Synthesis Of Microspheres Research Articles

Synthesis of Porous NiMo Sulfide Microspheres for High-Performance Dye-Sensitized Solar Cells and Supercapacitor

Novel hierarchical porous NiMoS4 microspheres with high electrochemical performance was successfully prepared using a facile one-step hydrothermal method. The dual application of porous NiMoS4 microspheres in energy harvesting and storage (i.e., dye-sensitized solar cells (DSSCs) and supercapacitors (SCs), respectively) is explored. In contrast to NiS2 nanosheets, MoS2 nanosheets and Pt counter electrodes (CEs), the NiMoS4 microspheres CE demonstrated the lowest charge transfer resistance and highest electrocatalytic activity for the I[Formula: see text]/I− redox couple reaction. The NiMoS4-based DSSC showed a higher power conversion efficiency (8.9%) even than that of Pt-based DSSC (8.7%) under simulated standard global AM 1.5[Formula: see text]G sunlight (100[Formula: see text]mW[Formula: see text]cm[Formula: see text]). As an electroactive material for SCs, the assembled NiMoS4//AC asymmetric supercapacitor showed excellent specific capacitance (118.7[Formula: see text]F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text][Formula: see text], high energy density of 42.2[Formula: see text]Wh[Formula: see text]kg[Formula: see text] (with a power density of 799.2[Formula: see text]W[Formula: see text]kg[Formula: see text], and superior cycling durability with a specific capacitance retention of 79.5% after 9000 cycles at 3[Formula: see text]A[Formula: see text]g[Formula: see text].

Synthesis, characterization and microwave transparent properties of Mn3O4 microspheres

We synthesized a kind of novel hierarchical Mn3O4 spinel metal oxide with hollow core–shell structures by a facile one-step hydrothermal route with a further calcination process. The crystal structure and micro-morphology of these samples were characterized in detail. When employed as the microwave transmission material, the Mn3O4 microspheres calcined at 300 °C exhibit excellent wave-transparent property. Therefore, it is believed the Mn3O4 microspheres are an ideal candidate for next-generation wave-transparent materials.

Fluoride-tuned synthesis of hematite micro-spheres coated with ultrafine particles for smart detection of acetone

In this study, hematite (α-Fe2O3) micro-spheres coated with ultrafine particles (MSUPs) have been obtained for sensitive acetone sensors via first hydrothermal process with NH4F as the morphological regulator and then annealing of akaganéite. The role of fluoride ion concentration in precursor solution on the morphology has been demonstrated, and the corresponding reaction mechanism was discussed as well. The α-Fe2O3 MSUPs with 0.45 M NH4F (F0.5) in the precursor solution showed the highest response towards acetone compared to other α-Fe2O3 samples. Our α-Fe2O3 MSUPs sensors have potential in sensitive acetone detection.

Synthesis of degradable-polar-hydrophobic-ionic co-polymeric microspheres by membrane emulsion photopolymerization: In vitro and in vivo studies

