bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of interfacial adhesion between glassy polymers using the JKR method
Authors: Mangipudi Venkata S. , Huang Elbert , Tirrell Matthew , Pocius Alphonsus V.
Published: March 2011

The surface and interfacial energies of polymers are measured using the JKR‐type experiments. A novel method has been developed to prepare samples of glassy polymers for adhesion measurements. A thin layer of a polymer is coated on the surface of an O2‐plasma modified cross‐linked poly(dimethylsiloxane) [PDMS] spherical cap resulting in the formation of a composite. Using the JKR theory, the surface energies of polystyrene [PS] and poly(methyl methacrylate) [PMMA] are determined from the measurements of the contact radius as a function of applied load. The results of the JKR‐type experiments are compared to adhesion measurements done using the surface forces apparatus (SFA). Adhesion hysteresis was observed for PS‐PS contact as well as PMMA‐PMMA contact. However, no hysteresis was observed for PDMS‐PDMS, PDMS‐PS, and PDMS‐PMMA contacts. The exact origin of the hysteresis is not clear at present. The current evidence suggests that hysteresis is due to rearrangement of the interface during contact.
Approaches to supramolecular structures with various topologies in the crystal lattice
Authors: Valiyaveettil Suresh , Enkelmann Volker , Moeßner George , Müllen Klaus
Published: March 2011

Simple molecular building blocks for creating supramolecular architectures in the crystal lattice are described. Combination of hydrogen bonding and alkyl chain crystallization is used to explore self‐assembly1 of molecular building blocks 1, 2, 3 and 4 in the crystal lattice. The crystal lattice of pure acids and its equimolar mixtures with bifunctional hydrogen bond acceptors are characterized by singe crystal analysis.
Investigation of α‐keratin intermediate filament structure by molecular dynamic simulation
Authors: Knopp Birgitta , Jung Bemd , Wortmann Franz‐Josef
Published: March 2011

Molecular dynamic simulations are carried out in order to investigate the stability of the secondary and tertiary structure of the intermediate filaments monomer unit of wool. Based on the assumed secondary structure three segments of the primary structure are selected: 1A, L1,2 and a part of 2B. With the ideal α‐helix as start conformation, the simulations are carried out with the MD‐algorithm of DISCOVER 2.9.0 (BIOSYM, 1993) and the CFF91 force field for 500 ps at different temperatures in vacuum. In either simulation a destabilization of the helical structure with an increase of the simulation temperature is observed. By monitoring the length distribution of the axially oriented (O···H)‐hydrogen bonds, which stabilize the helical structure, transition temperatures for the α‐helical denaturation are determined. The supposedly α‐helical segments 1A and 2B show significantly higher transition temperatures than segment L1,2. This lower temperature confirms the expectation from the amino acid sequence that the linker segment shows more conformational flexibility and is nonhelical at room temperature.
Prospects and challenges of reactive processing
Authors: Joachim Rösch , Holger Warth , Philipp Müller , Rüdiger Schäfer , Christof Wörner , Christian Friedrich , Jörg Kressler , Rolf Mülhaupt
Published: March 2011

Chemical reactions during polymer melt processing afford a wide range of highly diversified polymers derived from well‐known polymers. This technology, especially functionalization, grafting, in‐situ formation of copolymers, segmented polymers, and compatibilizers, plays a key role in the development of novel thermoplastics including blends, composites, and polymers from renewable resources. Oxazolines are useful highly reactive and selective intermediates for polymer melt modification.
The processing and properties of conductive polypropylene/polypyrrole composites
Authors: Omastová Mária , Piontek Jürgen , Janke Andreas , Košina Stanislav
Published: March 2011

Polypropylene (PP) particles were chemically coated with polypyrrole (PPy). The content of polypyrrole varied from 0.8 to 7.6 wt.‐%. Electrical conductivity of compression moulded samples depends on the concentration of polypyrrole and reached values from 4×10−10 to 5×10−3 S/cm, which is about 7 orders of magnitude higher than the conductivity in the blends prepared by mechanical mixing of PP and PPy in the same PPy concentration range. Highly conductive composites were also obtained from a mixture of coated and non‐coated PP particles.

