Flower-like Particles Research Articles

Crystallization induced flower-like lactose as potential carriers for dry powder inhaler application

The study documents the flower-like lactose particles as potential carriers to improve Dry Powder Inhaler (DPI) efficiency. The lactose particles (LMx, LMf) are prepared by anti-solvent crystallization and compared with commercial lactose carriers (Inhalac 251; LMc). Formulations of 1.48% w/w drug loading are prepared using salbutamol sulfate (model drug) and different lactose carriers. The carrier properties are correlated with %FPF using principal component analysis. The analytical results confirm LMx is α-lactose monohydrate, LMf comprises α and β-lactose. Time-resolved crystal growth shows that the LMx particle is agglomerated structure while, LMf particle appear as flower-like structure of size (~45.37–63.92 μm) with high surface and aerodynamic properties compared to LMc. The in-vitro aerosolization studies resulted in higher fine particle fraction (%FPF) for formulations with LMx (~33.23%) and LMf (~44.85%) compared to LMc (~23.40%). The high %FPF is mainly attributed to the higher surface roughness, amorphicity, surface energy of engineered lactose carriers.

Preparation of flower-like titania particles from lithium titanate hydrate via acid treatment and hydrothermal crystallization

Preparation of flower-like titania particles from lithium titanate hydrate via acid treatment and hydrothermal crystallization

CO2 Capture and Crystallization of ATH Using Sodium Aluminate Solution in a Bubble Column Scrubber

In this work, sodium aluminate alkaline solution was used to capture CO2 in a continuous bubble column scrubber and aluminum tri-hydrate (ATH) precipitates were produced. As the sodium carbonate could be recycled after the filtrated solution was crystallized by evaporation, a novel CO2 capture process was developed successfully. There were five experimental operation variables, including solution flow rate (A), concentration of the solution (B), gas flow rate (C), CO2 gas concentration (D), and liquid temperature (E), with four levels to each variable. The influence of each variable on absorption efficiency (EF), absorption rate (RA), absorption factor (φ), mass transfer coefficient (KGa), and precipitation rate (RP) in a steady state was explored in this study. The Taguchi experimental design was adopted, and 16 experiments were performed; as the optimum operating conditions found in Taguchi analysis required further verification, there were a total of 21 experiments in the end. According to S/N analysis, the overall order of importance was D > A = B > C > E, meaning D (CO2 concentration) was most important and E (liquid temperature) was least important. In addition, the result also showed that the Rp was 1.25–2.0 times higher than the RA. The obtained powder was mainly ATH according to XRD analysis, with the crystal size ranging between 8.14 and 27.97 nm. However, the BET analysis showed its particle size range being 17.6–283.7 nm, indicating agglomeration for primary particles. The SEM analysis showed that there were flower-like, irregular, urchin-like, elongated, and amorphous particles. The solutions from five groups of optimum conditions were used to recycle the sodium carbonate experiments. After evaporation and crystallization of the filtrated solutions, the energy loading was found to be 1.70–2.56 GJ/t-solvent, illustrating the superiorities of low energy consumption. The precipitated powders were verified to be sodium carbonate by FTIR, which is a valuable constituent.

Enhancing pesticide droplet deposition through O/W Pickering Emulsion: Synergistic stabilization by Flower-like ZnO particles and polymer emulsifier

The effective deposition of pesticide droplets on the plant leaves is an important challenge. In this study, flower-like ZnO particles were fabricated via a simple precipitation method at room temperature and were chosen as a stabilizer for Pickering emulsions. A 3% mefentrifluconazole Pickering emulsion with 70 vol% water phase fractions can be easily prepared using 0.5 wt% ZnO particles and 0.1 wt% A-7 as a dual emulsifier, thereby reducing the dosage of conventional surfactants. The simultaneous adsorption of ZnO particles and A-7 at the oil–water interface in the form of a densely packed layer exhibits synergistic effect, preventing droplet coalescence via a steric mechanism. The Pickering emulsion effectively inhibits the rebounding of droplets and deposits on rice leaves with different inclination angles in 1.5 ms, following which it spreads to the maximum wetting area within 360 s. In addition, the flower-like ZnO particles can be inlaid and adhered to various micro-nanostructures on the surface of a rice leaf. Owing to the topology effects between each other, it is beneficial for droplets to deposit on the leaf surface. The average control efficacy reached 90.37%, thereby improving the effective utilization of pesticides. This study provides a new opportunity for the application of flower-like ZnO particles as Pickering emulsion stabilizer in the agricultural field.

