2-methoxyethanol Research Articles

Synthesis and Photo-Response of CuS Thin Films by an In Situ Multi-Deposition Process at Room Temperature: A Facile and Eco-Friendly Approach

Uniform hexagonal covellite CuS thin films were deposited at room temperature by an in situ solution chemical reaction using copper precursor solid films as cationic source and ammonium sulfide ethanol solution as anionic reaction medium. We investigated the influence of both ethanolamine and butanol contents used in copper nitrate/ethylene glycol monomethylether (EGME) cationic solution for the preparation of copper precursor solid films, deposition cycle numbers and annealing treatment of the as-grown thin films by X-ray diffraction (XRD), FESEM, energy dispersive X-ray fluorescence EDX, transmission electron microscopy–Selected area electronic diffraction (TEM–SAED), atomic force microscopy (AFM) and ultraviolet-visible-near-infrared (UV-Vis–NIR) measurements. Photo-response of the CuS thin films was characterized by linear sweep voltammetry. The deposited CuS thin films were used to sensitize TiO 2 anodes for solar cell application. The results showed that the CuS films had two-dimension oriented, half-sheet shaped growing morphology standing disorderly but vertically to substrates, and the calculated texture coefficient TC(102) verified that the half-sheet shaped crystallites had (102) plane orientation. This in situ multi-deposition process had an average deposited rate of 9 nm per cycle, and a self-perfect function to grow smooth, uniform and 2D oriented morphology with increase in the dip-cycle numbers. The photocurrent density was 14.5 Ma/cm2 at 1 V versus Ag / AgCl electrode for the annealed CuS thin films. CuS -sensitized TiO 2 solar cells had a maximum conversion efficiency of 0.224%.

Structural and optical properties of ZnO thin films deposited by sol–gel method: effect of stabilizer concentration

Nanocrystalline thin films of ZnO were successfully deposited on Si substrate via sol–gel method using zinc acetate dehydrate as a precursor and 2-methoxy ethanol as a solvent. The effect of stabilizer concentration on the structural and optical properties of the ZnO thin film was investigated as the stabilizer concentration affects the growth orientation of ZnO thin films prepared by sol–gel method. The growth in (002) plane of hexagonal structure is preferred in many applications as the 2-dimensional Zn atoms population is highest in this orientation. The growth of (002)-oriented ZnO films was optimized with the concentration of the stabilizer (triethanolamine). The crystal structures of the samples were analyzed using X-ray diffractometer confirming the polycrystalline nature and hexagonal structure of films. In order to estimate the preferential crystallite orientation quantitatively, the texture coefficient (Tc) was calculated. The particle size and strain was also found to change with concentration of stabilizer. SEM results confirm the formation of nanocrystalline thin films with homogeneous morphology. Photoluminescence characteristics show a direct band gap transition which shifts towards lower wavelength with increase in stabilizer concentration. It was observed that the stabilizer concentration is the most important factor to grow a highly (002)-oriented ZnO film along c-axis.

NMR studies of the equilibria and reaction rates in aqueous solutions of formaldehyde.

Formaldehyde has an important role in the chemical industry and in biological sciences. In dilute aqueous solutions of formaldehyde only traces of the molecular formaldehyde are present and the predominant species are methylene glycol and in lower concentrations, dimethylene glycol. The chemical equilibria and reaction rates of the hydration of formaldehyde in H2O and D2O solutions at low concentrations were studied by (1)H and (13)C NMR at various conditions of pH (1.8-7.8) and temperature (278-333 K). These measurements became possible by direct detection of formaldehyde (13)C and (1)H peaks. The equilibrium and rate constants of the dimerization reaction of methylene glycol were also measured. The rate constants for both the hydration and the dimerization reactions were measured by a new version of the conventional selective inversion transfer method. This study, together with previous published work, completes the description of dynamics and equilibria of all the processes occurring in dilute aqueous formaldehyde solutions.

