Materials Literature
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Neutron reflectivity has been used to study the organization of self-assembled multilayers of sulfonated polyaniline and polyallylamine. Films were prepared by the sequential adsorption of polycations and polyanions from dilute aqueous solutions. Scattering contrast was achieved by selective deuteration of the blocks…
The effect of structure of mesogenic diacrylate monomer and temperature of photopolymerization on the morphology of polymer networks has been studied in detail. Increasing the temperature of photopolymerization increases the size of the constituent units and correspondingly the size of the pores of the polymer network…
The ground state geometry, force field, and vibrational intensity data of free-base porphine were determined by the scaled quantum mechanical (SQM) method, using a force field calculated by density functional theory. Calculations were carried out with the Becke−Lee−Yang−Paar composite exchange-correlation functional (…
The kinetics for the uptake of N 2 O 5 with NaCl [N 2 O 5 (g) + NaCl(s) → ClNO 2 (g) + NaNO 3 (s) (reaction 1)] and KBr[N 2 O 5 (g) + KBr(s) → products (reaction 6)] have been studied in a Teflon-coated Knudsen reactor. The product of reaction 1 is found to be ClNO 2, in agreement with previous studies. The only bromi…
Temperature-programmed desorption (TPD) has been used to compare the O 2 desorption characteristics of a thin film of ceria prepared by vapor deposition on an α-Al 2 O 3 (0001) substrate with that of a CeO 2 (111) surface. On CeO 2 (111), there is no substantial desorption of O 2 below ∼1300 K, while a low-temperature…
The effect of liposome composition on drug delivery to tumors and therapeutic efficacy of liposome-encapsulated anthracyclines was investigated in two murine tumor models: an ascitic tumor (J6456 lymphoma) and a solid carcinoma (M-109). Longevity in circulation correlated positively with high drug levels in the extrac…
Polymers containing in the chain backbone carbazoles substituted with two acceptor groups as nonlinear optical chromophores have been synthesized from 3,6-diformyl-9-heptylcarbazole and bis(cyanoacetate) by the Knoevenagel polycondensation. A one-stage polycondensation was carried out in tetrahydrofuran (THF) solution…
Light-induced reactions of Si surfaces with carboxylic acids to generate Si ester-modified surfaces are studied. The reaction proceeds by photoelectrochemical oxidation of porous or (100)-oriented single-crystal n-type Si in formic, acetic, or trifluoroacetic acid electrolyte solutions. The reaction products at the po…
The details of solution structure have proven difficult to probe experimentally, but computer simulations allow solvent structuring to be examined directly. We report here molecular dynamics (MD) simulations of a series of pentose sugars in solution, describe in detail the three-dimensional structuring which these mol…
A detailed analysis of the Raman spectrum of syndiotactic polystyrene, sPS, in the region 600−850 cm -1 has been undertaken. As sPS exhibits considerable polymorphism, spectra of various preparations including melt-crystallized sPS (α/β form), solvent-crystallized sPS (γ/δ forms), and quenched glassy material were stu…
A mechanism for growth on the diamond (110) surface, with dicarbon (C 2 ) as the growth species, is examined. Reaction energies and activation energies of the various steps in the mechanism were investigated on model systems using molecular quantum mechanics, including the AM1 semiempirical method and the BLYP/6-31G*…
We present a new scaling approach to describe an arbitrarily dense polymer interface (layer made of overlapping polymer chains). Our analysis is based on a description of the layer in terms of loops and tails. Within a simple scaling model for the behavior of the loops and tails, we are able to relate the features of…
Chemically stable poly[2-(3,5-di- tert -butyl-4-oxyphenyl)-1,4( p )-phenylenevinylene], poly[4-(3,5-di- tert -butyl-4-oxyphenyl)-1,3( m )-phenylenevinylene], and poly[4-(3,5-di- tert -butyl-4-oxyphenyl)-1,2( o )-phenylenevinylene] were synthesized via the polymerization of 4-bromo-2-(3,5-di- tert -butyl-4-acetoxypheny…
Transition-metal carbide nanorods have been prepared by reacting carbon nanotubes with volatile Ti and Nb iodides. Systematic temperature-dependent growth studies of TiC nanorods produced from spatially separated Ti metal and carbon nanotubes in the presence of iodine have shown that reaction proceeds initially via th…
Spectral data for HCOOH oxidation at Pt(111), Pt(100), and Pt(110) are presented and discussed. Spectra were taken shortly after the surfaces were contacted with a 0.1 M HCOOH/0.1 M HClO 4 solution at a controlled potential of 0.05 V vs RHE and give information on the adsorption and oxidation processes at the early st…
Disjoining pressure isotherms for foam films made from a nonionic surfactant, octyl β-glucoside, are measured at different surfactant concentrations, ionic strengths, and solution pH values. Below the cmc an electrostatic double-layer repulsion is present and dominates the long-range interaction. The decay length of t…
Tetrahedral Al-containing MCM-41, prepared under ambient conditions, exhibits suitable catalytic properties for the conversion of low-density polyethylene into hydrocarbon feedstocks.
It has been found that mesoporous structures of MCM-41 and MCM-48 disintegrate readily in distilled water around 370 K, while the structures can be stable in 100%-steam of 1 atmospheric pressure at much higher temperatures around 820 K. Thus, the structure disintegration is thermodynamically more favorable in water th…
Recent studies of molecular orientation in sheared liquid crystalline polymers have often yielded contradictory results. To check the self-consistency of methods for quantitative measurements of molecular orientation, liquid crystalline solutions of (hydroxypropyl)cellulose [HPC] and poly(benzyl glutamate) [PBG] have…
New hybrid organic–inorganic materials are prepared by hydrolysis and polycondensation, or cocondensation with tetraethyoxysilane, of iron porphyrins bearing a trifluorosily function; despite their insolubility, these ‘metalloporphyrinosilicas’ are efficient catalysts for alkene epoxidation by PhiO or ButOOh and alkan…