Alkylene Oxide Research Articles

Surfactant-Templated TiO2 (Anatase): Characteristic Features of Lithium Insertion Electrochemistry in Organized Nanostructures

Thin layer electrodes (0.2−0.5 μm) of highly organized nanotextured anatase were prepared by hydrolysis of TiCl4 in the presence of poly(alkylene oxide) block copolymer, Pluronic P-123, acting as the structure-directing agent. Electrochemical properties of these layers were studied in KCF3SO3 + propylene carbonate and in LiN(CF3SO2)2 + ethylene carbonate + dimethoxyethane. The electrodes showed unusually fast capacitive and Li-insertion charging. A most striking effect was the occurrence of two new pairs of peaks in cyclic voltammograms in Li+ containing electrolyte solutions. These, so-called S-peaks, appear in addition to the “ordinary” peaks of Li insertion into anatase. The S-peaks can act as indicators of mesoscopic ordering of the skeleton as they diminish after mechanical or thermal destruction of the organized nanotexture. We suggest that the occurrence of S-peaks is connected to the presence of amorphous TiO2 in the organized skeleton.

Synthesis of oligocarbonate diols and their characterization by MALDI-TOF spectrometry

A method of the synthesis of oligocarbonate diols from five-membered cyclic carbonates and aliphatic diols using azeotropic solvents is presented. The influence of a catalyst and reaction conditions on the alkylene oxide and alkylene carbonate insertion into macrodiol molecules were studied and the reaction mechanism is discussed. The oligomeric products were analyzed by means of MALDI-TOF mass spectrometry. The transesterification reaction between propylene carbonate and diols containing six or more carbon atoms in a molecule carried out in the presence of the coordination catalysts such as tin or zinc carboxylate leads to almost pure oligocarbonate diols.

Chemical and Electrochemical Characterization of Polymer Gel Electrolytes Based on a Poly(alkylene oxide) Macromonomer for Application to Lithium Batteries

Polymer gel electrolytes were prepared from a molecularly designed poly(alkylene oxide) triacrylate macromonomer and different liquid electrolytes. The cross‐linking kinetics of the macromonomer in a liquid electrolyte was studied by using differential scanning calorimetry equipped with ultraviolet light irradiation system (UV‐DSC). It was revealed that the photoinitiated cross‐linking reaction followed the first order kinetics in terms of macromonomer concentration. The cross‐linking reaction finished completely under suitable conditions of ultraviolet (UV) light strength and photoinitiator concentrations. The gel electrolytes prepared exhibited a high ionic conductivity of 3 mS/cm at room temperature and kept 1 mS/cm even at −20°C, when electrolyte was incorporated in the gel. A linear relationship between the ionic conductivity of liquid electrolytes and that of the gel electrolytes containing the corresponding liquid electrolytes was observed, except for the case where was used as an electrolyte salt. The interfacial resistances at the lithium/gel electrolyte interfaces were largely dependent on the kind of liquid electrolytes incorporated in the gels. Preliminary results of the application of the gel electrolytes to lithium and lithium ion batteries implied high utilization of cathode material and cycleability. © 2000 The Electrochemical Society. All rights reserved.

Effects of block architecture and composition on the association properties of poly(oxyalkylene) copolymers in aqueous solution

A block copolymer of hydrophilic poly(ethylene oxide) and a hydrophobic poly(alkylene oxide) can associate in dilute aqueous solution to form micelles. The results of recent investigations of the micellisation behaviour and micelle properties of such copolymers are described. Copolymers of ethylene oxide with propylene oxide, 1,2-butylene oxide or styrene oxide are considered, including aspects of their preparation. Experimental methods for determination of critical conditions for micellisation, micelle association number and spherical-micelle radius are summarised. Effects of temperature, composition, block length and block architecture (diblock, triblock and cyclic-diblock) are described and, where possible, related to the predictions of theory. Brief consideration is given to the dynamics of micelle formation/dissociation, to cylindrical micelles, and to effects of added salts.

Oxyethylation and oxypropylation of alcohols of low relative molecular mass in the presence of amine-type catalysts

The effect of an amine catalyst on oxyalkylation of alcohols of low relative molecular mass was studied. The reactivity and selectivity of the formation of the first homologues depend upon the alcohol, the alkylene oxide and the degree of oxyalkylation and decrease in the following order methanol>ethanol>butanol>2-methylpropanol. The formation of the first homologue is significantly more selective in oxypropylation in comparison to oxyethylation. Triethylamine used as the catalyst undergoes by-reactions giving N,N-diethylethanolamine and then oxyethylated diethylamines which exhibit catalytic activity.