New insight into the kinetics of diisocyanate‐alcohol reactions by high‐performance liquid chromatography and mass spectrometry

ABSTRACTThe uncatalyzed reactions of 2,4‐TDI (2,4‐toluenediisocyanate) and MDI (4,4′‐diphenylmethane‐diisocyanate) with alcohols including butan‐1‐ol, butan‐2‐ol, diethylene glycol monomethylether (DEGME) were studied by high‐performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI‐MS). The reactions were carried out at different temperatures from 22°C to 75°C using high molar ratios of alcohols to diisocyanates. It was found that the first isocyanate group of the MDI reacts about 1.5 times faster with the alcohols than the second one. The relative reactivities of the isocyanate groups (para and ortho) of 2,4‐TDI as a function of the temperature was also deduced. From the temperature dependence of the rate constants the apparent activation energies were determined. Furthermore, the dependence of the apparent rate constant on the concentration of alcohols was also investigated and a mechanism was proposed for the reaction of diisocyanates with alcohols. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42127.

Facile preparation of biocompatible and robust fluorescent polymeric nanoparticles via PEGylation and cross-linking.

Novel cross-linked copolymers of PEG-IM-PhNH2 are successfully synthesized through PEGylation via radical polymerization of 2-isocyanatoethyl methacrylate and poly(ethylene glycol) monomethyl ether methacylate and subsequent cross-linking with an amino-terminated aggregation-induced emission fluorogen. Such obtained amphiphilic copolymers can self-assemble to form uniform fluorescent polymeric nanoparticles (FPNs) and be utilized for cell imaging. These cross-linked FPNs are demonstrated good water dispersibility with ultralow critical micelle concentration (∼ 0.002 mg mL(-1)), uniform morphology (98 ± 2 nm), high red fluorescence quantum yield, and excellent biocompatibility. More importantly, this novel strategy of fabricating cross-linked FPNs paves the way to the future development of more robust and biocompatible fluorescent bioprobes.

Functionalized multiwalled carbon nanotubes as reinforcing agents for poly(vinyl alcohol) and poly(vinyl alcohol)/starch nanocomposites: synthesis, characterization and properties

AbstractThis paper describes the synthesis and characterization of poly(vinyl alcohol) (PVA) and PVA/starch nanocomposites with poly(ethylene glycol)‐functionalized multiwalled carbon nanotubes (MWCNTs‐PEG). For this purpose, MWCNTs were carboxylated by a conventional acid oxidation process and then poly(ethylene glycol) monomethylether was covalently attached to the carboxylated MWCNTs via esterification. Sonication was used to assist the dispersion of MWCNTs‐PEG and the resulting suspension was added dropwise to a stirred aqueous solution of poly(ethylene glycol) and PVA/starch to produce PVA/MWCNTs‐PEG and PVA/starch/MWCNTs‐PEG nanocomposites. The chemical structures of all samples as representatives were characterized by Fourier transform infrared spectroscopy and the morphology of the nanocomposites was probed by scanning electron microscopy. Moreover, it was observed that the mechanical properties of the nanocomposites were improved due to presence of functionalized MWCNTs. © 2015 Society of Chemical Industry

MicroRNA profling in ethylene glycol monomethyl ether-induced monkey testicular toxicity model

To establish and characterize ethylene glycol monomethyl ether (EGME)-induced testicular toxicity model in cynomolgus monkeys, EGME at 0 or 300 mg/kg was administered orally to sexually mature male cynomolgus monkeys (n = 3/group) for 4 consecutive days. Circulating and testicular microRNA (miRNA) profiles in this model were investigated using miRNA microarray or real-time quantitative reverse transcription-PCR methods. EGME at 300 mg/kg induced testicular toxicity in all the monkeys, which was characterized histopathologically by decreases in pachytene spermatocytes and round spermatids, without any severe changes in general conditions or clinical pathology. In microarray analysis, 16 down-regulated and 347 up-regulated miRNAs were detected in the testis, and 326 down-regulated but no up-regulated miRNAs were detected in plasma. Interestingly, miR-1228 and miR-2861 were identified as abundant miRNAs in plasma and the testis of control animals, associated presumably with apoptosis and cell differentiation, respectively, and were prominently increased in the testis of EGME-treated animals, reflecting the recovery from EGME-induced testicular damages via stimulating cell proliferation and differentiation of sperm. Furthermore, down-regulation of miR-34b-5p and miR-449a, which are enriched in meiotic cells like pachytene spermatocytes, was obvious in the testis, suggesting that these spermatogenic cells were damaged by the EGME treatment. In conclusion, EGME-induced testicular toxicity in cynomolgus monkeys was shown, and this model would be useful for investigating the mechanism of EGME-induced testicular toxicity and identifying testicular biomarkers. Additionally, testicular miR-34b-5p and miR-449a were suggested to be involved in damage of pachytene spermatocytes.

