bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface characterization of hemodialysis membranes based on electrokinetic measurements
Authors: Werner Carsten , Jacobasch Hans‐Jörg 
Published: March 2011

AbstractHemodialysis membranes were characterized by means of streaming potential measurements. By variation of the concentrations of different ionic species in the measuring solutions surface potential determining processes can be distinguished: The investigated materials (cellulose derivates) yield surface charges mainly from preferred adsorption of ions. A thermodynamic model of the electrochemical double layer according to STERN (1) was applied to quantify that processes; the resulting set of parameters provide a conjunction between chemical surface properties and the observed interfacial charging processes.Streaming potential measurements can be used for the in situ characterization of the adsorption of biologically relevant molecules like proteins and polysaccharides onto membrane materials. The results given here show the alteration of interfacial properties of different cellulosic membranes through adsorption of human serum albumin and fibrinogen in single, sequential and competitive adsorption.
Crosslinked poly(ethylene oxide) for drug release systems
Authors: Panayotov Ivan M. , Belcheva Nadya , Stamenova Rayna , Tsvetanov Christo , Lambov Nikolai , Tsankov Stanislav , Smid Johannes 
Published: March 2011

AbstractThree types of poly(ethylene oxide) (PEO)‐ based hydrogels have been synthesized and studied for drug release applications: γ‐irradiated high molecular weight PEO, biodegradable polyether‐polyester networks with malic acid as crosslinker of poly(ethylene glycol)s and amphiphilic PEO‐based polyureas crosslinked with multifunctional isocyanates. Varying the length of the PEO chain and the type of the crosslinker, hydrogels with different swelling properties, loading capacities and release characteristics were obtained. A large number of pharmaceuticals (acebutolol. HCl, diclofenac. Na, procaine. HCl, phenobarbital.a, propranolol, etc.) were tested for a sustained release in different media (pH=1.2, 6.5, 7.4). Most of them # gave reasonable retarded release profiles for 8 hours when incorporated before the γ‐irradiation crosslinking of PEO. While amphiphilic hydrogels were found to be suitable for hydrophobic solutes, the biodegradable PEO‐based polyester ones affected predominantly the release of water‐soluble drugs. No pH effect was found for the γ‐irradiated PEO as a carrier in contrast to the strong pH dependence for the degradable polyester networks.
The structure and morphology of some mesophase polymers with flexible and stiff macromolecules
Authors: Platé Nikolai , Shklyaruk Boris , Kuptsov Sergei , Zadorin Alexei , Antipov Evgenii 
Published: March 2011

AbstractComparative analysis of the temperature behavior and phase composition of linear flexible‐chain polyfluoroalkoxyphosphazene and linear stiff‐chain copolyester was carried out using X‐ray diffraction at elevated temperatures and DSC measurements. The main idea of the study was to examine the nature of noncrystalline phases of such mesomorphic materials and to identify their structure and specific features of the morphology. The data obtained show that both flexible‐and stiff‐chain polymers despite the fact, whether their macromolecules contain or not contain mesogenic groups, are able to form columnar mesophases, whereas the formation of typically LC nematic and smectic states is the inherent structural feature only of stiff‐chain polymeric systems, which exhibit peculiar aperiodic layer structures.
Phase behaviour and morphology from a current viewpoint
Authors: Keller Andrew 
Published: March 2011

AbstractThe presentation is to give an overview of polymer morphology from the standpoint of recent developments with emphasis on the underlying phase transformations. In the latter context it is essential to recognize that with the exception of special systems having complex equilibrium surfaces, the conventionally considered morphology represents a non‐equilibrium state, hence a metastable state of matter arising from phase transformation having been arrested at some stage before the transformation was complete. In respect to the term ‘complete’ distinction needs to be made between completeness of material conversion and attainment of the equilibrium phase size and shape, a distinction which acquires special significance in polymeric systems as will be illustrated and discussed.
Perspective in polymer science and technology
Authors: Martuscelli Ezio 
Published: March 2011

AbstractScientific, and technological developments of polymers will tend to increase their attitude to substitute different materials (ceramics, metals, glasses. wood). Substitution and penetration process of polymers will follow different routes mostly having as objective the realization of systems specific functions suitable then to be more and more market oriented. The possibilities to realize these goals will require strong efforts of basic and applied research.
Crystal nucleation in an electric field
Authors: Ziabicki Andrzej , Jarecki Leszek 
Published: March 2011