The PP/PPy composites were characterized by elemental analysis, SEM and mechanical testing. The antistatic properties of PP/PPy composites were demonstrated. The electrical and mechanical properties depend on processing of composites.
Homogeneous mixtures of polybetaines with low molecular weight salts
Authors: Bonte Nelly , Laschewsky André , Mayer# Bernd , Vermylen Valérie
Published: March 2011

The prepaparation of amorphous, homogeneous blends of zwitterionic polymers with various low molecular weight salts, and in particular with ionic dyes was studied. Homogeneous miscibility was achieved in many cases up to equimolar amounts of salt, even for bulky compounds. Whether miscibility is achieved, or not, depends in a subtle way on the chemical structure of the salt, but no obvious correlation between structure and miscibility could yet be revealed. Spectral shifts of the dye UV/Vis spectra in solution as well as in bulk suggest strong interactions between the polybetaines and the admixed salts.
On the interaction of the morphological structure and the LC behaviour of LC side group block copolymers
Authors: Fischer Hartmut , Arnold Manfred
Published: March 2011

The interaction between morphological structure and phase behaviour of a group of LC side group block copolymers have been investigated using DSC, TEM and small angle X‐ray diffraction. Generally, phase separation between the two blocks was observed. It was found that in the case of those samples, where the liquid crystalline sub‐phase is not continuous (spheres), only a nematic phase is seen, whereas in all samples in which there is a continuous liquid crystalline sub‐phase, the smectic A phase of the homopolymer is formed. On the other hand, the block copolymer seems to stabilise the LC‐phase and the polymer properties in general, no dependency of the clearing temperatures and of the glass transition temperatures from the molecular weight of the LC blocks has been detected.
Supramolecular polymer interactions using melamine
Authors: Lange Ronald F. M. , Meijer E. W.
Published: March 2011

Triple‐hydrogen bonding between the imide containing polymers 1a‐c and melamine 2 is used to obtain supramolecular interactions between macromolecules. Melamine, known as a compound barely soluble in any organic solvent, is molecularly dissolved in the copolymers 1a‐c by meltprocessing. Maximum concentrations of 1 equivalent amount of melamine per 2.5 equivalent amounts of copolymer are obtained, indicating a 3:1 mol:mol superstructure with physical crosslinking by hydrogen bonding. Crystalline melamine is detected by powder diffraction X‐ray analysis at melamine concentrations exceeding the 3:1 imide‐melamine mole ratio.
Structure of crystals of nylon 6,3 and related polymers: Folding is stabilized by thermodynamic interactions
Authors: Subirana Juan A. , Aceituno Juana E.
Published: March 2011

The n,3 polyamides have the structure: [‐(CH2)n NHCOCH2CONH‐]×. Due to the stereochemistry of the malonamide unit, these polymers have a unique hydrogen bonding system with two different orientations at 120°: they do not form hydrogen bonded sheets as in conventional polyamides. We have obtained a very well oriented mat from crystals of this polymer which shows up to ten orders of the lamellar spacing. In this paper we analyze the structure of the fold in the crystal surface of nylon 6,3 and in related polyamides, including polyglycine. The thickness of these lamellar crystals is in agreement with the values determined for other polyamides. These results, taken together with some recent findings with other polymers, indicate that the thickness of polymer lamellar crystals may be thermodynamically controlled. An outline of this hypothesis is presented.
Role of the cure kinetics in morphology control at phase separation of curing multicomponent thermosets and a criterion of equilibrium
Authors: Rozenberg Boris A. , Sigalov Grigory M.
Published: March 2011

The formation of heterophase polymers via phase separation in the course of curing reaction in a blend of a thermosetting oligomer with a rubber modifier is considered. The interference of thermodynamic and kinetic factors that define the morphology of the material being formed is discussed. The need for a kinetic theory of cure‐induced phase separation is established, and an approach of this kind is proposed. On the basis of this approach a simple quantitative criterion of deflection of the phase‐separating system from the thermodynamic equilibrium is given.
Polymer bound chromogenic crown‐ethers as the cladding material for polymer optical waveguides
Authors: Klok Harm‐Anton , Möller Martin
Published: March 2011

The synthesis and spectroscopic characterization of the chromoionophoric poly(methyl methacrylate‐co‐N‐(9‐[10‐methacryloylmethyl]anthrylmethyl)monoaza‐18‐crown‐6) (4) copolymer is described. Complexation of K⊕ by extraction from aqueous medium with toluene solutions of (4) was found to enhance the intensity of fluorescence up to 40% compared to the situation in which no K⊕ was complexed. For low concentrations, the intensity of fluorescence was found to increase linearly with the concentration of K⊕ in the aqueous solution. The copolymer (4) might be used for the transduction of the chemical recognition of K⊕ into an optical signal in evanescent wave fluorescence chemical sensors based on poly(methyl methacrylate) optical waveguides.
Polymer light emitting diodes
Authors: Greczmiel Michael , Pösch Peter , Schmidt Hans‐Werner , Strohriegl Peter , Buchwald Elke , Meier Martin , Rieß Walter , Schwoerer Markus
Published: March 2011

