bluuebunny/crossref_metadata_2025 huggingface dataset:
Liposome delivered and polymeric metal complexes as potential sensitizers for the photodynamic therapy of cancer
Authors: Wöhrle Dieter , Shopova Maria , Moser Jörg G. , Kliesch Holger , Michelsen Ulrike , Müller Silke , Weitemeyer Andrea
Published: March 2011

Different possibilities of macromolecular metal complexes as photosensitizers (PS) for their potential use in the photodynamic therapy of cancer are described. The prepared metal porphyrazin derivatives (metals: Zn(II), Si(IV)(X)2) exhibit long wavelength absorption and high singlet oxygen quantum yields under irradiation. One possibility is the incorporation of the PSs in liposomal vesicles giving hydrophobic conjugates with low densitiy proteins in the serum after injection. Good tumor accumulation and photodynamic activities are observed. Increased tumor uptake is also known for Pcs covalently connected via the ligand to poly(ethylene glycol monomethyl ether). New compounds contain the hydrophilic polymer at axial substituents of Si(X)2Pc and Si(X)2Nc. Some newly synthesized compounds with only one functional group exhibit the possibility of coupling to macromolecules like e.g. monoclonal antibodies.
The first bisgermylene, its synthesis and addition to organic halides and dihalides
Authors: Cao Shaokui , Kobayashi Shiro
Published: March 2011

The first bisgermylene with an acyclic structure was synthesized for the first time by one‐pot, two‐step ligand substitution reactions from the 1,4‐dioxane complex of germanium dichloride. The reactions of the bisgermylene with organic halides gave corresponding oxidative addition products, and with organic dihalides gave oligomeric polyadditon products.
Molecular orientation of paramagnetic metal complex by melt‐drawing thermotropic liquid crystalline polymers
Authors: Hanabusa Kenji , Koyama Toshiki , Shirai Hirofusa
Published: March 2011

New liquid‐crystalline polyesters and paramagnetic vanadyl complex were prepared as host polymer and guest complex. Melt‐drawn fibers were made from the blend of host polymer and guest complex at the mesophase temperature. ESR spectra of the melt‐drawn fibers indicated that the base of pyramidal vanadyl complex is completely oriented parallel to the fiber axis.
Building up a conjugated system by the palladium‐catalyzed arylation of ethylene (heck reaction)
Authors: Kiji Jitsuo
Published: March 2011

The palladium‐catalyzed arylation of ethylene under aqueous conditions has been studied. Both NaHCO3‐soluble and ‐insoluble bromo‐and iodoarenes possessing electron‐withdrawing groups react with ethylene to afford styrenes in good yields by water‐soluble PdCl2[tppms]2 (tppms, m‐(diphenylphosphino)benzenesulfonate). The Cr(CO)3 complex of chlorobenzene reacts similarly under organic conditions. These reactions provide a synthetic route to poly(phenylenevinylenes).
Studies on the ultra‐fine transition metal particles dispersed in polymer matrix
Authors: Chen Lei , Yang Wenjun , Yang Changzheng
Published: March 2011

A series of complexes of styrene‐4‐vinylpyridine copolymers (SVP) or poly(4‐vinylpyridine) (PVP) and transition metal chlorides were prepared. The transition metal‐polymer complexes were used to prepare the ultra‐fine metallic particles dispersed in polymer matrix by chemical reduction. The effects of the ion concentration and the polymer backbone on the size of these metal particles were studied. It was found that the transition metal ions may coordinate to pyridine groups in precursor polymers after blending. Upon reduction, the metal ions were transformed into the corresponding metal particles in the range of nanometer scale. The protective polymers take an important role to prevent metal particles from oxidation and excessive aggregation.
Liquid crystalline polymers at interfaces
Authors: Halperin Avi , Williams David R.M.
Published: March 2011

Main chain liquid crystalline polymers (LCPs) at solid‐nematic interfaces exhibit a variety of phase transition between distorted and undistorted states. In one case the transition results from the confinement of grafted chains immersed in a nematic solvent and subject to homeotropic anchoring. The general features of the transition are similar for long and for short chains. The detailed physics is different since long chains exhibit Gaussian, entropic elasticity while the elasticity of the short chain is due to their rigidity. As a result it is possible to weakly confine long chains without triggering a distortion while for short chains the nematic distortion occurs simultaneously with the buckling of the rod like LCPs. Related effects are found for uniformly adsorbed LCPs and for free, confined chains. Different scenarios are expected when homogeneous anchoring is imposed.
Synthesis and investigation of new water soluble sulfonated rigid‐rod polynaphthoyleneimide
Authors: Timofeeva Galina I. , Ponomarev Igor I. , Khokhlov Alexei R. , Mercier R. , Sillion B.
Published: March 2011

A new water‐soluble rigid‐rod sulfonated polynaphthoyleneimide (PNIS) was synthesized. The structure of PNIS has been confirmed by elemental analysis, NMR (1H, 13C), full X‐ray investigation of model compound. Viscosity measurements, sedimentation and light‐scattering experiments of PNIS solutions confirm the suggested aggregation of this polymer and an increase of its molecular weight without being substantially changed in different types of aqueous solution. These aggregates could consist of very tightly packed rigid rods.
Shape persistent macromolecules as building units of complex supramolecular architectures
Authors: Wegner Gerhard
Published: March 2011

