Hydroxy Ether Research Articles

In Quest of the Missing C2H6O2 Isomers in the Interstellar Medium: A Theoretical Search.

Ethylene glycol (C2H6O2), the only diol detected in the interstellar medium (ISM), is a key component in the synthesis of prebiotic sugars. Its structural isomer, methoxymethanol, has also been found in the ISM. Our results show that neither ethylene glycol (ethane-1,2-diol) nor methoxymethanol is the most stable isomer. Using high-level computational methods, we identified five isomers: two diols, one hydroxy ether, and two peroxides. The geminal diol 1,1-ethanediol (ethane-1,1-diol) is the most stable isomer, although it has not been detected in the ISM, whereas the two peroxides are less stable than the geminal diol by 60 kcal/mol. This study also provides the rotational constants and dipole moment for each conformer of every C2H6O2 isomer.

Atmospheric degradation of 2-Isopropoxyethanol: Reactions with Cl, OH and NO3

The use of glycol ethers as solvents and chemical intermediates has increased markedly in recent years. Once released into the atmosphere, they can undergo degradation processes mainly by reactions with the atmospheric oxidants that can have significant effects on the environment. In this work, the kinetic and products study of reactions of 2-isopropoxyethanol (2-iPE, (CH3)2CHOCH2CH2OH) with OH and NO3 radicals and Cl atoms have been performed using FTIR (Fourier Transform Infrared Spectroscopy) and GC-MS (Gas Chromatography/Mass Spectrometry) as detection techniques. The rate coefficients obtained were (units cm3 molecule−1 s−1): (2.18 ± 0.15) × 10−10, (1.88 ± 0.10) × 10−11 and (3.16 ± 0.45) × 10−15 for Cl, OH· and NO3· reactions, respectively. The kinetic results obtained have been included in comparison tables of the general reactivity of hydroxy ethers to extract conclusions of the atmospheric behaviour of this type of compounds. The main products detected and quantified have been isopropyl formate, formaldehyde, 2-hydroxyethyl acetate and, in the case of NO3· reactions, nitrated compounds. A reaction mechanism has been proposed according to the reaction products obtained. The calculated lifetimes have been determined and Global Warming Potential (GWP) and Photochemical Ozone Creation Potential (POCPE) have been estimated, concluding, first, that the reaction with OH radicals is the main pathway of degradation of this and others glycol ethers in the atmosphere, second, that these compounds have GWP negligible and third, that they could have influence on ozone generation at local and regional level.

Molecular dynamics of epoxy nanocomposites filled with core–shell and hollow nanosilica architectures

Here we contrast the molecular dynamics of epoxy nanocomposites filled with three different types of silica-based nanoparticles with different architectures, namely solid core, core–shell and hollow and with varying degree of crystallinity. The samples are characterised by Fourier transform infrared spectroscopy, differential scanning calorimetry, broadband dielectric spectroscopy and dynamic mechanical analysis (DMA). Widely known relaxations such as α, β, γ, normal mode and interfacial polarisation are observed and discussed. An additional relaxation named omega (ω) is also observed, whose dielectric strength is inversely correlated to the crystallinity of the nanoparticles. We suggest that this may be attributed to the polarizing interaction of the hydroxyl groups of silanols with the hydroxy ether groups of the polymer chain. The ω is absent in DMA confirming it as a polarisation phenomenon. At lower concentration of silanols, the ω largely overlaps with β, effectively becoming an integral part of it. Finally, two interfacial polarisation relaxations are observed in the case of core–shell structures, originating from the core–shell and shell–polymer interface but, due to the similar real permittivity values of the core, shell and the polymer, their dielectric strength is weak.