AbstractNucleation of polar and apolar crystals in an electrostatic field has been analyzed. The analysis is based on the extended nucleation theory which takes into account orientation of amorphous kinetic elements and the resulting crystals. In an electric field free energy of transformation is orientation‐dependent which leads to orientation and field effects in thermodynamic (critical crystallization temperature) and kinetic crystallization characteristics (thermal and athermal nucleation rates).
Effect of surface treated fillers on the flow behavior and morphology of an immiscible blend. System: Polycarbonate/polypropylene
Authors: Rodriguez Yajaira , Ishida Hatsuo 
Published: March 2011

AbstractSurface treated fillers are added to an immiscible blend to study their effect on the melt behavior. The system studied is polycarbonate (PC)polypropylene (PP)/glass beads. Glass beads with no treatment, treated with an aminosilane and treated with a fluorosilane coupling agent are used. Differences in morphology are correlated with results from dynamic mechanical analysis. An increase in the viscosity of the blends filled with the amino‐silane agent, their response to different frequencies, and their activation energies for flow are related to a tendency toward compatibilization. Construction of master curves of viscosity data shows some potential as a compatibility criterion for these systems.
Dispersion of components and structure of elastomer system
Authors: Slusarski Ludomir 
Published: March 2011

AbstractElastomer systems as a rule are composed of several ingredients dispersed or dissolved in the matrix. The main components are: crosslinking substances, accelerators, activators, fillers mineral and/or organic, softeners and antioxidants. A random distribution of above mentioned components and also structural elements of a network formed are usually postulated [1]. From the results of investigations performed in our laboratory it follows that this approach in some cases is oversimplified. The problem is illustrated by few examples and some of its aspects are discussed.
Multicomponent lb films containing pre‐formed poly(3‐n‐Alkylthiophenes)
Authors: Sworakowski Juliusz , Bieńkowski Marcin , Chyla Antoni , Kucharski Stanisław 
Published: March 2011

AbstractThe paper reports on the deposition of two‐component Langmuir‐Blodgett films containing poly(3‐n‐alkylthiophenes) with “film‐builders” —low‐molecular‐weight amphiphilic molecules facilitating film formation. Fatty acids and 3‐n‐octadecylpyrrole were used as builders. The thicknesses and electric permittivities of the films were determined by measurements of the surface plasmon resonance; it was found that the former parameter is controlled by the length of the builder molecules. The electrical conductivities of the deposited films were of the order of 1 μS/m. The contact with oxides gives rise to an abrupt increase of conductivity by several orders of magnitude, followed by a decrease due to an irreversible destruction of the π‐electron system of the polymer.
Superconducting organic polymer films
Authors: Ulański J. , Jeszka J. K. , Laukhina E. , Helberg H. W. 
Published: March 2011

AbstractA concept of producing superconducting composites by means of reticulate doping of polymers with low molecular weight organic superconductors is presented. The obtained polycarbonate films contain around 2 wt.% of BEDT‐TTF polyiodides in a form of continuous crystalline network. D.c. and microwave conductivity measurements demonstrate, that the as‐obtained reticulate composites show semiconducting‐type properties. After annealing at optimized conditions a dramatic change occurs and the composites become metallic in the entire temperature range due to a conversion of various phases of the BEDT‐TTF polyiodides into the metallic and superconducting β1‐phase. The composites show the superconducting transition below 5 K1 as evidenced by magnetoresistance measurements, indicating that the content of the β1‐phase microcrystals in the conducting network exceeds the percolation threshold.
Opto‐electronic properties of conjugated polymers
Authors: Bässler Heinz 
Published: March 2011

AbstractThere is growing evidence, both theoretical and experimental, that the primary optical excitations in conjugated polymers are of excitonic nature. They are formed instantaneously upon photoexcitation and migrate incoherently among chain segments differing in length and, concomitantly, in excitation energy. Migration is associated with spectral relaxation manifest in the occurrence of a dynamic Stokes shift. Time‐resolved photoluminescence as well as energy transfer studies support this conceptual framework. In systems of the polyphenylenevinylene family the exciton binding energy is estimated to be about 0.4 eV, comparable to that in polydiacetylenes. However, transfer of a charge from an excited chain segment to neighboring chain segments costs less energy. Taking into account that all energy levels are disorder broadened this ensures that a fraction of excitations will find it energetically more favorable to decompose into an electron‐hole pair on adjacent chains (off‐chain or indirect exciton) that acts as precursor for photoconduction. Exciton breaking can be stimulated by a strong electric field as documented by cw and time resolved spectroscopy. Recent fluorescence as well as pump and probe measurements on a ladder type polymer (LPPP) with 150 fs time resolution will be reported which support the above conceptual framework and document the occurrence of stimulated emission.
Different sulphation degree and biological performance of hyaluronic acid as heparin‐like molecule
Authors: Barbucci Rolando , Magnani Agnese , Lamponi Stefania , Casolaro Mario 
Published: March 2011

