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Characterization of Starburst Dendrimers by EPR. 4. Mn(II) as a Probe of Interphase Properties

M. Francesca Ottaviani、Fabio Montalti、Maurizio Romanelli 等 5 位作者1996-01-01The Journal of Physical Chemistry

Mn(II) has been used as a probe to investigate the interacting abilities of the various ligand sites at the surface of starburst dendrimers (SBDs) at different protonation conditions, and as a function of generation ( G ), both for half- and full-generation SBDs ( n .5-SBDs and n -SBDs, respectively). The computer-aid…

Advanced Polymer Synthesis and CharacterizationFuel Cells and Related MaterialsDendrimers and Hyperbranched Polymers

Azo Polymers for Reversible Optical Storage. 9. Copolymers Containing Two Types of Azobenzene Side Groups

Mei-Sing Ho、Almeria Natansohn、P. Rochon1996-01-01Macromolecules

A series of copolymers with two structural units 1-(4-nitrophenyl)-2-(4-{[2-(methacryloyloxy)ethyl]ethylamino}phenyl)diazene (DR1M), which contains donor−acceptor substituents in the azobenzene group, and 4-[2-(methacryloyloxy)ethyl]azobenzene (MEA), which has no donor−acceptor substituents was prepared. The maximum o…

Liquid Crystal Research AdvancementsPhotochemistry and Electron Transfer StudiesPhase-change materials and chalcogenides

Some properties of films cast from polyurethane aqueous dispersions of polyether-based anionomer extended with hydrazine

Fernanda M. B. Coutinho、Marcia C. Delpech1996-01-01Polymer Testing

Polyurethanes as aqueous dispersions were synthesized and some mechanical properties of the casted films were analysed. Anionomers prepolymers were prepared in bulk by the reaction of poly(propylene oxide), 4,4′-dicyclohexylmethane diisocyanate and dimethylolpropionic acid. The acid group's neutralization was carried…

Polymer Nanocomposites and PropertiesPolymer composites and self-healingEpoxy Resin Curing Processes

Dynamical criterion for two-dimensional freezing

Hartmut Löwen1996-01-01Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

The dynamical criterion for freezing of three-dimensional colloidal fluids recently proposed by L\"owen, Palberg, and Simon [Phys. Rev. Lett. 70, 1557 (1993)] states that the ratio of the long-time to short-time self-diffusion coefficients has the universal value 0.1 along the fluid freezing line. Based on Brownian dy…

Material Dynamics and PropertiesSpectroscopy and Quantum Chemical StudiesAdvanced Thermodynamics and Statistical Mechanics

Self Consistent Field Calculations of Interactions between Chains Tethered to Spherical Interfaces

Eric K. Lin、Alice P. Gast1996-01-01Macromolecules

Self consistent mean field (SCF) theory is used to investigate the structure of and interactions between layers of polymer chains tethered to a spherical interface. Traditional methods have combined flat geometry results with the Derjaguin approximation to calculate the interaction potentials between curved surfaces,…

Polymer Surface Interaction StudiesForce Microscopy Techniques and ApplicationsAdhesion, Friction, and Surface Interactions

The porphyrinogen–porphyhrin relationship: the discovery of artificial porphyrins

Carlo Floriani1996-01-01Chemical Communications

The oxidation of meso-tetrahydrotetraalkylporphyrinogen, which is the chemical and biochemical precursor of porphyrins, has been reexamined using meso-octaalkyl-porphyrinogen as a model compound. This investigation has led to the discovery of oxidized forms of porphyrinogen other than porphyrins, which we call artific…

Porphyrin and Phthalocyanine ChemistryMetal-Catalyzed Oxygenation MechanismsPorphyrin Metabolism and Disorders

Plasma surface modification of polyimide for improving adhesion to electroless copper coatings