Experimental research on spontaneous combustion of coal oxidized by ultraviolet photocatalysis

To study the effect of ultraviolet light on the spontaneous combustion characteristics of coal, Lijiahao long-flame coal was selected for irradiation treatment with a self-made ultraviolet light irradiation device. After irradiation for 0, 1, 2, 4, and 8 h, thermogravimetric experiments and Fourier transform infrared spectroscopy experiments were carried out. Compared with the raw coal, the dry cracking temperature, the ignition point temperature, and the maximum weight loss rate temperature of coal samples irradiated for 2 h by ultraviolet light were advanced to different degrees. The ignition activation energy was 0.62, 0.56, 0.59, and 0.91 times that of the raw coal after 1, 2, 4, and 8 h of ultraviolet light irradiation. The ultraviolet light irradiation accelerated the oxidation of –CH3, –CH2−, and –OH, resulting in enhanced coal activity. It shows that ultraviolet light irradiation has a promoting effect on the spontaneous combustion of coal, and the best promotion effect is observed when ultraviolet light is irradiated for 2 h. After 2 h of ultraviolet light irradiation, compared with the raw coal, the content of ether group in the coal structure decreased by 6.79%, the content of methyl and methylene in the benzene ring decreased by 8.68%, the content of C=O and carboxylic acid increased by 30.21%, the content of hydroxy ether and hydroxyl π hydrogen bond decreased by 14.94%, and the content of self-associating hydroxyl hydrogen bonds increased by 16.59%. It shows that ultraviolet light can destroy aromatic hydrocarbons in coal, catalyze the hydrolysis reaction of esters and ethers in coal to generate –OH and –COOH, and promote the oxidative spontaneous combustion of coal.

Ziziphus oenoplia Mill.: A Systematic Review on Ethnopharmacology, Phytochemistry and Pharmacology of an Important Traditional Medicinal Plant.

Ziziphus oenoplia Mill. (Family- Rhamnaceae) an important shrub, often found throughout the hot regions of tropical Asia and northern Australia, is commonly well known as Jackal jujube in English. It is a folk herbal medicine used as an abdominal pain killer and antidiarrhoeal agent. The review aims to provide up-to-date information on the vernacular information, botanical characterization, distribution, ethnopharmacological uses, pharmacological activities, and chemical constituents of Z. oenoplia for possible exploitation of treatment for various diseases and to suggest future investigations. This review was performed by studying online resources relating to Z. oenoplia and diverse resources, including scientific journals, books, and worldwide accepted databases from which information was assembled to accumulate significant information and relevant data in one place. Investigations on Z. oenoplia have been focused on its pharmacological activities, including its antimicrobial, antidiabetic, antihepatotoxic, antiulcer, antiplasmodial, anticancer, wound healing, anthelmintic, antioxidant, analgesic and antinociceptive, hypolipidemic activity, anti-inflammatory, immunomodulatory and antidiarrheal activities. Phytochemical studies resulted in the isolation of fatty acids, flavonoids, phenols, pentacyclic triterpenes, hydroxycarboxylic acids, aliphatic hydroxy ether, and cyclopeptide alkaloids. Most of the ethnopharmacological relevance of Z. oenoplia is justified, but more studies are needed. Further investigations are necessary to fully understand the mode of action of the active constituents and to exploit its preventive and therapeutic potentials.

The Mechanical Characterization of Welded Hybrid Joints Based on a Fast-Curing Epoxy Composite with an Integrated Phenoxy Coupling Layer.

The joining of composites mostly relies on traditional joining technologies, such as film or paste adhesives, or mechanical fasteners. This study focuses on the appealing approach of using standard thermoplastic welding processes to join thermosets. To achieve this, a thermoplastic coupling layer is created by curing with a thermoset composite part. This leads to a functional surface that can be utilized with thermoplastic welding methods. The thermoplastic coupling layer is integrated as a thin film, compatible with the thermoset resin in the sense that it can partially diffuse in a controlled way into the thermoset resin during the curing cycle. Recent studies showed the high affinity for the interphase formation of poly hydroxy ether (phenoxy) film as coupling layer, in combination with a fast-curing epoxy system that cures within 1 min at 140 °C. In this study, an investigation based on resistance and ultrasonic welding techniques with different testing conditions of single-lap shear samples (at room temperature, 60 °C, and 80 °C) was performed. The results showed strong mechanical strengths of 28.9 MPa (±0.7%) for resistance welding and 24.5 MPa (±0.1%) for ultrasonic welding, with only a minor reduction in mechanical properties up to the glass transition temperature of phenoxy (90 °C). The combination of a fast-curing composite material with an ultra-fast ultrasonic joining technology clearly demonstrates the high potential of this joining technique for industrial applications, such as automotive, sporting goods, or wind energy. The innovation allowing structural joining performance presents key advantages versus traditional methods: the thermoplastic film positioning in the mold can be automated and localized, joint formation requires only a fraction of a second, and the joining operation does not require surface preparation/cleaning or structure deterioration (drilling).