The synthesis of microspheres for tissue regeneration requires good control over the particle size and size distribution. This is particularly important when considering the immune response that may be triggered by the presence of particles in tissue. This report outlines the design of an injectable microsphere system using a low-inflammatory, degradable-polar-hydrophobic-ionic polyurethane, termed D-PHI, and investigates the system’s performance in vitro and in vivo. Crosslinked polyurethane microspheres were prepared via a rapid and controlled process based on membrane emulsion and subsequent photopolymerization. The fabrication process efficiently generated microspheres with a narrow size distribution (12 ± 2 μm, PDI = 0.03). The D-PHI microspheres exhibited a slow and controlled degradation and a high capacity for water uptake. Water within the particles existed primarily within the pores of the particles and to a lesser degree within the polymer matrix itself. D-PHI microspheres supported human endothelial and fibroblast cell growth, and they maintained human blood-derived monocytes in a low-inflammatory state. Sub-acute toxicity was assessed for the particles after being administered via intramuscular injection in the gastrocnemius muscle of rats. Cellular infiltration and vascularization into the tissue region where the particles were deposited were observed along with an absence of a fibrous capsule around the particles. The microspheres did not cause elevated human monocyte induced inflammatory character, and supported tissue integration without a prolonged inflammatory response in the rat muscle. These injectable, degradable and low-inflammatory microspheres provide an attractive system for potential drug delivery and tissue regeneration applications in future studies. Statement of SignificanceBiodegradable, synthetic polymers are attractive candidates for generating tailored drug delivery vehicles and tissue scaffolds owing to their diverse chemical and physical properties that can be customised for delivering defined macromolecules at specific sites in the body. The past two decades have yielded interesting work exploring the fabrication of polymer microspheres with a narrow size distribution. However, the markedly low number of synthetic polymer chemistries currently used for microsphere production exhibit elevated proinflammatory character, both acute and chronic. Furthermore, a limited number of studies have explored the biocompatibility and immune response of polymeric microspheres with human primary cells and in vivo. In the current study, a method was conceived for efficiently generating low-activating polyurethane microspheres with respect to in vitro monocytes and in vivo macrophages. The biodegradable polyurethane, which contained multiple chemistry function and which has previously demonstrated anti-inflammatory properties in film and mm scale scaffold form, was selected as the base material. In this work we undertook the use of a room temperature membrane emulsification photopolymerization approach to avoid the need for high temperature cures and the use of solvents. The response of immune cells to the microspheres was studied with human primary cells and in the rat gastrocnemius muscle. The present work reveals important progress in the design of microspheres, with well-characterized low monocyte-activating properties and the translational advantages of a synthetic polyurethane which could be investigated in future studies for potential macromolecule delivery and tissue regeneration applications.

Space-Confined Polymerization: Controlled Fabrication of Nitrogen-Doped Polymer and Carbon Microspheres with Refined Hierarchical Architectures.

The construction of refined architectures plays a crucial role in performance improvement and application expansion of advanced materials. The synthesis of carbon microspheres with a refined hierarchical structure is still a problem in synthetic methodology, because it is difficult to achieve the necessary delicate control of the interior structure and outer shell across the microscale to nanoscale. Nitrogen-doped multichamber carbon (MCC) microspheres with a refined hierarchical structure are realized here via a surfactant-directed space-confined polymerization strategy. The MCC precursor is not the traditional phenolic resol but a new kind of 2,6-diaminopyridine-based multichamber polymer (MCP) with a high nitrogen content up to 20 wt%. The morphology and sizes of MCP microspheres can be easily controlled by a dual-surfactant system. The as-synthesized MCC with a highly microporous shell, a multichamber inner core, and beneficial N-doping can serve as a promising supercapacitor material.

Synthesis and assessment of drug-eluting microspheres for transcatheter arterial chemoembolization

Transcatheter arterial chemoembolization (TACE) is well known as an effective treatment for inoperable hepatocellular carcinoma (HCC). In this study, a novel embolic agent of ion-exchange poly(hydroxyethyl methacrylate-acrylic acid) microspheres (HAMs) was successfully synthesized by the inverse suspension polymerization method. Then, HAMs were assessed for their activity as an embolic agent by investigating morphology, particle size, water retention capability, elasticity and viscoelasticity, microcatheter/catheter deliverability, cytotoxicity, renal arterial embolization to rabbits and histopathological examinations. The ability of drug loading and drug eluting of HAMs was also investigated by using doxorubicin (Dox) as the model drug. HAMs showed to be feasible and effective for vascular embolization and to be as a drug vehicle for loading positively charged molecules and potential use in the clinical interventional chemoembolization therapy. Statement of significanceA novel embolic agent of ion-exchange poly(hydroxyethyl methacrylate-acrylic acid) microspheres (HAMs) was successfully synthesized by the inverse suspension polymerization method and was used as a drug vehicle to load positively charged molecules by ion absorption. Then, a series of assessments including physicochemical properties, mechanical properties, drug-loading capability, and embolic efficacy were performed. Surface and cross-section morphology and pore size of fully hydrated HAMs were first investigated by Phenom ProX SEM, which intuitively disclosed the “honeycomb” network morphology. HAMs also showed to be feasible and effective for vascular occlusion and have potential use in clinical interventional embolization therapy.

