Materials Literature
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A monolayer of poly( l -lysine) (PL) is attached covalently via amide bonds to an alkanethiol self-assembled monolayer (SAM) on a gold surface. The amide bond is formed in two steps: the terminal carboxylic acid groups of an 11-mercaptoundecanoic acid (MUA) SAM are first activated to the N -hydroxysulfosuccinimide (NH…
The reduction of Ag + ions in ethanol when certain surfactants are also present in the solution is shown to take place, even in the total absence of light. The reduction process leads to dispersions of silver nanoparticles, which are stable for weeks, although they show a certain tendency to stick to glass walls. Seve…
We describe the preparation of a new set of amphiphilic block copolymers with well-defined molecular weights and block volume fractions. The synthesis of a variety of polyalkane−poly(ethylene oxide) block copolymers was accomplished by a new polymerization−hydrogenation sequence. Initially, anionic polymerization of e…
Low-melting point salts, the basis of industrially relevant ionic liquids, exhibit smectic A mesophases over extended temperature ranges.
The effect of using a realistic model for the electrostatic forces on the calculated structures of molecular crystals is explored by using atomic multipoles derived from an SCF 6-31G** wave function. This was tested on a wide ranging database of 40 rigid organic molecules containing C, H, N, and O atoms, including nuc…
The pyrolysis of four polyhedral oligomeric silsesquioxane (POSS) macromers, Cy 8 Si 8 O 11 (OH) 2, Cy 8 Si 8 O 11 (OSiMe 3 ) 2, Cy 6 Si 6 O 9, and Cy 8 Si 8 O 12 (where Cy = c -C 6 H 11 ) and two POSS−siloxane copolymers [Cy 8 Si 8 O 11 −(OSiMe 2 ) n O−] ( n = 1, oligomer average 5.4) has been studied in argon, nitro…
We examine the equilibrium properties of a starburst dendrimer. A simple Flory theory is developed for the dependence of the radius of gyration of the starburst on its generation. A self-consistent mean field model is solved numerically to verify the Flory theory predictions and elucidate the density profile within th…
The effects of molecular structure on the electronic structure and redox properties of a series of 22 systematically designed conjugated polyquinolines and polyanthrazolines are explored by cyclic voltammetry and spectroelectrochemistry on thin films. The measured electrochemical bandgap of the series of conjugated po…
-position have been prepared as modular components for building block applications. These dyes are stable, accessible, and have suitable spectroscopic features for use as porphyrin accessory pigments in light-harvesting arrays.
The modeling of processes involving multiple length scales is an area of pressing concern, especially in problems such as nanoidentation and crack tip dislocation activity. In these cases, there is more than one characteristic dimension with the nanometer scale arising due to the presence of extended defects such as d…
Conjugated conducting polymers constitute a subject of research lying at the interface between solid-state physics and molecular science. Electronic absorption and vibrational spectroscopies of doped conjugated polymers, whose ground states are nondegenerate, are reviewed from a viewpoint of molecular spectroscopy. Ra…
The experimentally observed asymptotic scaling φ ( L / D ) = constant, for the random packing volume fraction ( φ ) of rods with high aspect ratio ( L / D ), is shown to be the consequence of uncorrelated rod−rod contacts, the constant being equal to 〈 c 〉 = 5.4 ± 0.2 contacts per rod. The weak dependence of 〈 c 〉 on…
A series of bis(2-(3,4-ethylenedioxy)thiophene)-based monomers have been synthesized and fully characterized; specifically ( E )-1,2-bis(2-(3,4-ethylenedioxy)thienyl)vinylene (BEDOT-V), 1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene (BEDOT-B), 4,4‘-bis(2-(3,4-ethylenedioxy)thienyl)biphenyl (BEDOT-BP), 2,5-bis(2-(3,4-eth…
An FTIR and quadrupole mass spectroscopic study of CO adsorption and oxidation with 16 O 2 and 18 O 2 on copper supported on ZnO and TiO 2 is presented. The experimental results indicate that CO is adsorbed on the metallic particles dispersed on both oxides on two kinds of sites, on the normal terrace sites and on sit…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganic Reactions at Well-Defined Oxide SurfacesMark A. BarteauView Author Information Center for Catalytic Science and Technology, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716 Cite this: Chem. Rev. 1996, 96, 4, 1413–1430Publication Date…
This book documents the proceedings of the Fourth International Symposium on Polymer Surface Modification: Relevance to Adhesion held under the auspices of MST Conferences, LLC in Orlando, FL, June 9-11, 2003. Polymers are used for a variety of purposes in a host of technological applications and even a cursory look a…
Time-resolved fluorescence and absorption techniques have been used to investigate energy and photoinduced electron transfer in a covalently linked free-base porphyrin−fullerene dyad and its zinc analog. In toluene, the porphyrin first excited singlet states decay in about 20 ps by singlet−singlet energy transfer to t…
Interfacial effects play a major role in the formation of organic polymer−smectite clay nanocomposites. As little 2 mol % Na+ cations on the exchange sites of a short-chain alkylammonium smectite clay completely inhibits exfoliation of the silicate nanolayers in an epoxy matrix.
The properties of dendrimers (“starburst” molecules) under varying solvent conditions are studied using molecular dynamics simulations. The dendrimers are found to have a compact (space filling) structure under all solvent conditions, with a radius of gyration which scales with the number of monomers as R G ∝ N 1/3 .…
Many processes have been considered over the years to explain the origin of breakdown in cable insulation. Such effects as space charge build-up, tree growth, charge injection, etc. have all been discussed. Various techniques are now available to measure, in a nondestructive way, space charge distributions in insulato…