Degradable polymeric nanoparticles by aggregation of thermoresponsive polymers and "click" chemistry.

This study describes a novel approach to the preparation of crosslinked polymeric nanoparticles of controlled sizes that can be degraded under basic conditions. For this purpose thermoresponsive copolymers containing azide and alkyne functions were obtained by ATRP of di(ethylene glycol) monomethyl ether methacrylate (D) and 2-aminoethyl methacrylate (A) followed by post polymerization modification. The amino groups of A were reacted with propargyl chloroformate or 2-azido-1,3-dimethylimidazolinium hexafluorophosphate, which led to two types of copolymers. Increasing the temperature of aqueous solutions of the mixed copolymers caused their aggregation into spherical nanoparticles composed of both types of chains. Their dimensions could be controlled by changing the concentration and heating rate of the solutions. Covalent stabilization of aggregated chains was performed by a "click" reaction between the azide and alkyne groups. Due to the presence of a carbamate bond the nanoparticles undergo pH dependent degradation under mild basic conditions. The proposed procedure opens a route to new carriers for the controlled release of active species.

Methyl glycol, methanol and DMSO effects on post-thaw motility, velocities, membrane integrity and mitochondrial function of Brycon orbignyanus and Prochilodus lineatus (Characiformes) sperm

The aim of this study was to use more accurate techniques to investigate the effects of cryoprotectants (CPAs) and extenders on post-thaw sperm quality of Brycon orbignyanus and Prochilodus lineatus. Six freezing media comprising the combination of three CPAs (DMSO, methanol and methyl glycol) and two extenders (BTS and glucose) were used. Sperm was diluted in each medium, loaded into 0.5-mL straws, frozen in a nitrogen vapor vessel (dry-shipper), and stored in liquid nitrogen at -196 °C. Post-thaw sperm motility rate and velocities (curvilinear = VCL; straight line = VSL; average path = VAP) were evaluated using a computer-assisted sperm analyzer. Membrane integrity and mitochondrial function were determined using fluorochromes. Post-thaw quality was considered high when samples presented the following minimum values: 60 % motile sperm, 140 µm/s of VCL, 50 % intact sperm membrane and 50 % mitochondrial function integrity. High post-thaw quality was observed in B. orbignyanus sperm frozen in BTS-methyl glycol and in P. lineatus sperm frozen in BTS-methyl glycol, glucose-methyl glycol and glucose-methanol. All samples frozen in DMSO yielded low quality. The presence of ions in the BTS extender affected post-thaw sperm quality positively in B. orbignyanus and negatively in P. lineatus. Methyl glycol was the most suitable CPA for both fish species, leading to a good protection of cell membrane, mitochondrial function and motility apparatus during the cryopreservation process. For an improved protection, B. orbignyanus sperm should be frozen in an ionic freezing medium.

Facile fabrication of carbon spheres with tunable morphologies from novel polymeric carbon precursors.

This study presents a facile and general method for fabrication of carbon spheres with tunable morphologies based on the sol-gel reaction of a novel polymeric carbon precursor. The carbon precursor was fabricated by the synthesis of resole, a low-molecular weight polymer of phenol and formaldehyde, and then the modification with poly(ethylene glycol) monomethyl ether (PEG). By turning the modification degree of resole with different amounts of PEG and the hydrolysis and condensation reactions of this precursor, carbon spheres with various morphologies, including regular spheres, hollow spheres of different pore sizes, and raspberry- and peanut-like spheres, were produced easily. This should be attributed to the condensation, self-assembly, and phase separation of the new polymeric carbon precursors during the sol-gel process.