Controllable synthesis of hollow microspheres with Fe@Carbon dual-shells for broad bandwidth microwave absorption

Lightweight and high-performance microwave absorption materials with satisfactory absorption capability over broad frequency ranges are urgently required for electronic, aerospace and defense applications. Herein, an efficient and scalable approach is designed for synthesizing dual-shelled and hollow Fe@C microspheres by coating a ferric precursor on sulfonated polystyrene (PS) microspheres in a buffer solution and a thin layer of polydopamine (PDA) followed by annealing at 600 °C to decompose the internal PS cores and carbonize the external PDA shell. The resulting amorphous carbon shell ensures the formation of metallic Fe by a carbothermal reaction and stabilizes the hollow and spherical architecture. The generated Fe nanoparticles and the carbon layers combine the magnetic and dielectric losses together, improving the impedance matching and thus enhancing the microwave absorption performances over a broad frequency range. The minimum reflection loss of the hollow microspheres is as low as −54.4 dB at 8.8 GHz at a thickness of 4.5 mm and its effective absorption bandwidth is as broad as 8.1 GHz at a thickness of 3 mm, covering the entire X-band frequency range. This work provides an efficient and scalable approach for fabricating dual-shelled and hollow-structured Fe@C microspheres as lightweight and highly efficient microwave absorbers.

Synthesis and characterization of mesoporous polymeric microspheres of methacrylic derivatives of aromatic thiols

The paper presents the synthesis and characterization of mesoporous microspheres of derivatives of three aromatic thiols: S-phenyl 2-methylprop-2-enethioate (PSM), S,S′-thiodi-4,1-phenylenebis(thiomethacrylate) (DMSPS), and bis[4(2-hydroxy-3-methacryloyloxypropoxy)phenyl]sulfide (BES.DM) with divinylbenzene (DVB). The microspheres were obtained by the emulsion-suspension polymerization procedure. The chemical and porous structure, morphology, and properties of the microspheres were analyzed by attenuated total reflection-Fourier transform infrared (ATR/FT-IR) spectroscopy, low-temperature nitrogen adsorption data, optical microscope MORPHOLOGI G3, differential scanning calorimetry (DSC), and wavelength dispersive X-ray fluorescence (WD-XRF). Moreover, studies on the Pb(II) ions sorption process were carried out on the above mentioned compounds. The sorption kinetics and mechanism were described by the pseudo-first order, pseudo-second order, and intraparticle diffusion models. The sorption equilibria were described by the Langmuir and Freundlich isotherms. The PSM-DVB, DMSPS-DVB, and BES.DM-DVB microspheres exhibit high thermal resistance and good adsorption properties of Pb(II) ions. The best adsorption properties for the examined microspheres were obtained at pH 5. The highest monolayer adsorption capacity determined by Langmuir isotherm was obtained for the DMSPS-DVB microspheres and was equal to 22.54 mg/g. The preliminary studies show that the synthesized microspheres can be used as heavy metal ion sorbents from aqueous solutions.

Facile synthesis of mesoporous ZnCo2O4 hierarchical microspheres and their excellent supercapacitor performance