Polyglycols as base fluids for environmentally‐friendly lubricants

AbstractPolyglycols are used in a wide range of applications, including lubrication. Many advantageous properties can be obtained for lubricant applications by manipulating the four variables in polyglycol preparation: the initiator, the alkylene oxides, the molecular build‐up, and the mole weight. However, it has long been believed that it would not be possible to combine these properties with a good environmental profile of high biodegradability and low aqueous toxicity. Development work at the authors' laboratory has resulted in polyglycol‐chemistry‐based products that fulfil the application requirements and are also environmentally friendly. Assessment by the Umwelt Bundes Amt has led to a statement of suitability for Blue Angel formulations for two water‐soluble polyglycol grades (ISO 22 and IS0 46). Environmentally‐friendly watersoluble polyglycol base stocks currently includes the range ISO 10 to ISO 100. The development of environmentally friendly water‐insoluble and oil‐soluble polyglycols is under way.

A novel oxidative alkylation–nitration of 1,3-dicarbonyl compounds to dicyclopentadiene and norbornene †

A one-pot CAN-mediated oxidative alkylation–nitration of endo-dicyclopentadiene and norbornene with 1,3-dicarbonyl compounds is described. The key step involves the Wagner–Meerwein rearrangement of 2 which leads to the exo-dicyclopentadienyl nitrate 4.

Novel gel polymer electrolytes based on alkylene oxide macromonomer

A novel gel polymer electrolyte, based on alkylene oxide macromonomer, was specially designed and synthesized for gel electrolyte purpose. A tri-functional macromonomer having a molecular weight of 8000 revealed to be the best candidate for preparing the gel electrolyte from the mechanical property aspect. The liquid retention ability of the cross-linked network polymer prepared from the above macromonomer was explored. It was confirmed that the polymer network based on the macromonomer retained a large amount of liquid electrolyte over 80 wt.% in stable state.

Block Copolymer Templating Syntheses of Mesoporous Metal Oxides with Large Ordering Lengths and Semicrystalline Framework

A simple and general procedure has been developed for the syntheses of ordered largepore (up to 14 nm) mesoporous metal oxides, including TiO2, ZrO2 ,N b 2O5 ,T a 2O5 ,A l 2O3, SiO2, SnO2 ,W O 3, HfO2, and mixed oxides SiAlOy ,A l 2TiOy, ZrTiOy, SiTiOy, ZrW2Oy. Amphiphilic poly(alkylene oxide) block copolymers were used as structure-directing agents in nonaqueous solutions for organizing the network-forming metal oxide species. Inorganic salts, rather than alkoxides or organic metal complexes, were used as soluble and hydrolyzable precursors to the polymerized metal oxide framework. These thermally stable mesoporous oxides have robust inorganic frameworks and thick channel walls, within which high densities of nanocrystallites can be nucleated. These novel mesoporous metal oxides are believed to be formed through a mechanism that combines block copolymer self-assembly with alkylene oxide complexation of the inorganic metal species.

Behavior of interfacial resistance at lithium electrode for gel electrolyte using novel three-dimensional network polymer host

Abstract A novel macromonomer based on tri-functional poly (alkylene oxide) main chain with acrylate chain ends was specially designed and synthesized for gel electrolyte purpose. Various kinds of gel electrolyte, based on the crosslinked macromonomer, were prepared. Interfacial resistance between lithium electrodes and the gel electrolytes was measured. The significant decrease in interfacial resistance was observed during 4–6 h after assembling the cell. The discharge capacity of secondary cells with the gel electrolyte depended on the kind of liquid electrolyte incorporated in the gel electrolyte.

