Polyol Solvent Research Articles

DPPH scavenging capacity of extracts from Camellia seed dregs using polyol compounds as solvents

This study investigated the properties of extracts of Camellia oleifera Abel seed dregs, which were extracted using polyol compounds. Solvents employed to extract the Camellia seed dregs included water, methanol, ethanol, and polyol compounds. The examined properties included ultraviolet (UV) absorbance, total polyphenol content, total flavonoid content, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging efficiency as an antioxidant ability. The results revealed that the glycerol, glycerol plus ethanol, and propylene glycol plus ethanol solvents yielded extracts with greater DPPH scavenging efficiency and total polyphenol and flavonoid content than the water, methanol, and ethanol solvents did. In addition, the polyol plus ethanol solvents yielded extracts with greater DPPH scavenging efficiency, total polyphenol and flavonoid content, and antioxidant ability than the single polyol solvents did. Furthermore, both the UV and infrared absorption spectra and color reaction test of triterpenoid glycosides revealed that polyol or polyol–ethanol solvents effectively extracted quintessential ingredients such as flavonoids and triterpenoid glycosides and other polyphenols from the Camellia seed dregs. In addition, because polyols are moisture-retaining and nontoxic solvents, the extracts can be directly added to cosmetics after simple filtration. Without the need for solvent separation, C. oleifera Abel dregs extracts exhibit excellent potential for application in products such as body washes, shampoos, hair conditioners, skin care products, cosmetics, and sunscreen lotions.

Tailoring the magnetic properties of cobalt ferrite nanoparticles using the polyol process.

Background: In extrinsically magnetoelectric materials made of two components, the direct magnetoelectric coupling arises from a mechanical strain transmission at the interface due to the shape change of the magnetostrictive component under an external magnetic field. Here, the size of the interface between the two components plays a crucial role. Therefore, the development of nanomaterials exhibiting large surface-to-volume ratios can help to respond to such a requirement. However, the magnetic nanoparticles (NPs) must be highly magnetostrictive and magnetically blocked at room temperature despite their nanometer-size. We describe here the use of the polyol process to synthesize cobalt ferrite (CoxFe3−xO4) nanoparticles with controlled size and composition and the study of the relationship between size and composition and the magnetic behavior.Methods: We used an improved synthesis of magnetostrictive CoxFe3−xO4 NPs based on the forced hydrolysis of metallic salts in a polyol solvent, varying the fraction x. Stoichiometric NPs (x = 1) are expected to be highly magnetostrictive while the sub-stoichiometric NPs (particularly for x ≈ 0.7) are expected to be less magnetostrictive but to present a higher magnetocrystalline anisotropy constant, as previously observed in bulk cobalt ferrites. To control the size of the NPs, in order to overcome the superparamagnetic limit, as well as their chemical composition, in order to get the desired magnetomechanic properties, we carried out the reactions for two nominal precursor contents (x = 1 and 0.67), using two different solvents, i.e., triethylene glycol (TriEG) and tetraethylene glycol (TetEG), and three different durations of refluxing (3, 6 and 15 h). The structure, microstructure and composition of the resulting NPs were then investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray fluorescence spectroscopy (XRF), respectively. The magnetic properties were also evaluated using standard magnetometry. To measure the magnetostrictive response of the particles, the particles were sintered to dense pellets on which strain gauges were bonded, measuring the size variation radially, as a function of a dc magnetic field.Findings: We found two samples, the first one being stoichiometric and magnetostrictive, and the second one being sub-stoichiometric and presenting a higher magnetization, that are appropriate to be used as ferromagnetic building blocks in nanostructured magnetoelectric materials, particularly materials based on polymers. We show that the polyol solvent and the reaction time are two key parameters to control the size and the magnetic properties of the resulting nanoparticles. We believe that these results provide relevant insights to the design of efficient magnetic and magnetostrictive nanoparticles that can be further functionalized by coupling agents, to be contacted with piezoelectric polymers.

