Materials Literature
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The X-ray crystal structures of K6[CoII W12O40]·~16H2O and K5[CoIIIW12O40]·~16H2O are reported. The compounds are isostructural, hexagonal, space group P 6222, and have Z 3 with a 19.118(7), c 12.383(9) Å, V 3919.6(35) Å3 , and a 19.111(2), c 12.509(2) Å, V 3956.6(9) Å3 , respectively. Both anions exhibit the standard…
Three explicit mathematical models have been developed to predict glass transition temperatures of binary polymer−diluent and polymer−salt systems as well as ternary polymer−diluent−salt systems based on the configurational entropy model and the Flory−Huggins theory. In the presence of salt, the specific ionic interac…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTComplete Assignment of 1H and 13C NMR Spectra of Poly(N-vinylcarbazole)Aglaia Karali, George E. Froudakis, Photis Dais, and Frank HeatleyView Author Information NMR Laboratory, Department of Chemistry, University of Crete, 714 09 Iraklion, Crete, Greece Department of Chemistry,…
The dendritic growth of crystals under gravity influence shows a strong dependence on convection in the liquid. The situation is modelled by the Stefan problem with a Gibbs-Thomson condition coupled with the Navier-Stokes equations in the liquid phase. A finite element method for the numerical simulation of dendritic…
The dynamics of cross-linked polymer chains in solution near the gelation threshold has been investigated by dynamic light scattering. The time−intensity correlation function (ICF) was obtained as a function of initial monomer concentration, C NIPA, and cross-linker concentration, C BIS, where NIPA and BIS denote N -i…
A series of fourteen derivatives of adamantane was synthesised. The new compound 4-(adamant-1-ylmethoxycarbonyl)phthalanhydride obtained from 1-adamantane-methanol and trimellitic anhydride chloride appeared very useful for preparation of a number of N-substituted phthalimides. Antimicrobial activity of the newly obta…
[formula: see text] New unsymmetrically substituted DB24C8-phthalocyanines, which are able to form complexes with suitable dialkylammonium cations, have been prepared. These complexes most probably have a pseudorotaxane geometry.
Crystallization and solidification in polymers is a problem of great importance to the polymer processing industry. In these processes, the melt is subjected to deformation while being cooled into the desired shape. The properties of the final product are strongly influenced by the deformation and thermal histories an…
The sub-glass-transition viscoelastic and physical aging responses of an amorphous poly(ethylene naphthalate) (PEN) have been studied using uniaxial tension stress relaxation experiments. It is known that PEN exhibits a strong β relaxation that overlaps the α relaxation in the experimental time and temperature ranges…
Aromatic polyamide dendrons (HOOC-G1 ( 6 ), Br-G2 ( 7 ), HOOC-G3 ( 8 ), and Br-G4 ( 9 )) were synthesized by an orthogonal approach, which utilizes the direct condensation reaction and palladium-catalyzed carbon monoxide insertion reaction in an alternating fashion to form amide linkages. G1, possessing four amino gro…
We investigated the nature and the range of interactions between negatively charged polyelectrolyte-coated surfaces as a function of salt concentration using the surface forces apparatus. The measured force profiles (interaction forces versus separation distance) are purely repulsive and show long-range electrostatic…
ζ potential measurements were used to determine the adsorbed layer thickness of poly(ethylene oxide)−polypropylene oxide−poly(ethylene oxide) (PEO−PPO−PEO) block copolymers at the surfaces of poly(dimethylsiloxane) emulsion droplets, silica particles, and polystyrene latex particles. The adsorbed layer thickness (δ) w…
Three hyperbranched aromatic polyamides were synthesized by the direct polycondensation of 3,5-diaminobenzoic acid 2 (AB 2 monomer), G1 dendron 4 (AB 4 monomer), and G2 dendron 6 (AB 8 monomer). The weight-average molecular weights ( M w ) of the resulting polymers were 100 000−200 000 with a polydispersity (PDI) of c…
The photophysical and hydrodynamic properties of dendrimers (G n PZn and G n TPPH 2 ) with zinc porphyrin (PZn) and tetraphenylporphyrin (TPP) cores are studied in tetrahydrofuran (THF) and dimethylformamide (DMF). UV−vis absorption spectra of G n PZn exhibit a small red shift of the Soret band upon increasing the gen…
The alkaline hydrolysis of a polyimide (PMDA-ODA) surface was studied as a function of time, temperature and hydroxide ion concentration. Quantification of the number of carboxylic acid groups formed on the modified polyimide surface was accomplished by analysis of data from contact angle titration experiments. Using…
Micrometer-sized polystyrene (PS) particles coated with poly(3,4-ethylenedioxythiophene) (PEDOT), an air-stable organic conducting polymer, have been described previously ( Langmuir 1999, 15, 3469). X-ray photoelectron spectroscopy (XPS) was used to examine the surface of these coated particles. For the first time, bo…
An oxalate-bridged 3d−5f compound, K2MnU(C2O4)4·9H2O, is the product of the reaction of K4U(C2O4)4 with a Mn(II) salt. Single-crystal structure analysis shows a three-dimensional network with a diamond-type architecture. The magnetic properties have been examined.
Electrical conductivity measurements on a 2D packing of metallic beads have been performed to study internal rearrangements in weakly pertubed granular materials. Small thermal perturbations lead to large non gaussian conductance fluctuations. These fluctuations are found to be intermittent and gathered in bursts. The…
In sonochemical processes, the physical and chemical effects are attributed to the phenomenon of cavitation, which is the formation, growth, and collapse of the cavities termed as activity of cavities. Energy analysis of a single cavity has been considered in order to explain, qualitatively, the effects of acoustic pa…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSpeciation and Thermal Transformation in Alumina Sols: Structures of the Polyhydroxyoxoaluminum Cluster [Al30O8(OH)56(H2O)26]18+ and Its δ-Keggin MoietéJ. Rowsell and L. F. NazarView Author Information Department of Chemistry, University of Waterloo Waterloo, Ontario,…