Application of gel alkylene oxide electrolytes to rechargeable lithium batteries

Advanced gel polymer electrolytes of alkylene oxide system were prepared. The base polymer was random copolymer of alkylene oxide system (MW: 8000, ethylene oxide (EO): ca. 80%, propylene oxide (PO): ca. 20%, end functional group: acrylic group). The gel polymer electrolyte was prepared by mixing the base polymer, a solvent, a lithium salt and an initiator followed by UV irradiation. Ionic conductivity of gel polymer electrolyte was measured with ac method at temperature range between −20 and +60°C. The ionic conductivity reached over 2.5 mS cm −1 at 20°C when LiBF 4 /γ-butyrolactone (GBL) solution was incorporated as an electrolyte. The discharge capacity with charge-discharge cycle of test cells, C n -Li/LiCoO 2 , with the gel polymer electrolyte was more stable during cycling than that with liquid organic electrolyte solution. It was affected by the kind of plasticizer in the gel electrolyte. The capacity of the test cell was limited by the weight of cathode active material (1.3 mAh). The highest discharge capacity was attained using C n -Li/the base polymer–GBL–LiBF 4 /LiCoO 2 and its utilization rate of the cathode material was 83%.

ChemInform Abstract: Catalytic Selective Oxidation of Alkyl Arenes to Aryl tert. Butyl Peroxides with TBHP over Ru‐Exchanged Montmorillonite K10.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Preparation, Mechanical Properties, and Electrochemical Characterization of Polymer Gel Electrolytes Prepared from Poly(alkylene oxide) Macromonomers

Various kinds of macromonomers have been specially designed and systematically synthesized for their application to polymer gel electrolyte hosts. Poly(alkylene oxide) was selected for the polymer backbone, and its chain ends were modified to form acryloyl groups. The gel electrolytes were prepared by cross‐linking the macromonomers dissolved in a liquid electrolyte of 1 mol/L in propylene carbonate. Mechanical and electrochemical properties of the gel electrolytes were explored in detail. The results of tensile strength, elongation at break, and shear modulus measurements suggested that a favorable cross‐linking reaction proceeded in the polymer gel electrolytes. Cross‐linked macromonomer films showed excellent swelling characteristics for liquid‐electrolyte uptake and this led to stable liquid retention. High ionic conductivity was attained while keeping sufficient mechanical strength, reflecting stability of the liquid uptake process. The potential stability windows of the gel electrolytes, determined by cyclic voltammetry measurements, were as high as 4.5 V vs. . © 1999 The Electrochemical Society. All rights reserved.

Catalytic selective oxidation of alkyl arenes to aryl tert. butyl peroxides with TBHP over Ru-exchanged montmorillonite K10

A mild and efficient catalytic method for the benzylic oxidation of alkyl arenes to the corresponding tert. butyl aryl peroxides is described using a catalytic amount of reusable solid, Ru III-exchanged Montmorillonite K10 and 70% tert. butyl hydroperoxide (TBHP) as oxidant.

Fluoride-Induced Hierarchical Ordering of Mesoporous Silica in Aqueous Acid-Syntheses

The acid-catalyzed synthesis of highly ordered mesostructured materials has led to a variety of twoand three-dimensional periodic symmetries, and has proven to be an effective route for the generation of fibers, spheres, thin films, and other monolithic forms of mesoporous materials. Zhao et al. recently used non-ionic poly(alkylene oxide) block copolymers, under acidic conditions, to prepare well-ordered, hexagonal mesoporous silica, denoted SBA-15, featuring uniform and adjustable large pore sizes combined with thick hydrothermally stable walls. The catalytic effect of fluoride in the synthesis of mesoporous silica at neutral to basic pH has been described by Voegtlin et al. Fluoride has been successfully used to extend the pH range over which anionic silica precursors can be utilized to create organized periodic structures; it has been used to diminish framework defects in zeolites, and to improve the organization in MCM-41 molecular sieves and MSU-X materials. However, to the best of our knowledge, no studies have been reported on the role of fluoride on cationic silica species in the aqueous acid-synthesis of ordered porous silica. In this communication, we describe the hierarchical ordering effects induced by small amounts of fluoride added during the synthesis of SBA-15-type mesoporous silica under acidic aqueous conditions. The non-ionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymer EO20PO70EO20 (Pluronic P123) has been employed as the structure-directing agent. At low pH, remarkably well-ordered, hydrothermally stable, large hexagonal mesoporous silica rods with uniform channels extending over micrometer-sized length scales, and with few defects, have been synthesized. The fluoride-induced enhancement of order has enabled the preparation of SBA-15 materials at moderate acidity (~ pH 2.5±3) without compromising the long-range hexagonal symmetry. The mesoporous silicas possess narrow pore-size distributions, hydrothermally stable frameworks, large surface areas, and pore volumes of up to 0.92 cm/g. This work has been motivated by our interest in i) the patterning of mesoporous materials ranging from mesoscopic to macroscopic length scales while retaining molecular-level structural control and ii) understanding the underlying mechanism for the acid-catalyzed mesoporous silica synthesis. Addition of small amounts of fluoride (F:Si molar ratios of 0.008 and 0.03; fluoride source: NH4F or (NH4)2SiF6) during the aqueous acidic SBA-15-type silica synthesis induces substantial ordering that is manifested on different length scales: both the mesoscopic structure and the macroscopic morphology of the mesoporous silicas are significantly improved. Scanning electron microscopy (SEM) has revealed that small amounts of fluoride bring about the formation of large mesoporous silica rods (Fig. 1a) when pre-

