Materials Literature
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We investigate the spinodal decomposition of a polymer mixture, at both critical and off-critical compositions, using atomic force microscopy. Phase separation in the bulk is imaged using tapping mode on the surface of microtomed samples. The generated surface profiles, revealed in height images, are analyzed accordin…
A novel approach for photochemical definition of distinct, basic color, emission areas in thin polymeric films is introduced. Two-color, blue and green, fluorescence imaging is demonstrated using an amino diphenylhexatriene derivative that upon protonation shows sizable shifts in both absorbance and fluorescence spect…
Anionic and cationic block copolymers containing different fractions and chain lengths of poly(ethylene glycol) (PEG) blocks were synthesized and characterized. Polyelectrolyte complex (PEC) formation between these copolymers and homopolyelectrolytes and the stability of these complexes in salt solutions were studied…
A light scattering turbidity method has been employed to measure the dimensionless colloidal osmotic compressibility of carefully characterized model athermal colloid (silica)−polymer (polystyrene) suspensions. Mixture thermodynamics is controlled by purely repulsive, hard sphere interactions between the particles whi…
Adsorption/desorption of water in the mesoporous material MCM-41 was observed with neutron diffraction. Results obtained with a H 2 O/D 2 O mixture contrast-matched to the host material unambiguously show that the pores are fully hydrated in the presence of excess water. During desorption carried out by air-drying a s…
[reaction: see text] An unsymmetrical analogue of 3,4-ethylenedioxythiophene (EDOT) has been synthesized by transetherification of 3,4-dimethoxythiophene. Electropolymerization leads to a stable electroactive polymer with electrochemical and electronic properties intermediate between those of the two symmetrical paren…
Self-assembled (SA) films of octadecyltrichlorosilane were patterned by exposure to X-rays in air through a mask to produce chemically patterned surfaces. The irradiated regions of the SA films underwent surface chemical modification from nonpolar, hydrophobic surfaces to polar, hydrophilic surfaces. The degree of che…
The degradation of polystyrene in various Lewis acids [aluminum chloride, ferric chloride, boron triflouride etherate, and tin(IV) chloride] at different temperatures (75−125 °C) has been studied in this work. The evolution of the molecular weight distribution (MWD) has been modeled using continuous distribution kinet…
ADVERTISEMENT RETURN TO ISSUECommunication to the...Communication to the EditorNEXTThin-Film Differential Scanning Calorimetry: A New Probe for Assignment of the Glass Transition of Ultrathin Polymer FilmsM. Yu. Efremov, J. T. Warren, E. A. Olson, M. Zhang, A. T. Kwan, and L. H. AllenView Author Information Material S…
Microporous manganese oxides have been prepared by nonaqueous sol−gel reactions involving tetrabutylammonium (TBA) or tetraethylammonium (TEA) permanganate and methanol in the presence of alkali cation dopants. Layered birnessite-type materials were obtained for Na + and K + dopants in a 0.5:1 reactant ratio with mang…
A new class of triarylpyridinio-derivatized [4'-(p-phenyl)(n)]terpyridyl ligands, R(1)(2)R(2)TP(+)-(p)(n)tpy, was designed as a novel category of electron-acceptor (A)-substituted proto-photosensitizing molecules. The first elements of this versatile family of ligands (i.e., n = 0, 1 and R(1) = R(2) = H), H(3)TP(+)-tp…
Monolayers of a predominantly hydrophobic poly(styrene)- b -poly(ethylene oxide) copolymer (7% PEO by mass) were transferred to a silicon substrate using the Langmuir−Blodgett method. The films were imaged using atomic force microscopy, and three types of features were observed in various proportions: dots (circular a…
Chromium-containing wastes from various industrial sectors are under critical review. Leather processing is one such industrial activity that generates chromium-bearing wastes in different forms. One of them is chrome shavings, and this contributes to an extent of 10% of the quantum of raw skins/hides processed, amoun…
Adsorption of human serum albumin (HSA) onto conducting polypyrrole powders, doped with chloride (PPyCl), dodecyl sulfonate (PPyDS), and tosylate (PPyTS), has been monitored in 0.1 M phosphate buffer saline (PBS) and pH 7.4 using UV−visible spectroscopy in conjunction with the depletion method. The decreasing trend of…
Measurements of ultrafast fluorescence anisotropy decay in model branched dendritic molecules of different symmetry are reported. These molecules contain the fundamental branching center units of larger dendrimer macromolecules with either three (C(3))- or four (T(d), tetrahedral)-fold symmetry. The anisotropy for a t…
The self-assembly of alpha,alpha'-linked sexithiophenes with chiral and achiral penta(ethylene glycol) chains attached at the alpha-positions of the terminal rings, that is, 2,2':5',2'':5'',2''':5''',2'''':5'''',2'''''-sexithiophene-5,5'''''-dicarboxylic acid-2S)-2-methyl-3,6,9,12,15-pentaoxahexadecyl ester (1) and 2,…
The dehydroxylation/dehydration and Lewis acidity of the surface of monoclinic tungsten oxide (m-WO 3 ) powder as a function of evacuation temperature was investigated by infrared spectroscopy. At room temperature, the m-WO 3 surface contains both isolated and hydrogen bonded hydroxyl groups along with equal amounts o…
We present a new approach for numerical solutions of ab initio quantum chemistry systems. The main idea of the approach, which we call canonical diagonalization, is to diagonalize directly the second quantized Hamiltonian by a sequence of numerical canonical transformations.
It is demonstrated that thiols can adsorb to gold without losing hydrogen. Dodecyl sulfide-capped gold clusters have been prepared and subjected to ligand exchange reactions in perdeuterated benzene by addition of dodecanethiol and subsequently dodecyl disulfide. It is shown by 1H NMR spectroscopy that dodecanethiol m…
A synthesis strategy for the systematic control of the pore wall thickness has been developed for the mesoporous silicas with 2-D hexagonal order using ionic and nonionic surfactant mixtures. The mesoporous silicas have been used as templates for the synthesis of 2-D hexagonally ordered mesoporous carbons with control…