AbstractHyaluronic acid was sulphated and seven derivatives, containing a different number of sulphated groups per disaccharide unit, were prepared (HyalSx, where x can be I, 2,2.5,3,3.5,3.8,4).The behaviour of the sulphated hyaluronic acids was studied at different pH's by using several thermodynamic and spectroscopic techniques. The ability of these macromolecules to form Cu2+ complexes in aqueous solution was also investigated.The sulphated hyaluronic acids were studied as heparin‐like molecules, thus coagulation and angiogenesis in‐vitro tests were performed. The influence of the degree of sulphation on the biological activity is well documented.
Metalloporphyrin heterodimers, molecular bilayer fibers and monolayer leaflets
Authors: Fuhrhop Jürgen‐Hinrich , Endisch Claus , Bindig Uwe , Rosengarten Bianca , Böttcher Christoph , Siggel Ulrich , Tsuchida Eishun , Komatsu Teruyuki 
Published: March 2011

AbstractAmphiphilic metalloporphyrins assemble in water to form supramolecular fibers, which have been characterized by transmission electron microscopy. Loose octopus porphyrin fibers can be doped with hydrophobic electron acceptors, metalloporphyrin monomolecular sheets are crystalline. Charge separation occurs in amino porphyrin fibers without added electron acceptors. Bolaamphiphilic porphyrins with four pyridinyl or methyl pyridinium groups in β‐pyrrolic positions have been synthesized. The regioisomer mixture is very soluble in water (≌ 0.1 M) and is ideally suited to form heterodimers with negatively charged ms‐tetrasubstituted porphyrins. Bimetallic porphyrinate pairs are described. The zinc complex is stable down to pH 1.0. Regioisomer II forms well‐defined molecular monolayer leaflets in bulk water at pH 2.5. The surface structure of such monolayers is discussed. It consists of a large cationic plane and hydrophobic edges. Possible applications are discussed shortly.
Colloidal metal dispersions and metal complexes in hydrocarbons
Authors: Hirai Hidefumi 
Published: March 2011

AbstractStable dispersions of colloidal metals in hydrocarbons have been prepared by a novel phase‐transfer method. The metals were gold, silver, palladium and ruthenium; the hydrocarbons were n‐hexane, cyclohexane and benzene. The phase transfer of colloidal metal particles from an aqueous phase to a hydrocarbon phase was achieved by adding salt to the emulsion of hydrocarbon in the aqueous suspension of metal with sodium oleate. The salts were sodium chloride, magnesium chloride, sodium sulfate, etc. The size distributions of the metal particles in the resulting hydrocarbon suspensions were almost the same as that of the original aqueous suspension. The dispersions of colloidal metals in hydrocarbons were stable for a long period of time without the addition of hydrocarbon‐soluble stabilizer. The critical phase‐transfer concentrations of various salts were determined. The phase‐transfer powers of cations were larger than those of anions. Those of divalent and trivalent cations were exceedingly larger than that of the monovalent cation. The concentration of colloidal metal dispersed in hydrocarbon was achieved by using the phase‐transfer method.
Multielectron transfer process for molecular conversions: Oxidative polymerization with vanadium catalysts
Authors: Tsuchida Eishun 
Published: March 2011

AbstractMultielectron transfer plays an important role in many chemical reactions. A collection of studies on metal complexes which exhibit one‐step multielectron transfer processes and on chemical reactions based on multielectron transfer systems is presented. Emphasis is placed on the role of multielectron transfer process as essential prerequisites for some molecular conversion systems such as the reduction of O2 and the oxidation of H2O. As an important example of molecular conversion, oxidative polymerization of aromatic compounds through two‐electron transfer is also reviewed.
The mineralization of CO32− ions on chitin‐ or chitosan‐ metal composite beads in water
Authors: Hirano Shigehiro , Yamamoto Ko‐Ichi , Inui Hiroshi , Ji Ming , Zhang Min 
Published: March 2011