Tailored thiol-functional polyamides: synthesis and functionalization.

In this article, a synthetic concept for the preparation of polyamides with functional side groups is described. First, the synthesis of a bis(thiolactone) monomer is shown in a concise three-step route from itaconic acid and DL-homocysteine thiolactone. The reactivity of the resulting bis(thiolactone) toward hexyl amine is examined. Next, the bis(thiolactone) is reacted as A,A-type monomer with different B,B-type comonomers (1,12-diaminododecane and 1,3-bis(aminopropyl)tetramethyldisiloxane). Ring opening of the thiolactones by the diamines leads to polyamides with pendant thiol groups. Using two diamines in different ratios, the properties of the resulting polyamides are tuned (thermal properties are determined) and different molecular weights are acquired. Subsequently, the thiol groups are reacted with methyl acrylate via Michael addition to functionalize the polyamides. Functionalization of thiol-functional polyamides using poly(ethylene glycol) monomethyl ether (mPEG) acrylates (Mn = 480 and 1700 g mol(-1) ) results in water-soluble amphiphilic poly-amides with molecular weights higher than 10,000 g mol(-1) .

Reactive polymeric micelles with disulfide groups in the coronae

Micelles self-assembled by block copolymers are widely used in nanoscience and biomedical science. In the past few decades, much effort has been applied to the synthesis, characterization and applications of the polymeric micelles. However, previous research studies have paid less attention to the functionalization of coronae of the micelles. Herein, micelles with disulfide groups in the coronae were prepared and the micelles were used as a platform for functional modification reactions. Polystyrene-block-poly(oligo(ethylene glycol)monomethyl ether methacrylate)-block-poly(oligo(ethylene glycol)monomethyl ether methacrylate-co-2-((2-hydroxyethyl)disulfanyl)ethyl methacrylate), PS-b-PPEGMA-b-P(PEGMA-co-HDSMA), triblock copolymer was synthesized by RAFT polymerization. In aqueous solution, the triblock copolymer self-assembled into micelles with disulfides in the coronae. Upon cleavage of the disulfide bonds, thiol groups were produced in the coronae, and the micelles were able to undergo oxidation-induced aggregation. Hydroethyl disulfide groups in the PS-b-PPEGMA-b-P(PEGMA-co-HDSMA) triblock copolymer were converted to pyridyl disulfide groups by cleavage of the S–S bonds with tributylphosphine and reaction with dipyridyl disulfide. In PBS buffer solution, the modified triblock copolymer self-assembled into micelles with pyridyl disulfides in the coronae. The micelles were used as a platform for the preparation of glutathione or fluorescent group-decorated micelles. The antioxidant properties and the fluorescence properties of the functional micelles are reported in this paper. On the basis of this method, many different functional micelles can be prepared.

Dimerization of methylene blue in aqueous and mixed aqueous organic solvent: A spectroscopic study

The dimerization of methylene blue (MB) dye in aqueous and mixed aqueous organic solvents has been investigated spectrophotometrically at 303.15K. The organic solvents chosen for the study include ethylene glycol, 2-methoxy ethanol, 2-ethoxy ethanol, tetrahydrofuran and dioxane. The dimerization constant KD of MB in aqueous as well as the mixed aqueous media has been computed from their UV–visible spectra. Addition of the organic solvent of low dielectric constant resulted into lowering of the KD perhaps due to the overall decrease in dielectric constant of mixed media. However, decrease in KD in the mixed media was not in order of decreasing dielectric constant of the mixed media. In fact, introduction of hydrophobic methyl or ethyl group in ethylene glycol led to an increase in KD in the order 2-ethoxy ethanol>2-methoxy ethanol>ethylene glycol even though the dielectric constant of ethylene glycol is higher than that of methyl or ethyl substituted ethylene glycol. The change in the fraction of monomeric dye (α) in the presence of the mixed aqueous organic solvent as a function of the dye concentration has also been computed. The spectra for the monomer and the dimer species of MB have been re-constructed using the KD values and the results have been analysed in the light of the molecular exciton theory. Both the twist (θ1) and the tilt (θ2) angles between the transition dipoles of the MB molecules in the dimer have been computed. It was observed that the presence of the organic solvent led to decreasing not only the twist but also the tilt angle. The results indicated that the dimer essentially has sandwich geometry with a slight deviation from the exact parallel stacking arrangement of the dye molecular planes highlighting the importance of dispersive forces including the hydrophobic effects in the formation of the dye aggregates.