Atmospheric degradation of 3-ethoxy-1-propanol by reactions with Cl, OH and NO3

An experimental kinetic and mechanistic study of the reactions of 3-ethoxy-1-propanol (CH3CH2OCH2CH2CH2OH) with Cl atoms and OH and NO3 radicals has been carried out at room temperature and atmospheric pressure. FTIR (Fourier Transform Infrared Spectroscopy) and GC-MS (Gas Chromatography/Mass Spectrometry) were used as detection techniques. The rate coefficients were measured with a relative method (units cm3 molecule−1 s−1): (3.46 ± 0.22) × 10−10, (3.48 ± 0.19) × 10−11 and (1.08 ± 0.07) × 10−14 for Cl, OH and NO3 reactions, respectively. Qualitative and quantitative products analysis was carried out and formaldehyde, ethyl formate, ethyl 3-hydroxypropanoate and nitrated compounds were positively identified. A reaction mechanism has been proposed which involves attack by the oxidant at the methylene group in the α-position to an oxygen atom of the ether or alcohol groups, followed by the subsequent reactions of the resulting radicals. The tropospheric reactivity of 3-ethoxy-1-propanol (3E1P) has been compared with the reactivity of other hydroxy ethers to extend our knowledge of this type of compound. The atmospheric implications for 3E1P have been established by estimating parameters such as lifetimes, global warming potential (GWP) and the Photochemical Ozone Creation Potential (POCPE). According to the calculated tropospheric lifetimes, the dominant loss process of 3E1P is its daytime reaction with the OH radical and this has an impact on a local scale.

Investigation of the interphase mechanisms and welding behaviour of fast-curing epoxy based composites with co-cured thermoplastic boundary layers

This study focuses on investigating thermoplastic polymers and their interphase behaviour with the fast-curing epoxy system Araldite LY3585/Aradur 3475. The three compatible thermoplastic polymers poly(methyl methacrylate) (PMMA), amorphous polyamide (PA12TR90), and poly(hydroxy ether) (phenoxy) were chosen to determine their affinity and interphase formation with the epoxy system. The final concept involves the use of a thermoplastic as a boundary layer on top of the epoxy to establish a connection between two joined parts by resistance welding. The thermoplastic boundary layer was generated by co-curing during the curing process. The experiments resulted in a high compatibility between phenoxy and PMMA in the selected epoxy system which leads to excellent mechanical properties after welding. Phenoxy showed the strongest joints, with an average lap shear strength of 25 MPa, demonstrating the high potential of this joining technique for industrial applications in the automotive and wind energy fields.

Blends based on biodegradable poly(caprolactone) with outstanding barrier properties for packaging applications: The role of free volume and interactions

In order to improve the poor barrier properties of poly(caprolactone) (PCL) this polymer was blended with poly(hydroxy ether of bisphenol A) (PH). The thermal properties, as well as the free volume of the system were analysed. The incorporation of PH significantly reduces the permeability of poly(caprolactone) to oxygen, carbon dioxide and water vapour. This reduction is linked to the free volume fraction, the thermal properties and the balance of interactions between polymers and penetrants. The outstanding results obtained allow to expand the applications of poly(caprolactone) in the packaging sector. The aim of this work is to achieve a better understanding of the factors that are involved in the barrier character improvement of poly(caprolactone) that could be extended to other biodegradable polymers.