Preparation of Sm, Gd and Fe Oxide Nanoparticle-Polydopamine Multicomponent Nanocomposites

Abstract Nanoparticles of samarium(III) oxide (Sm2O3), gadolinium(III) oxide (Gd2O3) and iron(II,III) oxide (Fe3O4), which have different roles in biomedical applications, were synthesized and embedded in biocompatible polydopamine to make them more dispersible, compatible and non-aggregate so as to fully exploit their features in the human body. Herein, the synthesis procedures of the nanoparticles with different sizes and the embedding procedures in polydopamine were investigated in comparison with coating with silica. The particles (60–100 nm diameter) of Sm2O3 and Gd2O3 synthesized by the calcination method were coated by silica shell (80–100 nm thickness) but their dispersibility in water was less. The nanosized particles (4–7 nm) of Sm2O3 and Gd2O3 synthesized by the polyol solvent method were protected by polyol to be dispersed in water. Separately, Fe3O4 nanoparticles (17 nm) were fabricated by co-precipitation reaction. Each nanoparticle was successfully embedded into spheres of polydopamine, although the preparation of composites depended on solvent amount, metal precursor amount and reaction solution pH. The co-embedding of three particles in a polydopamine sphere was also proved by elemental analysis.

The liquid polyol extracts of camellia seed dregs used in sunscreen cosmetics

Polyol solvents were used to extract Camellia oleifera Abel dregs and sunscreen properties of the extracts were examined in the present paper. The effects of extracts obtained with water and ethanol were compared. This study found that polyols were more efficient at extracting flavonoid glycosides, triterpenoid glycosides, and other polyphenols in the C. oleifera Abel dregs, resulting in a more efficient sunscreen. The polyphenols in the extract had peak absorbance at wavelengths of 254, 280, and 329 nm, the triterpenoid glycosides had a peak at 200–240 nm and the flavonoid glycosides showed a broad range of absorption (at 230–400 nm). The extract obtained with polyol solvent had strong absorption at wavelengths of 200–400 nm. The interaction of the polyol extracts with organic UV-absorbers or inorganic sunscreen agents showed synergic effects and the extract can significantly improve the sunscreen effect of organic UV-absorbers or inorganic sunscreen agents. Therefore, this extract can decrease the amount of organic UV-absorbers and inorganic sunscreen agents used and can increase protection against UVA and UVB. It can be used in maintenance and sunscreen products.

Rapid Stepwise Growth of Water-Dispersive CdS Quantum Dots in Ethylene Glycol

Water-dispersive CdS quantum dots (QDs) have been rapidly synthesized in a polyol solvent of ethylene glycol at 160 °C without using nonpolar organic solvents, and their stepwise growth mechanisms ...

아스코빅애씨드 고함량 안정화 수계 조성물 제조 방법

Ascorbic acid (Vitamin C) has been widely used in skin care formulations. Due to its remarkable effects on anti-oxidation, collagen biosynthesis and whitening, ascorbic acid is considered as an effectible anti-aging active ingredient. But, the instability problems of ascorbic acid in cosmetic formulation such as oxidation, browning and changes in smell is the difficult issue to be overcome for the application of high concentration of ascorbic acid. We tried to stabilize the ascorbic acid in non-aqueous liquid formulation that contains polyol solvent at first. The non-aqueous system was effectible to reduce oxidation. But, ascorbic acid was crystallized in the non-aqueous formulation at the low temperature below 5℃. We tried to develop way to stabilize the ascorbic acid in aqueous solutions to solve the crystallizing problem. In this study, we search the optimal ratio of antioxidant combination, such as zinc sulfate, glutathione and curcuma longa (turmeric) root extract. Formulations were stored at - 16℃, 5℃, 25℃, 40℃, 50℃ and cycle(5 – 40℃) (in incubator) for a period of eight weeks to investigate their stability. In the stability analysis, the test parameters consisted of color, scent, phase separation and sedimentation. Ascorbic acid stability was checked by HPLC analysis.