Monolayer light emitting diodes from poly(1,4‐phenylenevinylene) (PPV) usually exhibit relatively low quantum efficiencies. So the external efficiency of an ITO/PPV/Ca LED is typically 0.01%. In order to increase the quantum yield in bilayer devices, oxadiazole polymers have been used. The syntheses of a number of novel polymethacrylates with pendant oxadiazole groups and some aromatic polyethers with oxadiazole units in the main chain are described. These polymers with the electron withdrawing oxadiazole units facilitate electron injection and transport in bilayer LEDs with PPV as hole transport layer. Thus an LED with a top layer of the polyether 3a exhibits a tenfold increase of the external quantum efficiency to 0.1%. Compared to conventional PPV LEDs, the improved bilayer devices show intense emission at low current densities.
Gel template leaching: An approach to functional nanoporous membranes
Authors: Gankema Harold , Hempenius Mark A. , Möller Martin , Johansson Gary , Percec Virgil
Published: March 2011

A novel preparation method for nanoporous structures, denoted “Gel Template Leaching”, is described. The approach is based on the gelation of solutions containing two low molecular weight compounds of which one is crystallizable and the other curable. Gelation of the solute upon cooling followed by curing of the solvent below the gelation temperature lead to the formation of a semi‐IPN consisting of a reversibly and a covalently crosslinked network. After leaching of the solute (the template) a well‐defined nanoporous architecture was formed. Functional pores could be obtained after charging the pore walls with ionic sites.
Organic thin film pyrosensors
Authors: Brehmer Ludwig , Kaminorz Yvette , Grasnick Gerd , Herkner Georg
Published: March 2011

Recent developments in sensor technology show the suitability of thin pyroelectric films for the construction of pyroelectric sensor devices made from polymer materials. These materials are used for its advantageous thermal properties and also for its suitable frequency behaviour. Pyroelectrical measurements have been provided on thin films based upon poly(vinyl alcohol)s and poly(siloxane)s with azobenzene side chains. Relaxation behaviour and stability of poled pyroelectric polymers are discussed and related to the results of dipole relaxation measurements provided at our laboratories.
Preparation and properties of self‐reinforced polypropylene/liquid crystalline polymer composites
Authors: Postema Adri R. , Fennis Paul J.
Published: March 2011

A fast and potentially economic method for creating a composite material of polypropylene (PP) with liquid crystalline polymers (LCPs) was explored. The LCPs were dispersed in the PP matrix in a conventional extrusion process and subsequently drawn in order to obtain a highly uniaxially molecular orientation of the LCP fibres. The strongest mechanical properties were found after rapid cooling of the blend, which was optimally exploited in thin filaments where cooling was fast enough to prevent fibre break‐up and/or orientation relaxation.

To enable the production of extrudates which are thick enough to be cut into self‐reinforced pellets, a fused multi‐filament technology was developed. In this technology several thin filaments were extruded/drawn and rapidly cooled to a temperature between the crystallisation temperatures of the LCP and the PP. After solidification of the LCP, the single filaments were fused to a multifilament strand and further cooled to room temperature. The thick multifilament LCP reinforced PP strands were cut into pellets and used in injection‐and compression‐moulding processes. This processing took place between the melting temperature of the PP and the LCP, with retention of the aspect ratio and the molecular orientation of the LCP fibres.
Strategies for the development of haemocompatible dialysis membranes
Authors: Diamantoglou M. , Vienken J.
Published: March 2011

Haemocompatibility is the number one target of membrane development for haemodialysis, because chronic renal failure and the subsequent dialysis‐treatment is affecting more and more patients. Two strategies are currently in use to achieve the goal of new blood compatible polymers: Firstly, existing cellulosic membranes are modified by introducing functional groups through ether and ester bonds and secondly, synthetic polymers are mixed with bulk additives or copolymerized with other polymers. Biological responses as a consequence of blood/material interaction are common observations. However, blood compatibility in general cannot be improved by a single membrane surface feature. The assessment of a series of surface properties shows that physiological defense systems, like complement and cell activation, or coagulation are differently stimulated by means of the same surface structures of biomaterials. Thus, a compromise has to be found, already during membrane development.