Modeling of Micelle-Solution Equilibria for Mixed Nonionic Micelles with Strong Specific Interactions in Coronae: Group-Contribution Approach

A molecular thermodynamic model of micellization is proposed that takes into account strong specific interactions in the mixed micelle and hydration in micellar corona. To describe local interactions between molecular segments in the micelle we employ a quasichemical group contribution model of the bulk phase. “Segments-and-bonds” formalism is applied and correction for the connectivity of molecular chains is derived for the chemical potential in quasichemical approximation. The proposed general method may be used in combination with other bulk phase models, particularly with SAFT. The new method is applied to describe (1) the equilibrium distribution of alkanols between the N-dodecanoyl-methyl-glucamine micelle and dilute aqueous solution, and (2) the free energies of transfer of m-ethylene glycol mono-n-alkyl ether surfactants from aqueous solution to the micelles. Comparison with experiment shows the robustness of our approach.

Thermodynamics of solvation in propylene glycol and methyl cellosolve

Limiting activity coefficients of low-polar substances: aliphatic and aromatic hydrocarbons, including alkanes, cycloalkanes, alkylbenzenes, and halobenzenes in two solvents, propylene glycol and methyl cellosolve, were measured at temperature T=298.15K using gas chromatographic headspace analysis technique. The Gibbs free energies of solvation were calculated from these data and analyzed together with the enthalpies of solvation for the same systems. It was shown that the Gibbs free energies of solvation in propylene glycol are significantly lower than in its homologue ethylene glycol, and in methyl cellosolve they are lower than in propylene glycol. This difference is mainly due to the solvophobic effect, which strength is decreasing in the same order: ethylene glycol>propylene glycol>methyl cellosolve. The contribution of the solvophobic effect into the Gibbs free energies of solvation can be determined using a Gibbs free energy versus enthalpy of solvation plot. This contribution is shown to grow up linearly with the molecular volume of a solute in propylene glycol and methyl cellosolve, as well as in ethylene glycol and in monohydric alcohols.

Stable biocompatible cross-linked fluorescent polymeric nanoparticles based on AIE dye and itaconic anhydride

Self-assembly of polymeric materials to form nanoparticles is a particularly promising strategy for various biomedical applications, however, these self-assembling systems often encounter the critical micelle concentration (CMC) issue, as the nanoparticles is usually unstable at low concentration. Therefore, stable cross-linked fluorescent polymeric nanoparticles (FPNs) were covalently constructed from an aggregation induced emission (AIE) dye, itaconic anhydride, poly(ethylene glycol) monomethyl ether methacylate and polyethylenimine. These obtained PhE-ITA-20%(80%) FPNs were fully characterized by a series of techniques including 1H NMR spectra, UV–vis absorption spectra, fluorescence spectra, FT-IR spectra, transmission electron microscopy, gel permeation chromatography, and dynamic light scattering. Such FPNs emitted intense fluorescence due to the introduction of aggregation induced emission dye. More importantly, the FPNs were found extremely stable in physiological solution even below the CMC owing to their cross-linked architectures. Biocompatibility evaluation and cell uptake behavior of the FPNs were further investigated to explore their potential biomedical applications, the demonstrated excellent biocompatibility made them promising for cell imaging.

Calorimetric study of solvation of low polar solutes in propylene glycol and methyl cellosolve at 298 K

Enthalpies of solution of low-polar substances: aliphatic and aromatic hydrocarbons, including alkanes, cycloalkanes, alkylbenzenes, and halobenzenes in two solvents, propylene glycol and methyl cellosolve, were measured at temperature T = 298.15 K using titration calorimetry. In addition, the enthalpies of solution of poorly soluble solid solutes, naphthalene and biphenyl, in these solvents were determined using indirect method by measuring the enthalpies of solution of liquid mixtures containing them. The enthalpies of solvation from the gas phase were calculated from these data. The enthalpies of solvation in propylene glycol and methyl cellosolve and previously reported enthalpies of solvation in ethylene glycol were correlated with each other and with molecular parameters of solutes.