Hybridization of carbon-dots with ZnO nanoparticles of different sizes

Abstract ZnO nanoparticles were hybridized with carbon dots (Cdots) and the hybrids were characterized. ZnO(100) and ZnO(20) with particle sizes of 94 and 20 nm, respectively, were synthesized by calcination and polyol solvent methods, respectively. The morphology, size and crystallinity of ZnO nanoparticles were not varied by the addition of Cdots. The spectroscopic results indicated the successful attachment of Cdots to ZnO nanoparticles. The specific surface area of ZnO(20) was larger than ZnO(100) and increased with the hybridization of Cdots. When the amount of ethylenediamine against citric acid between raw materials of Cdots was increased, the existence of nitrogen in Cdots became recognized. The band gap increased with decreasing particle size, and the addition of Cdots decreased the band gap of ZnO. Thus, these results suggest that the hybrids of ZnO with Cdots may exert the performance on photocatalysis and photovoltaic electrochemistry.

Overcoming the Interfacial Lattice Mismatch: Geometry Control of Gold–Nickel Bimetallic Heteronanostructures

AbstractSeed‐mediated heteroepitaxial growth provides a versatile synthetic approach to a diverse set of geometrically distinct bimetallic heteronanostructures. In bimetallic nanocrystal systems, interfacial heteroepitaxial growth typically occurs between structurally similar metals with lattice mismatch below 5%, whereas controlled epitaxial growth of bimetallic nanocrystals comprising metals with larger lattice mismatches or even dissimilar crystalline structures has long been challenging. Here, the epitaxial growth of both face‐centered cubic (fcc) and hexagonal close‐packed (hcp) Ni on fcc Au nanocrystal seeds in polyol solvents is systematically investigated, to shed light on the complex mechanisms underpinning the intriguing geometric evolution of lattice‐mismatched bimetallic nanocrystals during seed‐mediated heteroepitaxial overgrowth. The success in geometry‐controlled syntheses of a series of Au–Ni bimetallic heteronanostructures, such as conformal core–shell nanoparticles, asymmetric heterodimers, and multibranched core–satellite nanocrystals, represents a significant step toward the extension of nanoscale interfacial heteroepitaxy from lattice‐matched bimetallic systems to the ones exhibiting large lattice mismatches and even dissimilar crystalline structures. The insights gained from this work serve as a central design principle that guides the development of new synthetic approaches to architecturally sophisticated and compositionally diverse multimetallic heteronanostructures.

Dy2O3/CuO nanocomposites: microwave assisted synthesis and investigated photocatalytic properties

Dy2O3/CuO nanocomposites were synthesized by rapid and fast microwave method in polyol solvent. Effect of time and power of microwave irradiation and type of solvent on size and morphology were investigated. Synthesized Dy2O3/CuO is characterized with X-ray diffraction (XRD) analysis, Transmission Electron Microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) and UV–Visible absorption spectroscopy. Photocatalytic properties for two color, methylene blue and rhodamin b under ultraviolet light irradiation were done and 54 and 47.7% degradation for MB and RB respectively.

Tuning Sizes, Morphologies, and Magnetic Properties of Monocore Versus Multicore Iron Oxide Nanoparticles through the Controlled Addition of Water in the Polyol Synthesis.

The polyol route is a versatile and up-scalable method to produce large batches of iron oxide nanoparticles with well-defined structures and magnetic properties. Importance of parameters such as temperature and reaction time, heating profile, nature of the polyol solvent or organometallic precursors on nanostructure and properties has already been described in the literature. Yet, the crucial role of water in the forced hydrolysis pathway has never been reported, despite its mandatory presence for nanoparticle production. This communication investigates the influence of the water amount and temperature at which it is injected in the reflux system for either a pure polyol solvent system or a mixture with poly(hydroxy)amine. Distinct morphologies of nanoparticles were thereby obtained, from ultra-ultra-small smooth spheres down to 4 nm in diameter to larger ones up to 37 nm. Well-defined multicore assemblies with narrow grain size dispersity termed nanoflowers were also synthesized. A diverse and large library of samples was obtained by manipulating the nature of solvents and the amount of added water while keeping all other parameters constant. The different morphologies lead to magnetic nanoparticles suitable for important biomedical applications such as magnetic hyperthermia, magnetic resonance imaging (MRI) contrast agent, or both.