We synthetized a series of modifications of cellulosic membranes with the aim to investigate whether the type of substituent and its degree of substitution has an influence on the blood compatibility of these dialysis membranes. Data indicate that alterations in the lipophilic/ hydrophilic balance (HLB) on the polymer surface may explain substituent‐related changes in haemocompatibility. Optimal degrees of substitution are characteristic for a given type of substituent and enables the membrane manufacturer to tailor materials for improved blood compatibility.
Surface characterization of hemodialysis membranes based on electrokinetic measurements
Authors: Werner Carsten , Jacobasch Hans‐Jörg
Published: March 2011

Hemodialysis 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

Three 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

Comparative 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

The 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

Scientific, 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

Nucleation 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

Surface 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

Elastomer 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

The 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

A 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

There 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

Hyaluronic 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.
Macromolecular ligands for homogeneous catalysts
Authors: Bergbreiter David E.
Published: March 2011

Strategies to use macromolecular‐metal complexes in homogeneous catalysis are discussed and summarized. General advantages, problems and future opportunities in this broad research area are discussed.
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

Amphiphilic 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

Stable 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

Multielectron 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

The 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

The 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

Manganese 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

Hydroformylation 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

X‐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

A 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

Methodology 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

An 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

The 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

The 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

It 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

Two 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.
Equilibrium nano‐structures in poor solvent polymer solutions near glass transition temperature
Authors: Dormidontova Elena , Erukhimovich Igor , Khokhlov Alexei R.
Published: March 2011

Poor solvent polymer solutions near the glass transition temperature are considered on the basis of the nonlocal entropy model which allows the possibility of microphase separation transition. The dependence of the magnitude of nonlocal entropy and nonlocality radius on the temperature are explicitly taken into account. It is shown that accounting for nonlocal entropy can lead to i) the solubility enhancement in the vicinity of glass transition temperature, ii) microphase separation transition. Microphase separation transition is studied in the weak segregation limit. Phase diagrams containing the regions of stability of different microdomain structures, as well as the regions of macroscopic phase separation, are obtained.
Interface effects in nematic liquid‐crystalline structures of polymer solutions
Authors: Kuznetsov Dmitri V.
Published: March 2011

A solution of long semirigid linear macromolecules was considered. The liquid‐crystalline nematic ordering in the solution was analyzed theoretically using an Onsager‐type approach. The orientation entropy was calculated in the frameworks of Lifshits' approach, successfully developed for this system originally by Khokhlov and Semenov. For homogeneous liquid‐crystalline phase using the third virial approximation for intersegmental steric interaction the orientation distribution function, the free energy density, the isotropic‐nematic coexistence and the spinodal conditions were computed numerically for two types of polymer flexibility mechanism: persistent chains and chains of freely joint segments. For the asymptotically exact second virial approximation the applicability region was analyzed. We considered the general equations, which describe the concentration and orientational segment distribution for a semirigid persistent polymer chain at a surface (or interface) of any shape and orientation. These equations were numerically solved for the case when the nematic director axis was perpendicular to a planar interface boundary between the real coexisting nematic and isotropic phases. The coordinate‐dependencies of the polymer concentration and of the order‐parameter take the smooth two‐steps form in the interface region.
Interfacial tension of a demixed A/B polymer blend with A‐B diblock copolymer near the critical point
Authors: Nose Takuhei
Published: March 2011

Effects of A‐B diblock copolymers on the interfacial tension of a demixed homopolymer A/B blend near the critical point has been studied theoretically and experimentally. A simple theory developed here predicts that a crossover from weak to strong reduction of interfacial tension with addition of a small amount of diblock copolymers can be observed upon going away from the critical temperature, where the interfacial tension exhibits a maximum in its temperature dependence, if polymeric index of the diblock copolymer is much larger than that of the homopolymers. The temperature of the maximum approaches the critical point with increasing copolymer concentration. These predictions have experimentally been confirmed for a demixed oligo(styrene)/oligo(dimethylsiloxane) blend with poly(styrene)‐block‐poly(dimethylsiloxane).
Effect of molecular architecture on DBS‐induced block copolymer gels: A rheological study
Authors: Nuñez Carlos M. , Whitfield J. Kaye , Mercurio Debra J. , Ilzhoefer John R. , Spontak Richard J. , Khan Saad A.
Published: March 2011