Calcium carbonate coating on Ti-6Al-4 V by carbonate diffusion in calcium source at room temperature

Titanium (Ti) and its alloy have been extensively used in orthopaedic and dental implants due to its excellent biocompatibility. However, there is still a need to improve bone integration at the early stage of implants. This study was aimed to fabricate Ti-6Al-4 V alloy coated with a bioresorbable and osteoconductive calcium carbonate (CaCO3). The coating was prepared by carbonate diffusion in the presence of calcium ions. The coating was characterized by grazing incidence X-ray diffraction (GIXRD), scanning electron microscope (SEM), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The GIXRD confirmed the formation of calcite phase on the surface of the Ti-6Al-4 V. The scanning electron microscope (SEM) showed that the products exhibited rhombohedral, spherical, and flower-like morphologies. The flower-like particles were orderly constructed from smaller plate-like particles with an average diameter of 5 μm. The calcium content of the coating was approximate 5.05 mg/mm2 as detected by the ICP-AES.

Solvothermal Synthesis of Flower-Flakes Like Nano Composites of Ni-Co Metal Organic Frameworks and Graphene Nanoplatelets for Energy Storage Applications

Solvothermal synthesis of Ni-Co-metal organic framework (MOF)/graphene nanoplatelets (GNPs) nanocomposites was done for their potential application as electrode material in energy storage devices. Addition of GNPs and metallic precursors together with 2-methylimedazole in the same autoclave reactor produced smooth-nanoflakes like Ni-Co-MOF/GNPs nanocomposites as evaluated by scanning electron microscopy (SEM). X-ray diffraction (XRD) analysis showed the presence of GNPs where GNPs do not affect the growth of MOF crystals and Ni-Co-MOF crystalline phases remain unaffected in the composite structure. Fourier transform infrared (FTIR) spectroscopy analysis confirmed the presence of organic links forming nickel-cobalt metal cations framework. Electrochemical testing (CV, EIS and GCD) of the produced composites demonstrated that GNPs addition can enhance the charge storage performance of MOF nanocomposites. The largest cycle area and most discharge time have been shown by Ni-Co-MOF/GNP-50 composite electrode that delivered the highest specific capacity values (313Cg−1 @1Ag−1), good reversibility and low internal resistance and charge transfer resistance, owing to efficient dispersion of flower-like flaky particles and efficient interconnected paths for ion and electron transportation. Moreover, Ni-Co-MOF/GNP-50 composite exhibited good thermal stability with 28% weight loss during thermogravimetric analysis. The electrochemical evaluations performed on asymmetric supercapacitor (ASC) real device expressed a specific capacity of 136.5 Cg−1@0.5Ag−1, maximum energy density of 32.2 Whkg−1@425 Wkg−1 and maximum power density of 17000 Wkg−1@12.8 Whkg−1. Moreover, the device showed a stability performance of 92.5%@10 Ag−1 after 5000 CD cycles.

Electrochemical deposition of flower-like nanostructured silver particles with a PVA modified carbon cloth cathode.

A novel electrochemical method for preparing flower-like nanostructured silver particles using polyvinyl alcohol (PVA) modified carbon cloth as a cathode is reported. The method does not involve the use of any morphological control agents in aqueous solution. The morphology of the silver nanoparticles obtained was studied using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The effects of the operating conditions on the deposited silver nanoparticles were investigated. It was found that PVA concentration for carbon cloth modification had a significant effect on the deposited silver morphology. With 1% PVA modification, current density of 10 μA cm−2 and silver nitrate concentration of 1 mM, a flower-like nanostructured silver with petal thickness of 100 nm can be prepared. With the reaction proceeding, silver nanocrystals nucleated on the cathode in a few seconds, then the nuclei grew and the rudimental flower-like silver started to form in 1 min. The perfect flower-like nanostructure of silver was formed in 20 min. However overlong reaction time led to micrometer sized blocks. The specific silver nanostructure growth might be attributed to the silver ion concentration gradient caused by reaction and diffusion rate and the effects of PVA.