Electrical properties and aquatic ecotoxicity effects of ZnS nanocrystals

A new synthesis method of ZnS colloidal nanocrystals is presented in this work, and this novel approach allows one to produce Zinc sulfide nanocrystals owing to a modified polyol process that makes use of 1.3-propanediol as a solvent. The structure and morphology of the nanoparticles were characterized by high-resolution transmission electron microscopy, transmission electron microscopy, X-ray diffraction and spectroscopy photoluminescence. The results showed that quasi-spherical ZnS nanocrystals with sizes in the range 3–5 nm were formed. Their morphology, size and colloidal stability are driven by the polyol solvent. Under UV excitation, a strong visible PL emission, due to the radiative recombinations of the electron–hole pairs photo-generated in the ZnS nanoparticles, was observed. In order to study the environmental risk of ZnS, mussels Mytilus galloprovincialis were exposed to ZnS C1 $$=$$ 0.1 mg/L, ZnS C2 $$=$$ 1 mg/L and ZnS C3 $$=$$ 10 mg/L. Superoxide dismutase, catalase activities and protein thiols density were determined in the gill of treated and untreated mussels. No significant effects were detected in the gills of exposed mussels after 14 days of exposure compared to control. Optical property of the new nanomaterial, together with the easy synthesis process, makes the ZnS nanocrystals a promising candidate for applications optoelectronics and photocatalyst. The frequency-dependent impedance and AC conductivity have been investigated in this context. Impedance and modulus plane plots from 10 to $$10^{7}$$ Hz show the presence of bulk and grain boundary phases in ZnS at each measurement temperature from 125 to $$225\,^{\circ }\hbox {C}$$ . The activation energy was calculated from the temperature variation of DC conductivity. Studies of frequency and temperature dependence of electrical data of the compound suggest that conduction process in the material is thermally activated. Environmental risk assessment results constitute a scientific support for considering the use of this nonmaterial on various applications after further complementary studies in order to ensure the safety of these NPs.

Nano-sized CuO/ZnO hollow spheres: synthesis, characterization and photocatalytic performance

CuO/ZnO hallow spherical nanocomposite were synthesis with rapid microwave method in polyol solvent at 10 min and 900 W as optimum time and power. Prepared CuO/ZnO is characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and for an estimate the band gap used diffuse reflectance measurement. For the sufficient optical properties, prepared CuO/ZnO nanocomposites are applied as a catalyst in photodegradation of rhodamine B (RB) and methylene blue (MB) pollutants. Results showed that after 120 min, 41 and 73% of RB and MB was degraded respectively.

Surface Modification and Heat Generation of FePt Nanoparticles.

The chemical reduction of ferric acetylacetonate (Fe(acac)3) and platinum acetylacetonate (Pt(acac)2) using the polyol solvent of phenyl ether as an agent as well as an effective surfactant has successfully yielded monodispersive FePt nanoparticles (NPs) with a hydrophobic ligand and a size of approximately 3.8 nm. The present FePt NPs synthesized using oleic acid and oleylamine as the stabilizers under identical conditions were achieved with a simple method. The surface modification of FePt NPs by using mercaptoacetic acid (thiol) as a phase transfer reagent through ligand exchange turned the NPs hydrophilic, and the FePt NPs were water-dispersible. The hydrophilic NPs indicated slight agglomeration which was observed by transmission electron microscopy images. The thiol functional group bond to the FePt atoms of the surface was confirmed by Fourier transform infrared spectroscopy (FTIR) spectra. The water-dispersible FePt NPs employed as a heating agent could reach the requirement of biocompatibility and produce a sufficient heat response of 45 °C for magnetically induced hyperthermia in tumor treatment fields.