Tyrosine–PEG-derived poly(ether carbonate)s as new biomaterials: Part II: study of inverse temperature transitions

Tyrosine–poly(alkylene oxide)-derived poly(ether carbonate)s represent a new group of degradable biomaterials that exhibit inverse temperature transitions. Poly(DTE co 70%PEG 1000 carbonate) was chosen as an example to study this special phase transition behavior of the polymers. The observed transition temperature varied slightly depending on the technique used, e.g. CD always gave a lower temperature than UV/Vis. CD and UV/Vis studies indicated that the transition temperature was both heating rate and concentration dependent. Thermodynamic parameters of the transition (enthalpy, entropy, and free energy) were determined by DSC. The molecularity of the transition was 2.6, as calculated from UV and DSC data. The transition temperature could be varied from 18 to 58°C by changing the polymer structure. The new poly(ether carbonate)s may be used in medical applications such as injectable drug delivery formulations and bioresorbable barriers for the prevention of surgical adhesions.

Application of Alkylene Oxide Gel Polymer Electrolytes to Lithium Rechargeable Batteries

Application of Alkylene Oxide Gel Polymer Electrolytes to Lithium Rechargeable Batteries

Silicate xerogels containing cobalt as heterogeneous catalysts for the side-chain oxidation of alkyl aromatic compounds with tert-butyl hydroperoxide

New transition metal substituted silicate xerogels, ML n –SiO 2, have been prepared by the sol–gel technique and have been used as heterogeneous catalysts for the side-chain oxidation of alkyl arenes with anhydrous t-butylhydroperoxide. The cobalt substituted silicates were the most active and selective, for example, ethylbenzene was cleanly oxidized to acetophenone at 65% conversion and >99% selectivity. The metal salt precursor used was a key factor in determining the activity of the metallosilicate. Diffuse reflectance UV-vis and IR measurements indicated that when using Co(OAc) 2 as metal precursor, the acetate group was detached from the metal and Co(II) was tetrahedral and site substituted in the silicate network. Addition of the oxidant led to stabilization of a Co(III) oxidation state and/or retention of the tetrahedral configuration.

Generalized syntheses of large-pore mesoporous metal oxides with semicrystalline frameworks

Surfactants have been shown to organize silica into a variety of mesoporous forms, through the mediation of electrostatic, hydrogen-bonding, covalent and van der Waals interactions1,2,3,4,5,6,7,8. This approach to mesostructured materials has been extended, with sporadic success, to non-silica oxides5,6,7,8,9,10,11,12,13,14,15,16,17, which might promise applications involving electron transfer or magnetic interactions. Here we report a simple and versatile procedure for the synthesis of thermally stable, ordered, large-pore (up to 140 A) mesoporous metal oxides, including TiO2, ZrO2, Al2O3, Nb2O5, Ta2O5, WO3, HfO2, SnO2, and mixed oxides SiAlO3.5, SiTiO4, ZrTiO4, Al2TiO5 and ZrW2O8. We used amphiphilic poly(alkylene oxide) block copolymers as structure-directing agents in non-aqueous solutions for organizing the network-forming metal-oxide species, for which inorganic salts serve as precursors. Whereas the pore walls of surfactant-templated mesoporous silica1 are amorphous, our mesoporous oxides contain nanocrystalline domains within relatively thick amorphous walls. We believe that these materials are formed through a mechanism that combines block copolymer self-assembly with complexation of the inorganic species.

ChemInform Abstract: Oxidative Alkylation of Azoles. Part 5. Synthesis of 4‐Nitro‐N‐chloroimidazole and Its Reaction with Methyl Iodide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.