ZnCo2O4 hierarchical microspheres assembled by a large amount of porous nanosheets with 15 nm in thickness were synthesized via a simple solvothermal approach in a mixed solvent containing water and ethylene glycol (EG), and combined with a subsequent calcination process at 400 °C in air. These nanosheet-based ZnCo2O4 microspheres possessed a high BET surface area of 67.1 m2 g−1 and pore size distribution centered at 4.6 nm with a mean pore diameter of 28.6 nm. The pseudocapacitive performances of such ZnCo2O4 electrode material were investigated by the related electrochemical tests in 2 M of KOH electrolyte, and the results indicated that a highly specific capacitance of 689 F g−1 at 1 A g−1 and a good rate capability of 81.3% capacitance retention at 15 A g−1 could be achieved. After a consecutive 5000 charge-discharge cycling process at 5 A g−1, the ZnCo2O4-modified electrode exhibited 98.7% specific capacitance retention of its original value, suggesting a superior long-life cycling durability. The excellent electrochemical performances of the ZnCo2O4 hierarchical microspheres make it a promising and suitable electro-active material for energy storage. The current synthetic process is facile without using any sophisticated instruments or expensive reagents. The strategy can be further adopted for the synthesis of other binary transitional metal oxides with superior electrochemical properties by simple replacement of starting salts.

Poly(glycidyl methacrylate-co-1,4-dimethacryloyloxybenzene) monodisperse microspheres - synthesis, characterization and application as chromatographic packings in RP-HPLC

The study describes the synthesis of porous microspheres with glycidyl methacrylate (GMA) and 1,4-dimethacryloyloxybenzene (DMB) using the seed swelling polymerization. As a shape template the polystyrene (PS) seed obtained via the dispersion polymerization was used. Oxirane, esters and aromatic groups are present in the structure of copolymers. Changing the reaction mixture composition – the amounts of crosslinking monomer and PS seed, almost monosized poly(GMA-co-DMB) microspheres of the diameters in the range of 8.20 μm to 11.61 μm and highly developed porous structure with specific surface area (SBET) up to 353 m2/g were obtained. The pore size distribution and the volume of pores measured for the copolymer in the dry and the swollen states differ. In the dry state in the internal copolymer structure mesopores were observed whereas in the swollen state additionally micro- and macropores appeared. The copolymer obtained with the equimolar mixture of monomers was applied as the column packing material and tested in the reverse-phase HPLC. The isocratic separation of alkylbenzenes was achieved with satisfactory resolution using the 100 × 4.6 mm i.d. column with the acetonitrile/phosphate buffer mobile phase. The theoretical plate numbers up to 12,000 were obtained for benzene as the analyte. Using the retention indices for the test compounds it was found that the retention mechanism on the studied copolymer is the sum of π-π hydrophobic interactions, dipole interactions and to a smaller extent of hydrogen acceptance interactions rather than hydrogen donation interactions.

Synthesis and characterization of silver nanoparticle-loaded amorphous calcium phosphate microspheres for dental applications.

The goals of this work were (1) to synthesize composite nanostructures comprised of amorphous calcium phosphate (ACP) loaded with silver nanoparticles using a spray pyrolysis method and (2) to demonstrate their potential for use in dental adhesives. Release of silver ions from these nanostructures could provide antibacterial activity, while release of calcium and phosphate ions could promote tooth remineralization. Precursor solutions were prepared with varying silver concentrations corresponding to 5, 10, and 15 mol% of the calcium content, then sprayed into a furnace (550 °C) as droplets with a mean diameter near 2 μm. In this process, each droplet is converted into a single solid microsphere via rapid heating. The synthesized particles were collected using a polymeric filter installed at the end of the reaction zone. Different quantities (2, 5, and 10 wt%) of the nanocomposite material were mixed with a commercially available dental adhesive (Single Bond, 3M ESPE) which was then polymerized into discs for incubation in a solution simulating cariogenic conditions. Release of silver, calcium and phosphorus ions into the solution was measured for 1 month. The nanostructures of ∼10 nm silver nanoparticles embedded into 100 nm to 2 μm ACP particles demonstrated good dispersion in the adhesive resin blend, which in application would shield surrounding tissues from direct contact with silver. The composite nanoparticles provided a quick initial release of ions after which the concentration of calcium, phosphorous, and silver in the incubation solution remained constant or increased slightly. The dispersibility and ion release of the new nanostructures may offer potential for use in dental materials to achieve anti-bacterial and remineralization effects.