Effects of ethylene glycol monomethyl ether and its metabolite, 2-methoxyacetic acid, on organogenesis stage mouse limbs in vitro.

Exposure to ethylene glycol monomethyl ether (EGME), a glycol ether compound found in numerous industrial products, or to its active metabolite, 2-methoxyacetic acid (2-MAA), increases the incidence of developmental defects. Using an in vitro limb bud culture system, we tested the hypothesis that the effects of EGME on limb development are mediated by 2-MAA-induced alterations in acetylation programming. Murine gestation day 12 embryonic forelimbs were exposed to 3, 10, or 30 mM EGME or 2-MAA in culture for 6 days to examine effects on limb morphology; limbs were cultured for 1 to 24 hr to monitor effects on the acetylation of histones (H3K9 and H4K12), a nonhistone protein, p53 (p53K379), and markers for cell cycle arrest (p21) and apoptosis (cleaved caspase-3). EGME had little effect on limb morphology and no significant effects on the acetylation of histones or p53 or on biomarkers for cell cycle arrest or apoptosis. In contrast, 2-MAA exposure resulted in a significant concentration-dependent increase in limb abnormalities. 2-MAA induced the hyperacetylation of histones H3K9Ac and H4K12Ac at all concentrations tested (3, 10, and 30 mM). Exposure to 10 or 30 mM 2-MAA significantly increased acetylation of p53 at K379, p21 expression, and caspase-3 cleavage. Thus, 2-MAA, the proximate metabolite of EGME, disrupts limb development in vitro, modifies acetylation programming, and induces biomarkers of cell cycle arrest and apoptosis

Influence of Nonionic Rosin Surfactants on Surface Activity of Silica Particles and Stability of Oil in Water Emulsions

AbstractRosin as a natural product has become a source for production of less toxic bio‐surfactants to produce emulsions which are widely used in various agriculture and food products, cosmetic, and pharmaceutical industries. In this respect, a nonionic surfactant was prepared from reaction of rosin acids and rosin maleic anhydride adduct with poly(ethylene glycol) monomethyl ether 750 (MPEG 750) to produce a rosin ester (RMPEG 750). The surface activity parameters of the prepared surfactants, such as surface excess concentration (Γmax), the area per molecule at interface (Amin), and the effectiveness of surface tension reduction, were measured to determine the micellization and adsorption characteristics of the prepared surfactants at the water/air interface. The adsorption of the prepared surfactants on the surface of either hydrophilic or hydrophobic silica particles was determined using a spectrophotometric method. Interfacial tension between water and toluene were measured to select the best condition to obtain toluene/water emulsion in the presence of modified solid silica particles. The effects of silica particle hydrophilicity and the surfactant concentrations on the surface, interfacial activity, and on the emulsion drop size were also investigated.

Effect of ethylene glycol monomethyl ether ratio in mixed solvent on surface morphology, wettability and photocatalytic properties of ZnO thin films

Zinc oxide (ZnO) thin films with different ethylene glycol monomethyl ether (EGME) ratio were prepared on Si substrates using a two-step process. The results show that they possess a polycrystalline hexagonal wurtzite crystal structure. The topography of the ZnO thin films evolves from nanoparticles to hexagonal nanorods with the decrease of EGME content. The photoluminescence spectra consist of a near-band-edge emission and two visible emissions. The optical band gap energy decreases first and then increases with the increase of EGME ratio in mixed solvent, the broadening of the optical band gap can be explained by Moss–Burstein effect. The wetting behavior of all the samples can switch from hydrophobicity to hydrophilicity through UV illumination. The degradation efficiency of the thin films increases with decreasing EGME content, photocatalytic reaction mechanism of the ZnO thin films is discussed in detail.