G. Rozovskis、J. Vinkevičius、Janė Jačiauskienė1996-01-01Journal of Adhesion Science and Technology

The influences of oxygen plasma treatment of polyimide (PI) films on the adhesion of electroless copper coatings as well as on the chemical composition of the film surface and the PI surface morphology were investigated. The plasma operating parameters were 1800 W forward power with O2 flowing at a rate of 300 cm3/min…

Electronic Packaging and Soldering TechnologiesSynthesis and properties of polymersTribology and Wear Analysis

Characterization and modeling of metal-film microbolometer

Jin‐Shown Shie、Yeong-Maw Chen、Mang Ou‐Yang 等 4 位作者1996-01-01Journal of Microelectromechanical Systems

The characteristic thermal parameters of a platinum-film microbolometer are extracted from the data of two measuring methods. A simple and accurate equivalent circuit model, along with its thermal behavior, is proposed for the device. Applying the model to simulate some device circuits results in good agreement with t…

Advanced MEMS and NEMS TechnologiesTransition Metal Oxide NanomaterialsAdvanced Sensor Technologies Research

Polyelectrolytes Grafted to Curved Surfaces

Ekaterina B. Zhulina、Oleg V. Borisov1996-01-01Macromolecules

We present a scaling theory to describe equilibrium conformations of weakly charged polyelectrolyte molecules grafted at one end onto impermeable surfaces of various morphologies (spheres, cylinders) and of arbitrary curvature. We focus on the case of sufficiently densely grafted chains, i.e., on curved polyelectrolyt…

Surfactants and Colloidal SystemsPolymer Surface Interaction StudiesElectrostatics and Colloid Interactions

Modeling of the Salt and pH Effects on the Permeability of Grafted Porous Membranes

Kyösti Kontturi、Salvador Mafé、José A. Manzanares 等 5 位作者1996-01-01Macromolecules

A simple theoretical model describing the effects of pH and salt concentration on the permeability and counterion transport number of variable permeability membranes has been presented and validated experimentally for the case of poly(vinylidene fluoride) membranes graft modified with poly(acrylic acid) chains by radi…

Membrane Separation TechnologiesHydrogels: synthesis, properties, applicationsPolymer Surface Interaction Studies

An investigation on the impact fracture characteristics of EPR toughened polypropylene

Wing Yip Tam、T. Cheung、Robert K.Y. Li1996-01-01Polymer Testing

The effect of adding ethylene-propylene copolymer (EPR) into polypropylene (PP), with particular emphasis on the impact fracture characteristics, will be presented in this work. The impact fracture characterization techniques used include the notched Izod impact strength, drop-weight dart impact, and the impact fractu…

Mechanical Behavior of CompositesPolymer crystallization and propertiesNatural Fiber Reinforced Composites

Highly ordered materials with ultra‐low surface energies: Polyelectrolyte–surfactant, complexes with fluorinated surfactants

Markus Antonietti、Susanne Henke、Andreas F. Thünemann1996-01-01Advanced Materials

Are non‐stick surfaces “the chemical analogue of the perpetual motion machine”, i.e., unattainable? Cheap and simple‐to‐produce systems with ultra‐low surface energy—and so on the way towards this ideal—are polyelectrolyte–surfactant complexes. Polarization micrographs of such systems involving fluorinated surfactants…

Surface Modification and SuperhydrophobicityBlock Copolymer Self-AssemblyAdhesion, Friction, and Surface Interactions

“Log-Rolling” Alignment in Main-Chain Thermotropic Liquid Crystalline Polymer Melts under Shear: An In-Situ WAXS Study

Angel Romo‐Uribe、Alan H. Windle1996-01-01Macromolecules

This paper sets down in detail the observation, first announced as a note (Romo-Uribe, A.; Windle, A. H. Macromolecules 1993, 26, 7100), of a strident and reversible orientation transition in a specially synthesized series of thermotropic random copolyester melts of the Vectra A900 type. The transition is between the…

Liquid Crystal Research AdvancementsRheology and Fluid Dynamics StudiesAdvanced Materials and Mechanics