Synthesis and characterization of polymer microspheres and its application for phenol adsorption

Synthesis and characterization of polymer microspheres and its application for phenol adsorption

Laser-Induced-Electro-Explosion Synthesis of Powder Materials (LIEES)

In this paper, a method for the synthesis of microspheres containing titanium carbide by laser radiation is described. The formation of microspheres is carried out by the action of femtosecond laser radiation on the surface of titanium in the reaction medium - the saturated hydrocarbon. Hexane was used as a hydrocarbon. The obtained microspheres have an average size of 1-3 μm and can be used in applications of additive engineering, powder metallurgy as the main raw material, or as an alloying additive. To increase the efficiency of particle output, a method of laser action combining with electric current is proposed. The behavior of an electric discharge in the plasma channel area was studied.

Synthesis and characterization of carbon microspheres from rubber wood by hydrothermal carbonization

AbstractBACKGROUNDCarbon is the raw material for many commercial products; conventionally their production is from non‐renewable sources such as petroleum coke, pitch and coal. Recently carbon has been obtained from bioresources because of their renewability and high lignocellulosic content. This article details the synthesis of carbon microspheres from rubber wood, which is one of the largest commodity plants, via hydrothermal carbonization (hydrothermal rubber wood carbon; HTRW carbon) and evaluation of their characteristics.RESULTSTwo sets of carbon were synthesized: (i) in the first set, excess of water (20–40 × weight of biomass) was used in the hydrothermal process at 180–260 °C for 3–9 h; and (ii) in the second set, water ratio was 25–35 × weight of biomass and the hydrothermal carbonization (HTC) reaction temperature was fixed at 260 °C. The H/C and O/C ratios of starting rubber wood were ∼1.78 and ∼0.85, respectively, which upon processing through the first strategy resulted in H/C ∼0.78 and O/C ∼0.29; thereby suggesting increased condensation under HTC. On the other hand, the carbonization process was accelerated by water when the temperature was maintained at 260 °C; Fourier transform infrared (FTIR) studies show that this carbon has a different chemical structure from the starting rubber wood. Scanning electron microscopy (SEM) images showed that HTRW carbon was in the form of microspheres (size ∼1.5–5 µm).CONCLUSIONHTRW carbon with carbon content as high as 68% was developed from rubber wood biomass by hydrothermal processing of a mixture containing 35 times more water than the solid raw biomass at a temperature of 260 °C for 7 h. © 2018 Society of Chemical Industry

Effects of different parameters on the synthesis of silica aerogel microspheres in supercritical CO2 and their potential use as an adsorbent

Synthesis of metal oxide microspheres in supercritical carbon dioxide (SCO2) is very attractive for a wide range of applications such as catalysis, controlled release, and separation science due to their identical properties. The aim of this study is the synthesis of silica microspheres (SM) in SCO2 by sol–gel method. The effects of temperature, pressure, flow rate, time, co-solvent and its ratio on the synthesis of silica microspheres in SCO2 were investigated. The synthesized microspheres were characterized by several techniques including field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), and surface area analysis. The results indicated that the optimum condition for the synthesis of SM was determined at 150 bar, 80 °C, and 2.5 mL min−1 of SCO2 flow rate. The usability of SM as an adsorbent for the removal of dyes and heavy metals from aqueous solutions was also examined. Kinetic and isotherm studies for the adsorption of Pb(II) ions and Acid Blue 260 (AB260) onto SM were carried out.

Facile synthesis of TiO2 microspheres via solvothermal alcoholysis method for high performance dye-sensitized solar cells

TiO2 microspheres (MS-TiO2) are synthesized by a facile one-step nonaqueous solvothermal alcoholysis method. Without any post-processing, the as-prepared MS-TiO2 constituted by high crystallinity anatase nanoparticles (∼18 nm) exhibits large specific surface area (114 m2 g−1), high porosity (71%), and wide pore size distribution (centered at ∼12.4 nm, average pore diameter is ∼20.9 nm). Moreover, the MS-TiO2 shows superior light scattering ability. When employed as photoanode in dye-sensitized solar cells, the MS-TiO2 films display excellent dye loading capacity and good light-harvesting capabilities in the range of 400–700 nm. Consequently, an ultrahigh short circuit current density up to 20.41 mA cm−2 and a high power conversion efficiency of 10.35% are achieved by the MS-TiO2 based solar cells.