Flower-Like Colloidal Particles through Precipitation Polymerization of Redox-Responsive Liquid Crystals.

We report on the synthesis of monodisperse, flower‐like, liquid crystalline (LC) polymer particles by precipitation polymerization of a LC mixture consisting of benzoic acid‐functionalized acrylates and disulfide‐functionalized diacrylates. Introduction of a minor amount of redox‐responsive disulfide‐functionalized diacrylates (≤10 wt %) induced the formation of flower‐like shapes. The shape of the particles can be tuned from flower‐ to disk‐like to spherical by elevating the polymerization temperature. The solvent environment also has a pronounced effect on the particle size. Time‐resolved TEM reveals that the final particle morphology was formed in the early stages of the polymerization and that subsequent polymerization resulted in continued particle growth without affecting the morphology. Finally, the degradation of the particles under reducing conditions was much faster for flower‐like particles than for spherical particles, likely a result of their higher surface‐to‐volume ratio.

Self-Assembly Mechanism of Complex Corrugated Particles.

A variety of inorganic nanoscale materials produce microscale particles with highly corrugated geometries, but the mechanism of their formation remains unknown. Here we found that uniformly sized CdS-based hedgehog particles (HPs) self-assemble from polydisperse nanoparticles (NPs) with diameters of 1.0-4.0 nm. The typical diameters of HPs and spikes are 1770 ± 180 and 28 ± 3 nm, respectively. Depending on the temperature, solvent, and reaction times, the NPs self-assemble into nanorods, nanorod aggregates, low-corrugation particles, and other HP-related particles with complexity indexes ranging from 0 to 23.7. We show that "hedgehog", other geometries, and topologies of highly corrugated particles originate from the thermodynamic preference of polydisperse NPs to attach to the growing nanoscale cluster when electrostatic repulsion competes with van der Waals attraction. Theoretical models and simulations of the self-assembly accounting for the competition of attractive and repulsive interactions in electrolytes accurately describe particle morphology, growth stages, and the spectrum of observed products. When kinetic parameters are included in the models, the formation of corrugated particles with surfaces decorated by nanosheets, known as flower-like particles, were theoretically predicted and experimentally observed. The generality of the proposed mechanism was demonstrated for the formation of mixed HPs via a combination of CdS and Co3O4 NPs. With unusually high dispersion stability of HPs in unfavorable solvents including liquid CO2, mechanistic insights into HP formation are essential for their structural adaptation for applications from energy storage, catalysis, water treatment, and others.

Influence of calcination temperature in synthesizing eggshell-derived calcium phosphate

Hydroxyapatite (HA) has been used in the biomedical field not only due to its structural resemblance to the natural bone but also for its being bioactive and thermodynamically stable in the body fluid. Generally, the synthesis of HA particles through various available methods has been directed in controlling the growth of HA particles size as this characteristic has an implicit effect on the mechanical properties, biocompatibility and biological activity of HA in the application. Raw materials for the synthesis of HA can be obtained from commercial chemicals and natural sources. Natural source, particularly eggshell has been favoured due to the presence of other elements inherent in the eggshell that induced better cell response. In this study, a direct solid-state method was used to synthesize HA powder utilizing a Ca source in carbonated form from calcined discarded eggshells. The milled mixture of calcined eggshell powder and phosphorus precursor was subjected to heat treatment at various temperatures in studying the influence of different calcination temperatures on the HA phase stability, particle size and morphology through X-Ray Diffractometer and Scanning Electron Microscope analysis. Overall, HA powder consisted of flower-like particles was successfully obtained from eggshell through the combination of dry powder mixing and heat treatment at 800 °C.

