiC and to the product species in the Si–O–C–Ar system. This study demonstrated that either C shell-SiO 2 core powders or SiC powders could be synthesized rapidly in the same reactor.

Structure and Photocatalytic Activity of Polythiophene/TiO2 Composite Particles Prepared by Photoinduced Polymerization

Polythiophene/titanium dioxide (PTh/TiO 2 ) composite particles were synthesized via the photoinduced polymerization of thiophene in a TiO 2 -chloroform suspension. The resultant composite particles were characterized by BET analysis, scanning electron microscopy, laser particle size analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The XPS spectra indicated that a strong interaction exists between the S sites of the polymer backbone and the TiO 2 particles. The UV-Vis DRS spectra showed that the resultant composite particles are responsive to visible light. The photocatalytic activities of the PTh/TiO 2 composite particles were examined through the degradation processes of a rhodamine B (RhB) solution under UV irradiation and visible light irradiation. The degradation ratios of the RhB solution were found to be 76% and 98% after UV irradiation (180 min) and visible light irradiation (10 h), respectively. The photocatalysis reactive mechanisms under UV irradiation and visible light irradiation were investigated using disodium ethylenediamine tetraacetate (EDTA-2Na, hole scavenger) and furfuryl alcohol (radical scavenger). The oxidant from the holes and the radicals are competitive. Under UV irradiation, photogenerated holes are the main active species while under visible light irradiation the radicals are the main oxidant for the degradation of RhB. ：通过光诱导噻吩在 TiO 2 的氯仿悬浮液中聚合反应, 制备了聚噻吩/二氧化钛 (PTh/TiO 2 ) 复合粒子, 并采用比表面积分析仪、扫描电子显微镜、粒径分析仪、X 射线光电子能谱、紫外-可见漫反射光谱和红外光谱对复合粒子进行了表征. 结果表明, PTh/TiO 2 复合粒子上的聚噻吩骨架中 S 原子与 TiO 2 粒子间存在强相互作用, 该复合粒子对可见光具有响应. 以罗丹明 B 为模型污染物, 研究了该复合粒子在紫外光和可见光照射下的光催化活性. 分别以乙二胺四乙酸二钠和呋喃甲醇为空穴捕捉剂和自由基捕捉剂研究了 PTh/TiO 2 复合粒子在紫外光和可见光照射下的光催化反应机理. 结果表明, 空穴和自由基是主要的光催化反应中的氧化性物质. 在紫外光照射下, 空穴起主要作用; 在可见光照射下, 自由基起主要作用. Polythiophene/titanium dioxide (PTh/TiO2) composite particles were synthesized via the photoinduced polymerization of thiophene. The photocatalytic reactivity of the composites under UV irradiation is better than that of TiO 2 . These composites can degrade rhodamine B under visible light irradiation.

Novel Spray Freeze-Drying Technique Using Four-Fluid Nozzle-Development of Organic Solvent System to Expand Its Application to Poorly Water Soluble Drugs

Spray freeze-drying (SFD) technique using four-fluid nozzle (4N), which is a novel particle design technique previously developed by authors, has been further developed to expand its application in pharmaceutical industry. The organic solvent was utilized as a spray solvent to dissolve the poorly soluble drug instead of conventional aqueous solution. Acetonitrile solution of the drug and aqueous solution of the polymeric carrier were separately and simultaneously atomized through 4N, and collided each other at the tip of nozzle edge. The spray mists were immediately frozen in the liquid nitrogen to form a suspension. Then, the iced droplets were freeze-dried to prepare the composite particles of the drug and carrier according to our proprietary method developed before. The resultant composite particles with phenytoin prepared by using acetonitrile (4N-SFD-MeCN system) were deeply characterized compared to those using aqueous solution (4N-SFD-aqua system) from morphological and physicochemical perspectives. The characteristic porous structure was observed in 4N-SFD-MeCN particles as well as 4N-SFD-aqua particles. However, it was found that the size and quantity of pore in 4N-SFD-MeCN particles were smaller than those of 4N-SFD-aqua particles. As a result, the former particles had 2- to 3-times smaller specific surface area than the latter particles independent of the type of carrier loaded. The slight difference of release profiles from the particles prepared between both systems was discussed from the microscopically structural viewpoint. In addition, ciclosporin was applied to organic solvent SFD system because this drug was poorly water soluble and cannot be applied to conventional aqueous SFD system. The release profiles from SFD particles were dramatically improved compared to the bulk material, suggesting that the new SFD technique using organic solvent has potential to develop the novel solubilized formulation for poorly water-soluble active pharmaceutical ingredients (APIs).