MASS SPECTROMETRIC FRAGMENTATION OF TRIMETHYLSILYL AND RELATED ALKYLSILYL DERIVATIVES.

This review describes the mass spectral fragmentation of trimethylsilyl (TMS) and related alkylsilyl derivatives used for preparing samples for analysis, mainly by combined gas chromatography and mass spectrometry (GC/MS). The review is divided into three sections. The first section is concerned with the TMS derivatives themselves and describes fragmentation of derivatized alcohols, thiols, amines, ketones, carboxylic acids and bifunctional compounds such as hydroxy- and amino-acids, halo acids and hydroxy ethers. More complex compounds such as glycerides, sphingolipids, carbohydrates, organic phosphates, phosphonates, steroids, vitamin D, cannabinoids, and prostaglandins are discussed next. The second section describes intermolecular reactions of siliconium ions such as the TMS cation and the third section discusses other alkylsilyl derivatives. Among these latter compounds are di- and trialkyl-silyl derivatives, various substituted-alkyldimethylsilyl derivatives such as the tert-butyldimethylsilyl ethers, cyclic silyl derivatives, alkoxysilyl derivatives, and 3-pyridylmethyldimethylsilyl esters used for double bond location in fatty acid spectra. © 2019 Wiley Periodicals, Inc. Mass Spec Rev 0000:1-107, 2019.

Improving the barrier properties of a biodegradable polyester for packaging applications

Miscible and thermally stable blends of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) with poly(hydroxy ether of bisphenol A) (PH) are investigated to obtain membranes for packaging applications. Previously the miscibility and adequate degradability of these blends was proven, therefore this system is a good candidate for packaging applications. The crystallinity degree and the free volume, both of crucial importance in transport properties, are analysed as a function of blend composition. The transport properties to different gases and vapours are greatly reduced with the addition of PH. The blends show high elongational viscosity values, which allows expecting good film processability. Overall, this work sheds light on the factors involved in the reduction of permeability which would allow to broaden this strategy to other promising biodegradable materials.

Chemical Interaction-Induced Evolution of Phase Compatibilization in Blends of Poly(hydroxy ether of bisphenol-A)/Poly(1,4-butylene terephthalate).

An immiscible blend of poly(hydroxy ether of bisphenol-A) (phenoxy) and poly(1,4-butylene terephthalate) (PBT) with phase separation was observed in as-blended samples. The compatibilization of phenoxy/PBT blends can be promoted through chemical exchange reactions of phenoxy with PBT upon annealing. The annealed phenoxy/PBT blends had a homogeneous phase with a single Tg that could be enhanced by annealing at 260 °C. Infrared (IR) spectroscopy demonstrated that phase homogenization could be promoted by annealing the phenoxy/PBT blend, where alcoholytic exchange occurred between the dangling hydroxyl group (–OH) in phenoxy and the carbonyl group (C=O) in PBT in the heated blends. The alcoholysis reaction changed the aromatic linkages to aliphatic linkages in the carbonyl groups, which initially led to the formation of a graft copolymer of phenoxy and PBT with an aliphatic/aliphatic carbonyl link. The progressive alcoholysis reaction resulted in the transformation of the initial homopolymers into block copolymers and finally into random copolymers, which promoted phase compatibilization in blends of phenoxy with PBT. As the amount of copolymers increased upon annealing, the crystallization of PBT was inhibited by alcoholytic exchange in the blends.

Miscibility and degradation of polymer blends based on biodegradable poly(butylene adipate-co-terephthalate)

The aim of this work is to analyse the effect of the preparation method on the miscibility of poly(butylene adipate-co-terephthalate) (PBAT) and poly(hydroxy ether of bisphenol A) (PH) blends and to provide a better understanding on the effect of a non-degradable component (PH) in the degradation of biodegradable PBAT. Blends have been prepared by different methods and the miscibility has been studied in a deeper way by means of differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and infrared spectroscopy (FTIR). Depending on the preparation method miscible or partially miscible blends are obtained. Furthermore, for miscible blends the hydrolytic degradation has been carried out for 405 days. It has been observed that adipate sequences on poly(butylene adipate-co-terephthalate) copolymer are more prone to degradation which leads to changes on glass transition temperature, crystallinity and chemical structure. The degradation rate is decelerated with the addition of PH, however the rate is similar or higher than other biodegradable polymers. Therefore the degradation rate can be controlled varying the composition of the blend and tailored materials with adequate properties can be obtained.