AbstractThe following dry composite beads (diameter 1.0‐1‐2 mm) were prepared: chitin‐CaCO3, chitosan‐CaCl2. chitosan‐CuCl2, partially N‐acetylated chitosan‐CuCl2, chitosan‐CuSO4, chitosan‐Fe3O4, chitin‐SiO2. Each of chitosan‐CuCl2, chitosan‐CuSO4 and chitin‐CaCl2 composite beads was treated in aqueous K2CO3 at room temperature to afford a mixture of metal carbonates and hydroxides on chitin or chitosan chain.
Study on catalytic properties of the macromolecules containing pendant pyridine groups‐supported rhodium complexes for the carbonylation reactions
Authors: Jiang Dazhi , Li Xiaobao , Wang Enlai 
Published: March 2011

AbstractThe experiments reveal that anchoring rhodium(I) macromolecules containing pendant pyridine groups exhibit remarkably different carbonylation catalytic behaviours, depending on the quaternary degree of polymer ligands. The catalysts with the quaternized ligands are more active than that with the non‐quaternized ligands, but the best of the lots isn't the highestly quaternized. A new structural type of the compounds called the polydentate hetero‐bound rhodium(I) ion complexes is recognized to be responsible for higher carbonylation reactivities.
Synthesis of metal‐complexes and their reactivities: ‐The difference of reactivities among the manganese complexes‐
Authors: Kurusu Yasuhiko 
Published: March 2011

AbstractManganese chelates were prepared and the autoxidation of isopropyl benzene (IP) was carried out. (Mn‐Chelate‐1) showed a long induction period, but the other complexes (Mn‐Chelate‐2 and −3) which contain two or more magnesium ions in each molecule had shorter induction periods. The difference comes from the conformation around the manganese ion. Mn(III) acetate prepared from the oxidation of manganese (II) acetate with potassium permanganate in acetic acid was discussed.
Reaction conducted under rather severe conditions for a colloidal catalyst ‐ hydroformylation of propylene catalyzed by polymer‐protected rhodium colloids
Authors: Han Ming , Liu Hanfan 
Published: March 2011

AbstractHydroformylation of propylene has been conducted by a polymer‐protected rhodium colloid catalyst with an activity of 130 mol butanal / g atom Rh·h. The neat colloid catalyst is stable enough for repeated use for 7 times lasting ∼50 h under the reaction condition (temperature: 363 K, pressure: 40 bar) with a total TON of 5,065 cycle / atom Rh.
X‐Ray absorption studies of NiBr2(PEO)8 and ErBr3(PEO)12 complexes
Authors: McBreen J. , Yang X. Q. , Lee H. S. , Okamoto Y. 
Published: March 2011

AbstractX‐ray absorption studies of the poly(ethylene oxide) (PEO) complex NiBr2(PEO)8 show the formation of Br bridged dimers and higher aggregates. The Ni is complexed with Br and also with O atoms from the PEO. Aggregate formation increases with increasing temperature. In the case of ErBr3(PEO)12 the Er is simply complexed with Br and O. There is no evidence of aggregate formation.
Specific oxygen‐binding to a polymer‐supported N, N‐disalicylidenethylenediaminocobalt complex
Authors: Nishide Hiroyuki , Soda Eiichi , Mizuma Hiroyuki , Tsuchida Eishun 
Published: March 2011

AbstractA polymer membrane containing N,N‐disalicylidenethylenediaminocobalt (Co(salen)) was prepared. The Co(salen) supported in the polymer not only worked as a reversible and specific oxygen‐adsorbent but discontinuously bound oxygen at the atmospheric oxygen partial pressure of ca. 15 cmHg to give an on‐off‐like oxygen‐binding curve. Oxygen permeation through the Co(salen) membrane was also augmented in the higher upstream oxygen pressure region, which was caused by the specific oxygen‐binding to the Co(salen) fixed in the membrane.
Molecular design of ion and ion/electron mixed conducting polymers
Authors: Watanabe Masayoshi 
Published: March 2011

AbstractMethodology to design high performance ion and ion/electron mixed conducting polymers is briefly reviewed in this paper. In the case of ion conducting polymers based on polyethers, network polymers having dendritic side chains have been effective in terms of the achievement of high ionic conductivity and dimensional stability. Chemical modification of redox active sites to ion conducting polymers has realized ion/electron mixed conducting polymers even in the absence of fluid solvents. Electron transport mechanism in these mixed conducting polymers can be interpreted in terms of the bounded diffusion model presented by Savéant et al.
Synthesis of catalytically active polymer‐bound schiff base manganese complexes for selective epoxidation of unfunctional olefins
Authors: Du Xiangdong , Yu Xianda , Li Shuben 
Published: March 2011