Lactose Composite Carriers for Respiratory Delivery

Lactose dry powder inhaler (DPI) carriers, constructed of smaller sub units (composite carriers), were evaluated to assess their potential for minimising drug-carrier adhesion, variability in drug-carrier forces and influence on drug aerosol performance from carrier-drug blends. Lactose carrier particles were prepared by fusing sub units of lactose (either 2, 6 or 10 microm) in saturated lactose slurry. The resultant composite particles, as well as supplied lactose, were sieve fractioned to obtain a 63-90 microm carriers. The carriers were evaluated in terms of size (laser diffraction) morphology (electron microscopy and atomic force microscopy), crystallinity and drug adhesion (colloid probe microscopy). In addition, blends containing drug and carrier were prepared and evaluated in terms of drug aerosol performance. The surface morphology and physico-chemical properties of the composite carriers were significantly different. Depending on the initial primary lactose size, the composite particles could be prepared with different surface roughness. Variation in composite roughness could be related to the change in drug adhesion (via modification in contact geometry) and thus drug aerosol performance from drug-lactose blends. Composite based carriers are a potential route to control drug-carrier adhesion forces and variability thus allowing more precise control of formulation performance.

シード粒子成長法による単分散シリカ微粒子への無機酸化物コーティング

Monodisperse silica seed particles were coated with silica, titania and iron oxide by a seed growth method that employs the hydrolysis and condensation of the metal alkoxides (tetraethoxysilan (TEOS), titanium tetraisopropoxide (TTIP) and iron tri-n-butoxide (TNBI)). The resultant composite particles kept the characteristics of monodisperse particles. Electroconductive particles were prepared by nitriding the titania-coated particles. The nitriding of the composite particles were carried out with ammonia gas in a tube furnace at various temperatures. The surface of titania-coated particles changed to titanium nitride at a temperature higher than 700°C, and the electroconductivity of the composite particles was high enough for the practical usage. Magnetic particles were also prepared by reducing the iron oxide coated silica particles with hydrogen gas at 500°C. The particles could be used as the model particles such as an EMR fluid although the magnetic property was relatively poor.

Composite Silica Particles Using a Mixture of Organosilane Monomers

Composite silica particles were synthesized by a two-step (acid-base) process in an aqueous solution with a mixture of organoalkoxysilane monomers. The two-step process separates the hydrolysis and condensation procedures to easily control condensation rate. In this study, the silane monomers used were phenyltrimethoxysilane (PTMS), vinyltrimethoxysilane (VTMS), methyltrimethoxysilane (MTMS), and tetraethyl-orthosilicate (TEOS). The physical properties of the resultant composite particles were investigated with the change in the molar ratio of monomers. The size of the particles increased with increasing the molar ratio of RaSi(OR)3/RbSi(OR)3 or RaSi(OR)3/TEOS (Ra: phenyl; Rb: vinyl, methyl).

Hydrate composite particles for ocean carbon sequestration: field verification.

This paper reports on the formation and dissolution of CO2/seawater/CO2 hydrate composite particles produced during field experiments in Monterey Bay, CA using a CO2 injector system previously developed in the laboratory. The injector consisted of a coflow reactor wherein water was introduced as a jet into liquid CO2, causing vigorous mixing of the two immiscible fluids to promote the formation of CO2 hydrate that is stable at ambient pressures and temperatures typical of ocean depths greater than approximately 500 m. Using flow rate ratios of water and CO2 of 1:1 and 5:1, particulate composites of CO2 hydrate/liquid CO2/seawater phases were produced in seawater at depths between 1100 and 1300 m. The resultant composite particles were tracked by a remotely operated vehicle system as they freely traveled in an imaging box that had no bottom or top walls. Results from the field experiments were consistent with laboratory experiments, which were conducted in a 70 L high-pressure vessel to simulate the conditions in the ocean at intermediate depths. The particle velocity and volume histories were monitored and used to calculate the conversion of CO2 into hydrate and its subsequent dissolution rate after release into the ocean. The dissolution rate of the composite particles was found to be higher than that reported for pure CO2 droplets. However, when the rate was corrected to correspond to pure CO2, the difference was very small. Results indicate that a higher conversion of liquid CO2 to CO2 hydrate is needed to form negatively buoyant particles in seawater when compared to freshwater, due primarily to the increased density of the liquid phase but also due to processes involving brine rejection during hydrate formation.