Pattern Forming Instability in Homeotropically Aligned Liquid Crystals

Shoichi Kai、Ken Hayashi、Yoshiki Hidaka1996-01-01The Journal of Physical Chemistry

The electrohydrodynamic pattern forming instability (EHC) driven by an ac voltage applied to a homeotropically aligned nematic liquid crystal layer is experimentally studied near onset. By controlling an external magnetic field, many different scenarios become accessible. For finite fields various regular convective s…

Liquid Crystal Research AdvancementsNonlinear Dynamics and Pattern FormationPlant Reproductive Biology

Interpretation of the Binding Energy and Auger Parameter Shifts Found by XPS for TiO2Supported on Different Surfaces

José A. Mejías、Víctor Jiménez、G. Lassaletta 等 6 位作者1996-01-01The Journal of Physical Chemistry

In this paper the deposition of very thin films of TiO 2 on different substrates (SiO 2, MgO, Ag) is studied by XPS. Shifts in the Ti 2p BE and the Auger parameter of Ti (α‘ = Ti 2p BE + Ti L 3 M 23 V Auger KE) are observed on the three substrates. The magnitude and the sign of the shifts with respect to those of bulk…

ZnO doping and propertiesCatalytic Processes in Materials ScienceElectron and X-Ray Spectroscopy Techniques

DMTA and FTIR Investigation of the Phase Behavior of Poly(methyl methacrylate)−Poly(4-vinylphenol) Blends

Dean Li、Josée Brisson1996-01-01Macromolecules

The phase behavior of poly(methyl methacrylate) (PMMA)/poly(4-vinylphenol) (PVPh) blends was investigated using differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), small-angle X-ray scattering (SAXS), and Fourier transform infrared (FTIR) spectroscopy. Only one glass transition was obs…

Polymer crystallization and propertiesMaterial Dynamics and PropertiesPolymer Nanocomposites and Properties

Self-Assembly of Ribbons and Frameworks Containing Large Channels Based upon Methylene-Bridged Dithio-, Diseleno-, and Ditelluroethers

Jane R. Black、Neil R. Champness、William Levason 等 4 位作者1996-01-01Inorganic Chemistry

Homoleptic copper(I) and silver(I) complexes [M(n)(L-L)(2)(n)()](BF(4))(n)() (M = Cu or Ag; L-L = MeECH(2)EMe; E = S, Se or Te) have been prepared and characterized by analysis, FAB mass spectrometry, and IR and multinuclear NMR spectroscopy ((1)H, (77)Se, (125)Te, (63)Cu and (109)Ag). The single-crystal X-ray structu…

Organometallic Complex Synthesis and CatalysisMetal complexes synthesis and propertiesMagnetism in coordination complexes

Ab Initio CI Determination of the Exchange Coupling Constant of Doubly-Bridged Nickel(II) Dimers

O. Castell、Rosa Caballol、Víctor Manuel Pérez García 等 4 位作者1996-01-01Inorganic Chemistry

Ab initio DDCI2 (difference-dedicated configuration interaction) calculations are performed on the exchange coupling constant of the doubly-bridged Ni(II) complexes [Ni(en)(2)Cl](2)(2+) and [Ni(terpy)(N(3))](2)(2+), which are modeled by substituting the external ligands with ammonia groups. The variational CI space is…

Metal complexes synthesis and propertiesMagnetism in coordination complexesMetal-Catalyzed Oxygenation Mechanisms

Effect of Copolymer Architecture on the Interfacial Structure and Miscibility of a Ternary Polymer Blend Containing a Copolymer and Two Homopolymers

Mark Dadmun1996-01-01Macromolecules

The effect of copolymer architecture on the phase behavior of a ternary polymer blend containing two homopolymers and a copolymer as well as the interfacial characteristics of this blend in the phase-separated state are examined using Monte Carlo simulation. At low copolymer concentration ( ca . 1%), the phase transit…

Polymer crystallization and propertiesMaterial Dynamics and PropertiesBlock Copolymer Self-Assembly