Synthesis of Mono-Dispersed Olive-Shaped LiFePO4 Nanoparticles By Polyol Method

Since the use of olivine-structured lithium iron phosphate (LiFePO4, LFP) as a cathode material for rechargeable lithium batteries was first reported by Goodenough and co-workers in 1997, LFP has been extensively and intensively studied, owing to its significant advantages including high theoretical capacity (170 mAhg-1), long cycle life(≥2000), acceptable operating voltage (3.4V vs. Li+/Li), environmental benignity, high safety, and low cost. Unfortunately, LFP possesses a major drawback in its sluggish kinetics of electron and lithium-ion transport, which restricts its rate performance. To date, many studies have been made to reduce the particle size and incorporate carbon additives of LFP, so as to improve the electronic conductivity and thus enhance the diffusion of Li ions across the LFP/FePO4 interface. Many techniques have been developed to synthesize nanosized LFP with uniform size distributions, which include the hydrothermal method, polyol and solvothermal methods, sol-gel methods, reverse micelle process and spray pyrolysis. Among them, the polyol method is considered one of the most facile and efficient methods to synthesize nanosize LFP with high crystallinity. Therefore, in this study, we would like to control the size, crystallization degree, morphology of LFP particles via a facile, low temperature polyol method to improve its ionic and electric transport properties. In this method, the polyol solvent (ethylene glycol) could generate a reductive atmosphere even in the absence of any reductive agent. Highly-dispersed LFP cathode nanospheres with olive-shape was synthesized by a simple polyol refluxing process without any post heat treatments. As-obtained samples were characterized by XRD, FE-SEM, TEM, BET etc. As confirmed by these characterization results that olive-like LFP nanoparticles with high crystallization degree were successfully prepared in this study. And the sizes of these nano/micro-particles are ranged from 50 nm to 800 nm. The various processing parameters, namely, reaction temperature and material ratio, have been varied, and the effects on the growth of LFP particles have been analyzed systematically to optimize the preparation condition. Finally, the electrochemical properties especially the rate performance of as-resulted LFP nanoparticles, employing the reported as comparison, were discussed, which is the key point of their application in Li ion batteries. Figure 1

An Aerobic Alternative to Oxidative Ozonolysis of Styrenes

AbstractA general, selective and extremely efficient procedure for the aerobic cleavage of aromatic alkenes is presented. TON values in the range 6,000,000–10,000,000 are obtained for this nickel‐catalyzed reaction performed in polyethylene glycol 400 under 1 atm of molecular oxygen. Mono‐, di‐, tri‐ and tetrasubstituted styrene derivatives are oxidatively cleaved by this reproducible protocol, also suitable for larger scale (1.5 g) reactions. The presence of several functional groups (alkyl, alkoxy, halogen, trifluoromethyl) is tolerated in the substrates. The mechanistic proposal to explain the selective generation of carboxylic acids and ketones from aromatic alkenes involves the participation of the polyol solvent in the presented oxidative process.magnified image

Solvothermal synthesis of carbon nanotube-AgBiS2 hybrids and their optical limiting properties

AgBiS2 nanoparticles (NPs) have been loaded on multiwalled carbon nanotubes (MWCNTs) by the solvothermal treatment on a mixture of MWCNTs, AgNO3, Bi(NO3)3·5H2O and thiosemicarbazide in a mixed polyol solvent. The resulting MWCNT-AgBiS2 hybrid samples have been extensively characterized by a variety of microscopic and spectroscopic techniques. The AgBiS2 NPs can be uniformly deposited on the sidewalls of MWCNTs by appropriately regulating the reaction conditions including reaction temperature and reaction time. Optical limiting (OL) studies have been performed on typical MWCNT-AgBiS2 samples using the Z-scan and OL measurements at the laser wavelength of 532nm. The MWCNT-AgBiS2 hybrids with AgBiS2 NPs of ∼16nm in size uniformly coated on the nanotubes show a significantly enhanced OL effect in comparison to the purified MWCNTs.

Studies on graphene enfolded olivine composite electrode material via polyol technique for high rate performance lithium-ion batteries