Dibenzylidene sorbitol (DBS) is capable of gelling a variety of organic solvents and polymeric materials by forming a rigid, 3‐D hydrogen‐bonded network. In this work, two poly(siloxane)/poly(propylene oxide) segmented copolymers of equal composition and molecular weight, but different architectures (endblocked vs. pendant), as well as a pure poly(propylene oxide), have been gelled with DBS. We have investigated the dynamic rheological properties of these gels to ascertain the effect of copolymer architecture, PDMS comonomer and DBS concentration on network formation.
Comparison of the association process in physical gels and in polymers with small amounts of stickers
Authors: Rogovina L. Z. , Vasil'Ev V. G.
Published: March 2011

The association processes in physical gels and physical networks with smal amount of stickers are compared on the basis of the generalization of literature data and our own results on the gels of gelatine, PVA and olygocarbodiimides as well as on the physical network formation in poly(dimethylcarbosiloxane) with side COOH groups. The measurement of the rheological properties is used as a main method of the association evaluation. The role of the rearrangement of the intra‐ to intermolecular bonds and of the thermodynamic quality of the solvent in the process of physical network formation is emphasized.
Nanosize metal clusters in polymer systems
Authors: Sergeev Gleb B. , Gromchenko Irina A. , Petrukhina Marina A. , Prusov Andrey N. , Sergeev Boris M. , Zagorsky Vyacheslav V.
Published: March 2011

Three synthetic methods have been developed for embedding nanosize metal clusters into polymers: (i) in situ synthesis of silver nanoparticles in cross‐linked poly‐acrylamide gels, (ii) implantation of cryochemically produced silver nanoparticles into poly‐acrylamide gels, and (iii) encapsulation of metal nanoparticles in poly‐p‐xylylene films. All methods allow one to produce 3–20 nm stable metal clusters embedded into bulk materials, thin films or fine particles dispersed in organic solvents or water. Results on some physical properties of the metal‐polymer systems thus obtained are presented.
Microscopic inhomogeneities in weakly‐charged temperature sensitive polymer gels and solutions
Authors: Shibayama Mitsuhiro
Published: March 2011

A comparison of small‐angle neutron scattering (SANS) intensity functions, I(q), was made between gels and solutions of poly(N‐isopropyl acrylamide‐co‐acrylic acid) (NIPA/AAc), where q is the magnitude of the scattering vector. I(q)'s were strongly dependent on polymer concentration as well as temperature. At low temperatures, I(q)'s for both gels and solutions were similar to each other and were monotonous decreasing functions. However, at high temperatures above θ, the so‐called theta temperature of poly‐NIPA in aqueous solution, both had a distinct peak and a significant difference appeared in I(q) due to the presence or absence of crosslinks. Origins of the peak and the differences in I(q) are discussed.
Molecular dynamics simulation study of the dynamics of fluids at solid‐liquid interfaces
Authors: Winkler Roland G. , Schmid Rolf H. , Reineker Peter
Published: March 2011

The dynamics of fluids at solid‐liquid interfaces is investigated. In particular, we consider a simple Lennard‐Jones fluid as well as a melt of hexadecane chains. For the Lennard‐Jones fluid, the numerical results are compared with analytical calculations based on the diffusion equation, which shows that the numerical results can very well by described by the solution of the diffusion equation for reflecting surfaces. The diffusion coefficient is practically independent of the position within the film, although the fluid is inhomogeneous perpendicular to the surface. In contrast, the dynamics of the centers of mass of hexadecane molecules perpendicular to repulsive surfaces is severely slowed down due to their extended and anisotropic nature and cannot be described by a single particle diffusion equation.
Kinetics of collapse and decollapse of a single double‐stranded DNA chain
Authors: Yoshikawa K.
Published: March 2011

Transition of a single duplex DNA between elongated coil and condensed globule has been studied by the technique of single molecular observation with fluorescence microscopy. It has become clear that individual DNA chains undergo first‐order phase transition. We have observed the time‐dependent change of the DNA structure accompanied with the phase transition from coil to globule. The speed of the compaction was found to be almost constant along the DNA chain. It is indicated that the coil‐globule transition exhibits the phenomenon of “nucleation and growth”. The process of the decollapse of a single DNA has also been observed, the time dependence of the long axis length being described as l ∼ t1.8.