Morphology and Catalytic Performance of MoS2 Hydrothermally Synthesized at Various pH Values

Although preparation conditions are known to affect the morphology and catalytic performance of hydrothermally synthesized MoS2, the influence of pH remains unclear. Herein, unsupported MoS2 was prepared from ammonium tetrathiomolybdate (ATTM) by a hydrothermal reaction at various pH values under a reaction pressure of 2 MPa. The physical and chemical properties of the MoS2 samples were characterized, and the catalytic performance for CO methanation was examined. With increasing pH, the morphology of the MoS2 particles transformed from aggregates of irregular grain-like particles to flower-like particles through the agglomeration of fine mesoporous nanoflakes. Hydrothermal synthesis at a pH of 9.5 increased the MoS2 crystallinity by enhancing the stacking of the (0 0 2) lattice plane. The MoS2 samples prepared at pH 7.0 and 9.5 showed increased CO conversion during methanation, which was associated with a low concentration of Mo5+ species and the presence of surface sulfate species. Thus, a high pH during catalyst preparation may promote the complete decomposition of ATTM to MoS2 and the formation of sulfur vacancies, which can facilitate methanation.

Bifunctional crystalline microporous organic polymers: Efficient heterogeneous catalysts for the synthesis of 5-hydroxymethylfurfural

Developing efficient catalysts for the synthesis of 5-hydroxymethylfurfural (HMF) from biomass resources is very demanding as it is an important renewable platform chemical for the synthesis of biofuels, polymers and fine chemicals. Here, we have designed two new crystalline microporous bi-functional porous organic polymers through the extended aromatic substitution reaction under refluxing conditions. Porous polymers containing sulfonic acid and secondary amine groups are two reactive catalytic centres for carrying out the bi-functional heterogeneously catalysed reactions. Bifunctionalized porous polymers POPDS and POPSDS are synthesized through the reaction of 2,2′-benzidinedisulfonic acid and 4,4′-diaminostilbene-2,2′-disulfonic acid with cyanuric chloride, respectively. The materials were characterized thoroughly using powder X-ray diffraction, N2 sorption, FTIR, solid state 13C CP MAS NMR spectroscopy, FE-SEM, HR-TEM, XPS and TG/DTA analysis. These two crystalline porous polymers possesses good surface acidic and basic sites, and having flower-like and spherical particle morphologies. POPDS and POPSDS exhibited superior catalytic activity for the conversion of different small carbohydrates to 5-hydroxymethylfurfural (HMF) under microwave irradiation. Moreover, the recyclability tests of these catalysts revealed good durability up to sixth consecutive reaction cycles, suggesting the future potential of these catalysts in the sustainable synthesis of HMF.

Tuning Sugar-Based Chiral and Flower-Like Microparticles.

Unique supermolecular structures as chiral and flower-like microparticles and the precise tuning of the morphologies hold immense promise for a variety of applications. Examples of such structures deriving from monosaccharides are still rare, and a general understanding is also lacking. Herein, it is shown that chiral, flower-like, or solid microparticles can be tuned by only using monosaccharide esters without external stimuli. Chiral "left-handed" (counterclockwise) and "right-handed" (clockwise) morphologies can be induced by d- and l-glucose stearoyl esters. In comparison, other monosaccharides, i.e., galactose, mannose, and xylose, cannot formed chiral particles and generated diverse other morphologies of the supermolecular microparticles based on their distinct molecular configurations. Due to the numbers of side chains and the bond orientations, microparticles with solid and porous flower-like morphologies can be obtained. While glucose and xylose esters only lead to solid microparticles, mannose and galactose generate porous flower-like particles. These findings suggest a general method to design and control the superstructures by using monosaccharide backbones with diverse molecular configurations.

Superhydrophobic and photocatalytic self-cleaning cotton fabric using flower-like N-doped TiO2/PDMS coating

Self-cleaning fabrics can be developed based on introducing two mechanisms of superhydrophobicity and photocatalytic activity to conventional fabrics. However, there are some downsides such as inefficiency of superhydrophobic coatings against oily contaminants and low effectiveness of photocatalytic surface treatments under visible light which have restricted the widespread applications of these functional products. This research presents the development of self-cleaning cotton fabric with dual functionalities of superhydrophobicity and photocatalytic activity using microhierarchial TiO2-based particles. It is aimed to fabricate fluorine-free durable superhydrophobic coatings with simultaneous photocatalytic self-cleaning under simulated sunlight. Fluorine-free coating formulations composed of flower-like particles, either TiO2 or nitrogen-doped TiO2, and polydimethyl siloxane (PDMS) polymer were applied to cotton fabrics using a facile dip-coating method. The self-cleaning performance of fabrics was assessed based on their superhydrophobicity and effective removal of oil-based stains under simulated sunlight. Additionally, the impact of nitrogen doping on enhancing the photocatalytic activity of flower-like TiO2 particles was investigated. The obtained results demonstrated that the presence of both PDMS and hierarchical particles generated excellent superhydrophobicity on the cotton fabric with a water contact angle of 156.7° ± 1.9°. In addition, the coated fabric exhibited highly efficient photocatalytic activity, decomposing absorbed stains after 30 min of irradiation. Nitrogen doping process significantly boosted the photocatalytic activity of TiO2 particles in degrading food stains and Rhodamine B dye solution. The developed fabrics showed high robustness against chemical and physical durability tests.