Nickel vanadate microspheres with numerous nanocavities synthesized by spray drying process as an anode material for Li-ion batteries

For use in next-generation energy storage applications, including electric vehicles, capacity and cycle life of lithium ion batteries need further improvement. Moreover, to achieve fast lithiation kinetics of the electrode materials, high power density and quick charging ability are necessary. Nickel vanadate (Ni3V2O8) microsphere with tens of nanocavities is one of candidates for anode materials suitable for lithium ion batteries. The synthesis of microspheres is possible by a pilot-scale spray drying process and facile one-step oxidation heat treatment. Dextrin, which is present in the microspheres after spray drying process, plays a key role in the formation of nanocavities. Oxidation at different temperatures yields carbon composite microspheres with nanocavities and hierarchical Ni3V2O8 microspheres with nanocavities. The nanocavities facilitate electrolyte contact with the electrode material and alleviate volume change during lithiation/delithiation. The merits of the nanocavities in the Ni3V2O8 microspheres enable a high discharge capacity of 1045 mA h g−1 for the 2nd cycle at 1 A g−1 and long cycle life. Furthermore, Ni3V2O8 microspheres deliver a high discharge capacity of 612 mA h g−1 at a high current density of 6 A g−1.

Hierarchical flower-like conductive CoNiO2 microspheres constructed with ultrathin mesoporous nanosheets towards long-cycle-life hybrid supercapacitors

Highly conductive transitional metal oxides (TMOs) positive electrodes can well address intrinsic power mismatching issues between negative and positive electrodes for advanced asymmetric supercapacitors. Purposeful exploration and rational design of dynamical TMOs with favorable microstructures and high-rate pseudocapacitances are crucially desired for advanced hybrid devices. Herein, we report efficiently bottom-up synthesis of hierarchical flower-like conductive CoNiO2 microspheres (CNOMS) self-constructed with mesoporous (∼2.4 nm) ultrathin nanosheet subunits of approximately 3.5–4.8 nm in thickness. Our CNOMS appealingly promise a fast electron and ion transport, large electroactive surface and strong structure stability in one. As a virtue of the compositional/structural features, the obtained CNOMS electrode with a high loading of 5 mg cm−2 delivers large specific capacitances of ∼854.9 and ∼414.5 F g−1 at high current rates of 1 and 20 A g−1 in 2 M aqueous KOH electrolyte, much superior to those of monometallic nickel/cobalt oxides counterparts. Encouragingly, the CNOMS-based hybrid device exhibits high energy density of ∼36.2 Wh kg−1 at a power rate of 160.0 W kg−1, as well as ∼100.8% long-duration capacitance retention over 10000 consecutive charge/discharge cycles. More promisingly, our CNOMS specimen is substantially highlighted as competitive electrode for long-cycle-life hybrid supercapacitors.

Synthesis of multicore energetic hollow microspheres with an improved suspension polymerization-thermal expansion method

A novel energetic microsphere with multicore hollow structure and uniform particle size is prepared by an improved suspension polymerization-thermal expansion method with methyl methacrylate, azodicarbonamide (AC) and TiH2 powder as monomer, blowing agent and core material, respectively. The energetic hollow microspheres (EHMs) can play double roles as sensitizers and energetic additives in emulsion explosive, and experimental results show that the EHMs could increase the power of emulsion explosive without affecting its safety. This method provides a completely new idea for the development of high energy emulsion explosive.

Synthesis and Characterization of Chitosan Polyaniline Silver Microspheres

Synthesis and Characterization of Chitosan Polyaniline Silver Microspheres