Synthesis and characterization of carborane-containing poly(hydroxy ethers) with excellent thermal stability

o-Carborane-containing poly(hydroxy ethers) (P1, P2 and P3) were synthesized via “advancement reaction” of o-carborane-containing bisphenol (4) and diglycidyl ether of bisphenols (DGEBA and 1). FTIR and 1H-, 13C-, and 11B-NMR were utilized to characterize the obtained polymers. TGA test was conducted under nitrogen and air. It is found that the shielding effect of carborane moiety on its adjacent aromatic structures contributes to high initial decomposition temperatures, while oxygen in air has an adverse effect on the initial decomposition temperature. The oxygen can combine with polymer chain to form peroxide and hydroperoxide groups, which are more reactive during the degradation process. Besides, o-carborane-containing poly(hydroxy ethers) have high char yield at elevated temperatures. The boron atom combines with oxygen from the polymer structure or/and from air, thus to form a three-dimensional network linked with B—O—B and B—C bonds, and retain the polymer weight to a large extent.

Improving the barrier character of polylactide/phenoxy immiscible blend using poly(lactide‐co‐ɛ‐caprolactone) block copolymer as a compatibilizer

ABSTRACTThe improvement of the barrier character of polylactide by the addition of poly(hydroxy ether) of bisphenol A (Phenoxy) and poly(lactide‐co‐ɛ‐caprolactone) copolymer that acts as a compatibilizer is studied. First, differential scanning calorimetry, Fourier transformed infrared spectroscopy, and scanning electron microscopy show that the addition of the copolymer allows to obtain a miscible ternary system. The permeability of polylactide to water vapor, oxygen, and carbon dioxide is enhanced with the addition of phenoxy but better improvement in its barrier character is obtained with the addition of the compatibilizer. The effects of different factors such as miscibility, glass transition temperature, and crystallinity on the transport properties are analyzed. Several permeability prediction models for heterogeneous systems have been applied obtaining quite good results for water vapor and oxygen permeability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45396.

Enhancing the Compatibility of Poly (1,4-butylene adipate) and Phenoxy Resin in Blends.

This work concerns the enhancement in the compatibility of blends of poly (1,4-butylene adipate) (PBA) with poly (hydroxy ether of bisphenol-A) (phenoxy) via alcoholytic exchange. Results on the thermal behavior and morphology show that the blended PBA/phenoxy system exhibits a homogeneous phase and a composition-dependent glass transition temperature (Tg). The interaction parameter (χ12) of PBA/phenoxy blends was calculated using the melting point depression method and was found to be −0.336. However, the compatibilization of PBA/phenoxy blends can be enhanced by chemical exchange reactions between PBA and phenoxy upon annealing. Annealed PBA/phenoxy blends were found to have a homogeneous phase with a higher Tg than that of the blended samples, and a smooth surface topography that could be improved by annealing at high temperature. The results of this investigation demonstrate that promotional phase compatibilization in the PBA/phenoxy blend can only be obtained upon thermal annealing, thus causing transreactions to occur between the dangling –OH of the phenoxy and the ester functional groups in PBA. Extensive transreactions cause alcoholytic exchange between the PBA and phenoxy to form a network, thus reducing the mobility of the polymer chain. Finally, the crystallinity of PBA decreased as the degree of transreaction in the blends increased.