Tin(IV) oxide nanoparticulate films for aqueous dye-sensitized solar cells

Reported solar conversion efficiencies of aqueous dye-sensitized solar cells (DSSCs) trail those of traditional organic electrolyte-based systems but offer the potential for lower environmental impact and overall cost. Methods for improving the photochemical activity of aqueous DSSCs could also impact progress in related fields such as solar fuels and solar batteries. This work presents the first study solely focused on the use of SnO2-based photoanodes for use in aqueous DSSCs. Material design and interfacial engineering are critical to the effective use of SnO2 in this context, and it is found that mesoporous films comprised of both large 1–2 μm flower-like SnO2 particles and small 10–20 nm spherical SnO2 particles provide better performance than films composed of only one particle type. Insulating TiO2 coatings further improve the performance, and this work presents a facile liquid phase deposition strategy under ambient conditions using an aqueous TiF62- solution that proves more effective than the widely used method with TiCl4 for fabricating high-performing SnO2@TiO2 photoanode surfaces. The best aqueous DSSCs reported here using cis-bis(isothiocyanato)-bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II) dye and simple I3-/I- electrolyte achieve a power conversion efficiency of 0.7% which eclipses the first reported TiO2-based DSSC using otherwise identical dye and electrolyte composition.

Synthesis and characterization of poly(vinylidene fuoride) composites with flower-like ZnO particles for flexible pipelines applications

Abstract In this paper, flower-like ZnO (FZnO) particles were synthesized through a facile method using different precursor content and reaction time. The as-prepared ZnO particles were then characterized by scanning electron microscopy (SEM), and the results showed the production of particles with varied aspect ratios (5–14). Composites of poly (vinylidene fluoride) (PVDF) with FZnO were prepared and also studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier-transform infrared (FTIR). A slight reduction of thermal properties was noticed, where the degradation temperature decreased from 439 °C for neat PVDF to around 431–438 °C for the PVDF composites with FZnO. Besides, an increase of β-crystals was observed by incorporating these particles, shifting from 31% (neat PVDF) to 37% in the composites. Furthermore, the permeability coefficient to CO2 reduced around 13%, indicated that the composites with the obtained flower-like ZnO particles might have potential applications as a barrier layer in oil ducts pipelines compared with neat PVDF.

Reverse micelle-mediated synthesis of plate-assembled hierarchical three-dimensional flower-like gamma-alumina particles

Herein, we report the synthesis of hierarchical three-dimensional (3D) γ-Al2O3 flower-like particles composed of randomly arranged nanoplates via a reverse micelle-mediated solvothermal method. A systematic time-dependent study was performed to reveal the changes in phase composition of these hierarchical nanostructures during the synthesis process. A mixture of boehmite (γ-AlOOH), gibbsite (Al(OH)3), and dawsonite (NaAlCO3(OH)2) is found at the initial growth stage, which is subsequently converted to boehmite after 24 h of reaction without any significant morphological change. The effects of important synthetic parameters, such as water, CTAB, and urea contents on the crystallite size, particle size distribution, and surface area of the obtained γ-Al2O3 products have also been thoroughly investigated. Higher concentration of CTAB is found to promote the formation of γ-AlOOH precursor with larger crystallite size and γ-Al2O3 products with narrower particle size distribution and larger surface area. In contrast, higher urea content leads to the generation of γ-AlOOH precursor with larger crystallite size and γ-Al2O3 product with wider particle size distribution and lower surface area. Further, higher water content tends to generate γ-AlOOH precursor with smaller crystallite size and γ-Al2O3 product with broader particle size distribution and higher surface area. The optimum hierarchical γ-Al2O3 flower-like sample exhibits high BET surface area and total pore volume of 214 m2 g−1 and 0.99 cm3 g−1, respectively. The highly porous structure of this sample is expected to provide numerous active sites and easy accessibility for reactants or products in catalytic applications.