AbstractAn unsymmetric tetradentate Schiff base with one vinyl group was first synthesized and copolymerized with styrene in toluene. Metalation of the copolymer with Mn(OAc)2 ·4H2O and LiCl‐H2O was quantitatively incorporated by the functional moiety determined by ICP‐AES technology The linear polymer‐bound manganese complexes were used in homogeneous condition as catalysts in acetonitrile for selective epoxidation of unfunctional olefins(i.e. styrene, α ‐methylstyrene and cyclohexene) at room temperature in the presence of iodosylbenzene (PhIO) as the terminal oxidant. The efficacy of epoxidation using the polymeric catalysts was comparable to the monomolecular analogs. Polymer effect was discussed.
Application of multifunction group‐containing ion exchange fibres for purification of waste water
Authors: Zhang Bao‐wen , Zhang Dao‐ling , Ge Xiao‐Peng , Miao Feng‐Qin 
Published: March 2011

AbstractThe multifunction groups‐containing ion exchange fibre is an amphoteric ion exchanger. It has high sorption capacities and good kinetic properties for the extraction of heavy metals. It might be an effective tool for removal and concentration of copper, cadmium, chromium, cobalt, nickel, lead, mercury, zinc and manganese.
Interfacial properties of glassy polymer melts: A Monte Carlo study
Authors: Baschnagel Jörg , Binder Kurt 
Published: March 2011

AbstractThe properties of the interface between a polymer melt and a solid wall are studied over a wide range of temperatures by dynamic Monte Carlo simulations. It is shown that in the supercooled state near the glass transition of the melt an “interphase” forms, the structure of which is influenced by the wall. The thickness of this interphase is determined from the monomer density profile near the surface and is strongly temperature dependent. At low glass‐like temperatures it is larger than the bulk radius of gyration of the chains.
Side‐chain crystallization induced in amorphous polymers by charge‐transfer interaction
Authors: Bolsinger Michael , Brizzolara Davide , Tefehne Christof , Schneider Hans Adam 
Published: March 2011

AbstractIt is shown that crystallization of side‐chains of amorphous polymers can be induced by charge‐transfer interaction. This is illustrated for the 1:1 D/A blend of the donor poly[4‐(9‐carbazolyl)butyl methacrylate] with the low molecular crystalline rod‐like biacceptor 4, 4'‐di(bromobutoxy)‐3, 3', 5, 5'‐tetranitrobiphenyl. It is supposed that the charge‐transfer interaction results in a self assembling in the 1:1 D/A blend between the low molecular biacceptor and the donor carbazoyl side groups, discoupled by alkyl spacers from the amorphous methacrylic backbone. The crystallization in the D/A blend is illustrated by optical microscopy, DSC and by the WAXS, the latter confirming the new crystalline structure of the 1:1 D/A blend, different from the crystalline structure of the low molecular biacceptor. Comparative molecular simulation of the most probable conformation of respective 10 repeating units indicates an extension of the backbone in the D/A blend, expressed by an substantial increase of the end‐to‐end distance. At the same time the tendency for a helicoidal arrangement and stacking of the D/A complexed side‐groups is suggested by the simulation, using the amorphous builder modul of Cerius2 1.5.
Nanodispersed metal and metal oxide particles in polymeric matrices from polyacrylonitrile precursors
Authors: Bronstein Lyudmila M. , Valetsky Pyotr M. , Solodovnikov Stanislav P. , Seregina Marina V. , Register Richard A. 
Published: March 2011

AbstractTwo ways of the colloid formation of metals and metal oxides in the polyacrylonitrile (PAN) and its copolymer (1.5 wt % of itaconic acid) (PAN‐I) have been studied. The thermal decomposition of W, Mo and Cr carbonyl complexes with PAN, prepared by the interaction of PAN nitrile groups with VI B group metal hexacarbonyls has been investigated. The thermolysis under air leads to a formation of metal oxide particles. For the Cr‐containing PAN, the presence of dispersed Cr2O3 with a size less than 3 nm was estimated by ESR. Co‐containing polymers were prepared by mixing Co2(CO)8 with PAN‐I in DMF. It was found that Co2(CO)8 interacts with DMF giving salt [Co(DMF)6]2+[Co(CO)4]‐2. By ferromagnetic resonance and SAXS, colloid size depends on thermolysis conditions and loading of the Co complex and varies from 1 to 10 nm.