Electrical conductivity of melt-spun thermoplastic poly(hydroxy ether of bisphenol A) fibres containing multi-wall carbon nanotubes

Fibres spun from thermoplastic poly(hydroxy ether of bisphenol A) filled with weight fractions of 1, 3, 6, 8 and 12 wt.% of multi-wall carbon nanotubes (MWCNTs) were prepared at elevated process temperatures using a three-roll-mill for homogeneous dispersion of the MWCNTs and a twin-screw compounder with an attached winding roll for fibre spinning. Production caused fibre draw down ratios (DDR) from 1 to a maximum of 54 resulting in fibre diameters from 0.7 mm down to 0.07 mm were used. The state of dispersion of the MWCNTs was characterized by transmission electron microscopy (TEM). The electrical resistivity of the fibres and the percolation threshold were obtained as a function of weight fraction of MWCNTs and the fibre draw down ratio. The effect on resistivity of a subsequent heat treatment at 180 °C and on dissolution of the fibre’s outer layers were analysed when embedded in liquid epoxy resin. Percolation thresholds between 6 wt.% and 12 wt.% were estimated depending on the draw down ratio of the fibres. The observed lowest resistivity was about 5 Ωm for as spun fibres without drawing. It increases over several orders of magnitude to the limit of measurability with increasing the draw down ratio. It was further shown that the resistivity greatly reduced after heat treatment, as well as after embedding the fibres in epoxy resin due to the effect of near surface solubility of the thermoplastic fibre when in contact to the epoxy resin. A reduced percolation threshold of about 6 wt.% can be obtained after heat treatment. Thereby, the production related influence of fibre stretching is largely eliminated.

ChemInform Abstract: Combination of NH2OH·HCl and NaIO4: An Effective Reagent for Molecular Iodine‐Free Regioselective 1,2‐Difunctionalization of Olefins and Easy Access of Terminal Acetals.

AbstractA new application of the entitled oxidizing reagent is used for the regioselective 1,2‐difunctionalization of olefins.

Chemical Exchange Reactions in Blends of the Biodegradable Polyester with poly(hydroxy ether of bisphenol-A)

Compatibilization via transreactions in blends of poly (butylene succinate-co-butylene terephthalate) [P(BS-co-BT)] with poly (hydroxy ether of bisphenol-A) (phenoxy) were investigated. Analyses were based on characterization using differential scanning calorimetry (DSC) and solid-state nuclear magnetic resonance (NMR). They revealed that the P(BS-co-BT)/phenoxy blend had a phase morphology that could be homogenized only following annealing at high temperatures. As-blended P(BS-co-BT)/phenoxy (50/50 composition) exhibited immiscible phases with two distinct Tgs, but the initially phase separated blends finally merged to form a homogeneous phase with a single Tg upon heating and annealing for 60 min at 280 °C. Chemical exchange reactions upon heat-annealing were likely to have caused the phase homogenization in the P(BS-co-BT)/phenoxy blend. NMR was performed on blend samples before and after they were heated to 280 °C, but the similarity of bonds made obtaining straight results difficult. Results of this study demonstrate phase homogenization can be brought only upon heat-annealing in the P(BS-co-BT)/phenoxy blend.

Phase Compatibilization through Chemical Exchange Reactions in Blends of Copolyesters with Poly(hydroxyether of bisphenol A) upon Annealing

Miscibility or compatibilization via transreactions in blends of one of two copolyesters, poly(butylene adipate-co-butylene terephthalate) [P(BA-co-BT)] or poly(butylene succinate-co-butylene terephthalate) [P(BS-co-BT)], with poly(hydroxy ether of bisphenol A) (phenoxy) were investigated. The P(BA-co-BT)/phenoxy blend exhibited a homogeneous phase and a composition-dependent glass transition temperature (Tg) without any heat annealing. The copolymer–polymer interaction parameter (χ12) for the P(BA-co-BT)/phenoxy blend was calculated from the melting-point-depression method to be −0.12. However, variation in the composition and structure of the copolyesters easily causes phase separation in copolyester/phenoxy blends. The P(BS-co-BT)/phenoxy blend had a phase morphology that could be homogenized only following annealing at high temperatures. As-blended P(BS-co-BT)/phenoxy (50/50 composition) exhibited immiscible phases with two distinct Tgs, but the initially phase-separated blends finally merged to form ...