Hollow flower-like nickel particles as the promoter of ammonium perchlorate-based solid propellant

Hollow flower-like nickel particles were prepared by a facile polyol method, and applied to solid propellant as combustion promoter. Ni[C2H4(NH2)2]3(COOH)2 complex was used to fabricate hollow flower-like intermediate in ethylene glycol (EG), and then the intermediate was calcined and auto-reduced in nitrogen to obtain the hollow flower-like nickel particles. The hollow particles' shell thickness is about 120 nm, and the petals' thickness of the flower structure is about 10 nm. Importantly, the hollow spheres' diameter can be accurately controlled from 200 nm to 2 μm by adjusting the concentration of complex Ni[C2H4(NH2)2]3(COOH)2 in the reaction solution. The growth of the hollow flower-like particles was illustrated as an extraordinary growth-shrink-collapse process by analyzing the intermediate's morphologies as reaction going on. By adding a certain amount (typically 5 wt%) of the prepared nickel powders, the exothermic decomposition of ammonium perchlorate, which is the main component of solid propellant, was well promoted. The decomposition temperature was decreased by about 140 °C, and the exothermic peak at higher temperature shifted to the lower temperature range, heat released of AP's decomposition also increased by about 150%.

Synthesis and characterization of pseudoboehmite by neutralization method

Pseudoboehmite was obtained through neutralization of ammonium aluminum sulfate solution [NH4Al(SO4)2·12H2O] with ammonia water [NH3 (aq)]. The neutralization process resulted in flake-like overlapping flower-like structures at 80 °C and 85 °C. When the temperature of the NH4Al(SO4)2·12H2O solution was raised to 90 °C, nanoparticles, microspheres with a diameter of less than 50 nm, were obtained. The (131) plane was studied by HRTEM imaging (high resolution transmission electron microscopy). Density functional theory was used to study the interface properties of the pseudoboehmite, and the surface energy and attachment energy were calculated for the optimized crystal planes of interest. The results show that the relaxed (131) plane has the lowest surface energy (0.0474 J/m2), and thus is the most stable surface. Additionally, the (200) plane of the pseudoboehmite has the lowest absolute value of attachment energy (0.2106 eV/unit), consistent with having the strongest X-ray diffraction peak and indicating that it is the preferred orientation. The formation mechanism of flower-like and microspherical particles is discussed, with consideration for solution temperature effects on morphology and the predicted equilibrium morphology and growth morphology of pseudoboehmite.

Efficient removal of various coexisting organic pollutants in water based on β-cyclodextrin polymer modified flower-like Fe3O4 particles

HypothesisThe construction of porous β-cyclodextrin polymer (β-CDP) modified flower-like Fe3O4 particles (CDP@Fe3O4) is expected to remove various organic pollutants from water, based on the larger specific surface area of flower-like Fe3O4 particles and the active sites provided by β-CDP. With the help of various noncovalent interactions, the removal ability of CDP@Fe3O4 for various water-soluble and water-insoluble organic pollutants were systematically studied. ExperimentsCDP@Fe3O4 were successfully synthesized and applied for the simultaneous removal of various organic pollutants with different electrical properties, structure and hydrophobicity. Adsorption efficiency, adsorption process, adsorption mechanism and the reusability of CDP@Fe3O4 for single pollutant and mixed pollutants were comprehensively investigated. FindingsCDP@Fe3O4 exhibited excellent adsorption capabilities for various pollutants. Importantly, when these pollutants were coexisting, CDP@Fe3O4 still maintained a comparable removal ability for various pollutants. Efficient removal of organic pollutants was attributed to varieties of noncovalent interactions between organic pollutants and CDP@Fe3O4, including hydrophobic interactions, hydrogen bonds, π-π and electrostatic interactions. These results revealed that the excellent adsorption ability and convenient regeneration make CDP@Fe3O4 being a potential candidate in various complex organic wastewater purification.