Search results for "FILM"
showing 10 items of 4577 documents
Homocoupling of terminal alkynes on calcite (10.4)
2018
Abstract On-surface synthesis has been identified as highly versatile strategy to prepare molecular structures on surfaces with single-atom precision. Inspired by the classical Glaser coupling, homocoupling of terminal alkynes has attracted great attention for on-surface synthesis. This coupling is known for providing a rigid and linear linkage, which is highly interesting for the synthesis of molecular wires. For molecular wire formation, non-conductive substrates are needed for electronic decoupling. So far, however, coupling of terminal alkynes has not been performed on a bulk insulator surface. Here, we present an atomic force microscopy study, indicating that 4,4″-diethynyl-[1,1′:4′,1″…
Effect of carboxymethyl cellulose concentration on rheological behavior of milk and aqueous systems. A creep and recovery study
2009
Carboxymethyl cellulose (CMC) is an anionic polysaccharide used mainly as stabilizer and thickener agent. The purpose of this study was to investigate the effect of CMC concentration on viscoelasticity of dairy and aqueous model systems through the analysis of creep and recovery tests. The viscoelastic properties of different concentrations of CMC (0.75, 1.00, 1.25, and 1.50% w/w) in two milk systems (skimmed milk and whole milk) were compared with those of the same concentration of biopolymer in aqueous solution. Creep curves were fitted to a six parameter mechanical model (Burger + Kelvin-Voigt), whereas an empirical equation was used for recovery. The creep and recovery properties of sam…
Micropatterning of neurons using organic substrates in culture
1997
Abstract In this study, we have used spatially defined surfaces of organic thin films to micropattern the outgrowth of central nervous system neurons in culture. Glass substrates were first chemically modified with synthetic peptides derived from an extra-cellular matrix protein laminin to couple a functionality that promotes a neuron-substrate interaction. The modification procedure was verified using X-ray photoelectron spectroscopy. The functionality of the modified glass surfaces was examined by growing neurons dissociated from mammalian central nervous tissues in culture. Spatially defined surfaces of the peptide were then fabricated by selectively attaching the peptide to coplanar sur…
Self-organization of amphiphilic N-acylated linear polyethyleneimines: investigation of a reversible monolayer collapse
1996
Abstract Poly-N-4-decyloxybenzoylethyleneimine, highly crystalline in bulk, forms a stable monolayer at the air-water interface which undergoes a reversible collapse into a probable bilayer structure at higher surface pressures. We achieved transfer both from the monolayer and “bilayer” region of the polymer film at the water surface onto hydrophilic and hydrophobized quartz supports. Based on X-ray investigations on the deposited Langmuir-Blodgett films, a possible mechanism for the reversible collapse is proposed.
A Combined Top-Down/Bottom-Up Approach for the Nanoscale Patterning of Spin-Crossover Coordination Polymers
2007
Molecular spin-crossover complexes of 3d–3d transitionmetal ions have been the focus of many researchers’ work because of their fascinating properties associated with the bistability of their electronic states (high spin (HS) or low spin (LS)). Although the origin of the spin-crossover phenomenon is purely molecular, the macroscopic behavior of these systems in the solid state is strongly determined by the interactions, of mainly elastic origin, between the transition-metal ions. Recently, remarkable progress has been made in the area of spin-crossover complexes with infinite one-, two-, or three-dimensional (1D, 2D, 3D) networks, the so-called coordination polymers. The purpose of this app…
Inside Front Cover: A Combined Top-Down/Bottom-Up Approach for the Nanoscale Patterning of Spin-Crossover Coordination Polymers (Adv. Mater. 16/2007)
2007
The background scanning electron microscopy image shows nanometric patterns of the 3D spin crossover coordination polymer Fe(pyrazine)[Pt(CN)4] (see schematic structure in the circle), which have been fabricated using a combination of lift-off and multilayer sequential assembly methods. These patterns, reported by Gabor Molnar, Azzedine Bousseksou, and co-workers on p. 2163, exhibit a bistability of their electronic states (1A1 ⇌ 5T2), and thus represent a novel platform for a wide array of potential applications.
Magnetic Composite Thin Films of FexOy Nanoparticles and Photocrosslinked Dextran Hydrogels
2012
Abstract Magnetic hydrogel composites are promising candidates for a broad field of applications from medicine to mechanical engineering. Here, surface-attached composite films of magnetic nanoparticles (MNP) and a polymeric hydrogel (HG) were prepared from magnetic iron oxide nanoparticles and a carboxymethylated dextran with photoreactive benzophenone substituents. A blend of the MNP and the dextran polymer was prepared by mixing in solution, and after spin-coating and drying the blend film was converted into a stable MNP–HG composite by photocrosslinking through irradiation with UV light. The bulk composite material shows strong mobility in a magnetic field, imparted by the MNPs. By util…
Unmixing of Polymer Blends Confined in Ultrathin Films: Crossover between Two-Dimensional and Three-Dimensional Behavior
2006
The interplay between chain conformations and phase separation in binary symmetric polymer mixtures confined into thin films by "neutral" hard walls (i.e., walls that do not preferentially attract or repel one of the two components of the mixture) is studied by Monte Carlo simulations. Using the bond fluctuation model on a simple cubic lattice in the semi grand canonical ensemble, we locate the critical temperature of demixing via finite size scaling methods for a wide range of chain lengths (16/= N/= 256 effective monomers per chain) and film thicknesses (2/= D/= 19 lattice spacings). Simultaneously, we investigate the geometrical structure of the chains, showing that despite using melt de…
Electrical Voltage Control of the Pressure-Induced Spin Transition at Room Temperature in the Microporous 3D Polymer [Fe(pz)Pt(CN)4]
2019
Fine control and direct monitoring of the spin crossover properties driven by pressure at room temperature are reported for the porous three-dimensional coordination polymer {Fe(pz)[Pt(CN)4]} by us...
Electrooptic coefficient measurements by Mach Zehnder interferometric method: Application of Abelès matrix formalism for thin film polymeric sample d…
2013
Abstract In Mach–Zehnder interferometric (MZI) method for determination of thin organic film electrooptic ( EO ) coefficients r 13 and r 33 critical effects, like multiple internal reflections and sample thickness modulation due to electrostriction and piezoelectricity are usually overlooked. Ignoring these effects may lead to inaccurate calculation of EO coefficients from experimental data by the simplified equations. To describe the influence of the above mentioned effects on the output of a MZI containing a thin film polymer sample we have used the Abeles matrix formalism.