The graphene enfolded LiFePO4/C composite cathode material has been prepared via low temperature polyol process, followed by a simple chemical reaction method. The low viscous polyol solvent (DEG) (35.7 mPa s at 25°C) and usage of low temperature process (below 245°C) aid the graphene tightly encapsulated on the LiFePO4 surface that plays an important role, especially in the high rate performances over long cycles, efficiently preventing the separation of the graphene and LiFePO4 during the reaction processes, hence realizing the full potential of the active materials. The graphitization on LiFePO4/C remarkably increased the electronic conductivity of LiFePO4. The layered sheets of graphene wrapped on LiFePO4 particles provide void between graphene sheets and LiFePO4 surfaces, which facilitate the diffusion of Li+. This approach opens up a method to attain the theoretical capacity of LiFePO4. The material exhibits a superior electrochemical performance such as initial discharge capacities of 169.6 and 92 mAhg−1 at 0.1 and 30 C rates, respectively. It has an excellent capacity retention and diminutive capacity fading. The nanosize of LiFePO4 particle causes a shorter diffusion path, which reduces the time for Li+ migration between cathode and electrolyte.

Simple fabrication of Ag nanoparticle-impregnated electrospun nanofibres as SERS substrates

A facile method for the fabrication of electrospun polyurethane (PU) nanofibres impregnated with Ag nanoparticles (NPs) as an efficient and free-standing surface-enhanced Raman scattering (SERS) substrates is reported here. Electrospinning was used to produce polymeric nanofibrous matrix, while a liquid polyol(ethylene glycol) solvent under low temperature was used not only to reduce Ag+ to Ag 0, but also was employed as the in situ growth medium for well-dispersed Ag NPs on the surface of fibre nets. Large enhancement in Raman signals of 4-mercaptobenzoic acid analytes could be realized in the present Ag/PU nanofibres due to the presence of SERS ‘hotspots’ by means of appropriate interparticle gap.

Study of antibacterial activity of Ag and Ag2CO3 nanoparticles stabilized over montmorillonite

Silver carbonate and silver nanoparticles (NPs) over of stabilizer montmorillonite (MMT) have been synthesized in aqueous and polyol solvent, respectively. Dispersions of silver nanoparticles have been prepared by the reduction of silver nitrate over of MMT in presence and absence of Na2CO3 compound in ethylene glycol. It was observed that montmorillonite was capable of stabilizing formed Ag nanoparticles through the reduction of Ag+ ions in ethylene glycol. Na2CO3 was used as carbonate source in synthesis of Ag2CO3 NPs in water solvent and also for controlling of Ag nanoparticles size in ethylene glycol medium. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and ultraviolet–visible diffuse reflectance spectroscopy (DRS). The TEM images showed that Ag NPs size in presence Na2CO3 salts was smaller than without that. The results indicated intercalation of Ag and Ag2CO3 nanoparticles into the montmorillonite clay layers. The diffuse reflectance spectra exhibited a strong surface plasmon resonance (SPR) adsorption peak in the visible region, resulting from Ag nanoparticles. The antibacterial testing results showed that the Ag2CO3-MMT nanocomposite exhibited an antibacterial activity higher than Ag-MMT sample against Escherichia coli.

Granular Fe3 − xO4-CoO hetero-nanostructures produced by in situ seed mediated growth in polyol: magnetic properties and chemical stability

We report here the synthesis of granular composites based on intimately mixed ferrimagnetic Fe3 − xO4 and antiferromagnetic CoO nanocrystals using forced hydrolysis in a polyol solvent. Typically, 10 nm sized iron oxide nanoparticles were pre-formed in diethyleneglycol and used as seeds to grow epitaxially cobalt monoxide nanocrystals, in the same reaction mixture. X-ray diffraction, transmission electron microscopy, 57Fe Mössbauer spectrometry and dc-magnetometry confirmed the production of the desired hetero-nanostructures, of great interest in the field of magnetic recording, and evidenced the formation of a kind of cobalt ferrite solid solution between the initially formed Fe3 − xO4 and latterly deposited CoO nanocrystals. The resulting Co and Fe concentration gradient significantly affects the low temperature magnetization reversal of the composite nanostructures compared to the pristine iron oxide magnetite-like powder. Moreover, with time, air exposure leads to an almost total transformation of the CoO phase into Co3O4 and the electronic displacement of a great part of the Fe2+ ions into Fe3+ ones in the whole grain volume, along with noteworthy low temperature magnetization and coercivity decrease. This material evolution makes the studied composites less valuable for most of the magnetic based functional applications and underlines the importance to pay attention to their storage and integration into functional devices before use.