Search results for "FILM"
showing 10 items of 4577 documents
‘Intrinsic’ profiles and capillary waves at interfaces between coexisting phases in polymer blends
2001
Abstract Lateral fluctuations in the local position of the center of the interface between coexisting phases in unmixed polymer blends lead to a broadening of interfacial widths; comparing self-consistent field predictions for the ‘intrinsic’ profile to simulations (or experiments), this ‘capillary wave’ broadening needs consideration. This problem has been studied by extensive Monte Carlo simulations of the bond fluctuation model for symmetrical polymer mixtures, both for free interfaces (between bulk phases) and for confined interfaces (in thin films between parallel walls). While the capillary wave predictions at large length scales are confirmed, the extraction of the ‘intrinsic’ profil…
Interfaces between coexisting phases of polymer mixtures: Comparison between Monte Carlo simulations and theoretical predictions
1997
Large scale Monte Carlo investigations of the interface between A-rich and B-rich phases of symmetric binary (AB) polymer mixtures are presented, using the bond fluctuation model of flexible chains with NA=NB=N=32 effective monomers. The temperature range studied, 0.144<T/Tc0.759, includes both the strong and the weak segregation limit. Interfacial free energy and interfacial structure are studied, and compared to predictions based on the selfconsistent field theory. Also the broadening of the interfacial width due to capillary waves is considered, and finite size effects due to the confinement of interfaces in thin films of polymer blends are discussed.
Ionic transport characteristics of negatively and positively charged conical nanopores in 1:1, 2:1, 3:1, 2:2, 1:2, and 1:3 electrolytes
2019
We study experimentally the current (I)-voltage (V) curves of 1:1, 2:1, 3:1, 2:2, 1:2, and 1:3 electrolytes in positively and negatively charged conically-shaped pores of nanoscale dimensions. The positive charges are poly(allylamine hydrochloride) chains functionalized on the pore surface by electrostatic interactions while the negative charges are carboxylic acid groups. Under physiological conditions, these fixed-charge groups are ionized and strongly interact with the different monovalent, divalent, and trivalent ions in the pore solution. The current rectification of the I-V curves and the membrane potentials provide fundamental information on the interaction of the pore charge groups …
A missing member in the family of chalcogenophene-substituted 2,2′:6′,2″-terpyridine: 4′-(tellurophen-2-yl)-2,2′:6′,2″-terpyridine, its Ru(II) comple…
2019
Abstract The new terpyridine derivative 4’-(tellurophen-2-yl)-2,2′:6′,2″-terpyridine and its homoleptic Ru(II) complex have been prepared and characterized by different techniques (NMR, UV–Vis, mass spectrometry). Additionally, a thin polymer film was obtained through electrochemical oxidation and coupling of tellurophene moieties. The obtained organic coating showed very interesting electrochemical and electrochromic properties, thanks to its Ru(terpy)2 groups.
Ejection of molecules from WO3 under ion bombardment: the role of the crystal structure
1992
Abstract Emission of molecular ions from WO 3 and Na x WO 3 was studied by SIMS. It was found that the phenomenon of ejection of molecules had not arisen from specific WO bond lengths and strengths in tungsten trioxide.
1,1-Dichloroethane: a molecular crystal structure without van der Waals contacts?
2008
Isochoric and isobaric freezing of 1,1-dichloroethane, CH3CHCl2, mp = 176.19 K, yielded the orthorhombic structure, space group Pnma, with the fully ordered molecules, in the staggered conformation, located on mirror planes. The CH3CHCl2 ambient-pressure (0.1 MPa) structures were determined at 160 and 100 K, whereas the 295 K high-pressure structures were determined at 0.59 and 1.51 GPa. At 0.1 MPa, all intermolecular distances are considerably longer than the sums of the van der Waals radii, and only a pressure of about 1.5 GPa squeezed the Cl···Cl and Cl···H contacts to distances commensurate with these sums. The exceptionally large difference between the melting points of isomeric 1,1- a…
Scanning tunneling microscopy investigation of tricycloquinazoline liquid crystals on gold
2000
Self-assembled monolayers (SAMs) of hexaalkylthioether derivatives of tricycloquinazoline (TCQ) on Au(111) and tungsten diselenide (WSe2) were investigated by scanning tunneling microscopy (STM). The Au(111) surfaces were found to be etched by the thioether containing solutions. Corroded surfaces which are similar to gold surfaces that were coated with SAMs of thiols or disulfides were revealed by STM. Atomic adsorption spectroscopy proved that an amount of gold that corresponds to ca. 30% of a monolayer was dissolved in the assembly solutions. On gold, the aromatic cores of the molecules were found to be in face-on orientation. The alkyl substituents were in most cases folded upwards and s…
Buildup of ultrathin multilayer films by a self-assembly process: III. Consecutively alternating adsorption of anionic and cationic polyelectrolytes …
1992
A solid substrate with a positively charged planar surface is immersed in a solution containing an anionic polyelectrolyte and a monolayer of the polyanion is adsorbed. Since the adsorption is carried out at relatively high concentrations of polyelectrolyte, a large number of ionic residues remain exposed to the interface with the solution and thus the surface charge is effectively reversed. After rinsing in pure water the substrate is immersed in the solution containing a cationic polyelectrolyte. Again a monolayer is adsorbed but now the original surface charge is restored. By repeating both steps in a cyclic fashion, alternating multilayer assemblies of both polymers are obtained. The bu…
Physico-chemical investigation of nanostructures in liquid phases: Nickel chloride ionic clusters confined in sodium bis(2-ethylhexyl) sulfosuccinate…
2009
The confinement of finite amounts of nickel chloride in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles dispersed in n-heptane has been investigated by FT-IR, UV-vis-NIR and fluorescence spectroscopies. The analysis of experimental data consistently leads to hypothesize that NiCl(2) forms small size ionic clusters stabilized by a monolayer of oriented surfactant molecules. Due to confinement and interfacial effects, these ionic clusters show peculiar photophysical properties, which are different from those possessed by the bulk material. From NiCl(2)/AOT/n-heptane solutions, by evaporation of the organic solvent, interesting salt/surfactant nanocomposi…
Electrochemical synthesis of sulfamides.
2021
Herein we demonstrate the first electrochemical synthesis protocol of symmetrical sulfamides directly from anilines and SO2 mediated by iodide. Sulfamides are an emerging functional group in drug design. Highlights are the direct use of SO2 from a stock solution and no necessity of any supporting electrolyte. Overall, the reaction has been demonstrated for 15 examples with yields up to 93%.