Materials Literature
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A new synthesis concept in cellulose chemistry is described. Cellulose dissolved in the solvent system N,N -dimethylacetamide/LiCl as well as organo-soluble cellulose derivatives of different hydrolytic stability (dissolved in dimethyl sulfoxide) were converted into cellulose ethers of unusual substituent patterns aft…
Both “condensation” and “hydrosilylation” reactions have been successfully applied for the synthesis of silicon-based interpenetrating polymer networks (IPNs) consisting of a stable Si−O and Si−C linkage. We adopted a ladder silsesquioxane oligomer (LDS 1; commercial name, Glass Resin GR100) and a polycarbosilane (PCS…
Electrochemical oxidation of the tetrathiafulvalene (TTF) type organic donor bis(ethylenediseleno)tetrathiafulvalene (BEST) in the presence of the Keggin polyoxometalate [PMo(12)O(40)](3)(-) affords the radical salt formulated as (BEST)(3)H[PMo(12)O(40)] (crystal data: triclinic, space group P&onemacr; with a = 13.056…
The photochemical and photophysical behavior of (dodecafluorosubphthalocyanaoto)boron(III) chloride was examined in room-temperature solutions. The lowest energy absorption maximum of the complex is 570 nm, and the luminescence mirrors the absorption with a maximum at 586 nm (Stokes shift = 480 cm -1 ). The emission i…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTPractical Synthesis of Starburst PAMAM α-Thiosialodendrimers for Probing Multivalent Carbohydrate−Lectin Binding PropertiesDiana Zanini and René RoyView Author Information Department of Chemistry, University of Ottawa, Ottawa, ON, Canada K1N 6N5 Cite this: J. Org. Chem. 1998, 6…
Polymer complexes of a basic polymer, poly( N- methyl-4-piperidinyl methacrylate) (PMPMA), with a weak acidic polymer poly( p -vinylphenol) (PVPh), and strong acidic polymers such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(styrenesulfonic acid) (PSSA), and poly(vinylphosphonic acid) (PVPA), have…
Obstacles to the heterogeneous esterification of cellulose with long-chain alkanoic acids were overcome (a) by reacting cellulose in homogeneous phase solution (in DMAc/LiCl) in the presence of dicyclohexyldicarbodiimide (DCC) and 4-pyrrolidinopyridine (PP) or tosyl chloride; or (b) by reaching cellulose heterogeneous…
Dihydridocarbonyltris(triphenylphosphine)ruthenium catalyzed copolymerization of acetophenone and 1,4-bis((trimethylsilyl)ethynyl)benzene yields a linear copolymer copoly[2-acetyl-1,3- phenylene/α,α‘-bis((trimethylsilyl)methylene)-1,4-xylenylene]. This reaction involves regioselective catalytic addition of the ortho C…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTLinear and Hyperbranched m-Polyaniline: Synthesis of Polymers for the Study of Magnetism in Organic SystemsNikolaos Spetseris, Rachel E. Ward, and Tara Y. MeyerView Author Information Department of Chemistry, University of Pittsburg…
Novel solvent systems for cellulose are reviewed in terms of their potential for supporting chemical modification reactions that lead to highly engineered derivatives. Systems capable of sustaining homogeneous phase conditions include (1) dissolution with non-derivatizing solvents; (2) dissolution with partial derivat…
The effect of the overall crystallinity and the initial crystal morphology on the welding behavior of semicrystalline polymers was investigated by means of T-peel testing above and below the melting point using ultrahigh-molecular-weight polyethylene (UHMWPE) as a model polymer. Different crystal morphologies were gen…
Crystalline cyclic poly(oxyethylene)s with number-average molar masses ( M n ) of 4000, 6000, and 10000 g mol -1 were studied by wide-angle (WAXS) and small-angle (SAXS) X-ray scattering, high-frequency and low-frequency laser-Raman spectroscopy, and differential scanning calorimetry (DSC). The subcell of the crystall…
A pure silica MCM-41 preparation with high crystalline order perpendicular to the channels has been examined using small-angle neutron scattering and the contrast variation method in both the calcined and template-containing forms. This defines various structural features such as template and water distributions and c…
A layer-by-layer film could be fabricated on a substrate by the consecutive adsorption method based on the charge-transfer (CT) interaction between electron-donating carbazolyl groups and electron-accepting 3,5-dinitrobenzoyl groups in the side chains of two kinds of methacrylate polymers, poly[2-(9-carbazolyl)ethyl m…
A novel flavonoid diglycoside, 5,6,7,4'-tetrahydroxyflavonol 3-O-rutinoside (1), and a previously known compound, kaempferol 3-O-neohesperidoside (2), were isolated from an ethyl acetate extract of Daphniphyllum calycinum leaves that showed significant activity in a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical as…
Amphiphilic hydrogen bond networks consisting of alkylated melamines and ammonium headgroup-appended cyanuric acids are stably dispersed in water as supramolecular membranes. Electron micrographs of these aqueous dispersions indicated the formation of supramolecular assemblies of mesoscopic dimension. Their aggregate…
Single-component monolayers of dendrimers and two-component monolayers consisting of dendrimers and n -alkanethiols immobilized on Au substrates are described. Single-component monolayers are prepared by exposing an Au substrate to ethanolic solutions of amine- or hydroxy-terminated polyamidoamine (PAMAM) dendrimers.…
The lifetime of image states, which represent a key quantity to probe the coupling of surface electronic states with the solid substrate, have been recently determined for quantum numbers $n\le 6$ on Cu(100) by using time-resolved two-photon photoemission in combination with the coherent excitation of several states (…
The electronic response of a composite consisting of aligned metallic cylinders in vacuum is investigated, on the basis of photonic band structure calculations. The effective long-wavelength dielectric response function is computed, as a function of the filling fraction. A spectral representation of the effective resp…
Heat capacity measurements on the prototypical three-dimensional random-field Ising model compound Fe0.58Zn0.42F2 have been performed in both of the field-cooling (FC) and zero-field-cooling (ZFC) procedures. There is no evidence of hysteresis between the FC and ZFC protocols within the experimental accuracy. The abse…