Chain‐rigidity is defined as a structural principle leading to self organization depending on the aspect ratio of the molecular objects and their mutual interactions. These molecular objects serve as the building blocks of systems for which ultrathin layers composed of hairy rod macromolecules (HRM) are an example. Depending on architectural details layered architectures of HRM are models for molecular nanocomposites, exhibit interesting optical, electrochemical, dielectric or barrier properties. They are also designed to be used in devices the performance of which depends on molecular interactions. A systems approach is emphasized as part of the synthetic strategy.
Effect of initiators, lewis acids, deactivators, additives and medium on controlled/“living” carbocationic systems
Authors: Matyjaszewski Krzysztof
Published: March 2011

Effect of nucleofugacity of leaving group, X, nucleophilicity/basicity of the formed counteranion, X− or MtXn+1−, and groups stabilizing positive charge in the carbocation, R+, generated from initiator, RX, as well as metal and ligands in the Lewis acids, MtXn, strength of protonic acids, HA, added salts, NR4+X−, nucleophiles, Nu, some other additives and also reaction conditions on controlled/“living” carbocationic polymerization is discussed. The role of all of the components is explained and their rational design for various monomers which can be polymerized cationically to well defined polymers and copolymers is provided.
Anionic synthesis of well‐defined polymer blends by controlled chain‐transfer reactions
Authors: Quirk Roderic P. , Li Jinsong
Published: March 2011

The scope and limitations of controlled chain transfer reactions in living anionic polymerization have been investigated. In contrast to the random nature of normal chain transfer reactions, this procedure first effects controlled living anionic polymerization followed by addition of a stoichiometric amount of suitable chain transfer agent when the monomer has been completely consumed. The resulting anionic species is then used to initiated polymerization of a second monomer charge with the same monomer or with a different monomer. A variety of hydrocarbon acids and amine compounds with pKa values in the range of 30–40 have been evaluated as chain transfer agents in the presence and absence of coordinating ligands. Efficient chain transfer to poly(styryl)lithium has been observed using 1,1‐diphenylpropane. Reinitiation efficiency to both styrene and butadiene monomer was quantitative and controlled blends of different molecular weight polystyrenes or blends of polystyrene with polybutadiene have been prepared. The use of these chain transfer reactions to prepare functionalized polymers has also been investigated.
Polyisobutylene based designed polymers
Authors: Mishra Munmaya K.
Published: March 2011

The field of cationic polymerization has moved center stage with the recent discovery of living polymerization that lead to the design of polymers with controlled molecular architecture. This report will provide a brief introduction of living cationic polymerization of isobutylene (IB) by tertiary ethers, and new cationic initiating systems based on peroxides and hydroperoxides. This paper will also briefly review some our recent work on the design of block copolymers via multi‐mode polymerization (cationic–radical transformation) including the synthesis of star‐blocks. The application of polyisobutylenes (PIBs) in the design of “beaded molecular strings,” a new class of molecular assembly will be discussed as well.
Investigation of the Mechanism of Crossover Reaction of p‐Dicumyl chloride/BCl3/Isobutylene System by Glass Fiber Optic Photometry
Authors: Kéki S. , Bogács L. , Cs Bogács , Zsuga M.
Published: March 2011

A thorough kinetic investigation was done by measuring the optical density of reaction mixtures of the pDCC/BCl3 initiating system in the presence and in the absence of monomer and added salt at 500 nm and at −80°C. The absolute rate constants of elementary steps of the ion generation and cationation were evaluated by computer using a fitting method for determination of the parameters occurring in the kinetic model. The key activated species of the mechanism are identified to be colorless donor‐acceptor complexes. The color of reaction mixtures is caused by ionized species. On the basis of the calculations and other evidences, a well‐established mechanism is proposed. Both ‐tC‐Cl and ‐tC‐OH endgroups were found by MS/EI. GPC analysis of the reaction products indicates that the major product is dimer under the reaction conditions applied.
Tetraalkylammonium salts as additives in anionic polymerization of methyl methacrylate
Authors: Tsvetanov Christo B. , Novakov Christo P.
Published: March 2011

The anionic polymerization of methyl methacrylate was carried out in the presence of t‐BuOK/Quaternary ammonium salt (QAS) and α‐lithio‐ethylisobutyrate/QAS in toluene and THF. Seven QAS and one quaternary phosphonium salt of different size and shape were used as modifiers. With the aid of the model system alkali picrate/QAS, it was found that the interaction between the picrate salt and QAS in toluene does not proceed as a pure cation exchange reaction. Two types of adducts were distinguished: Initiator/QAS with a very long hydrocarbon chain (>C12) promote isotactic placement, while the adducts t‐BuOK/QAS with two or more bulky substituents produce a highly syndiotactic polymer with high conversion and comparatively low polydispersity in pure toluene.
Application of magnetic resonance spectroscopies to the characterisation of elastomer/filler systems
Authors: Legrand André Pierre
Published: March 2011

Contribution of the magnetic resonance spectroscopies to the determination not only of the chemical structure but also of the dynamics of the polymer chains is examined. Analysis of such complex systems involves different aspects. Questions as: the nature of the crosslinking via sulfur bridges, presence of additives, influence of the heat treatments, behaviour under strain, analysis of the interphase … are considered. A part is devoted to the dynamic behaviour of the chains in the interphase elastomer/filler.
Surface microstructure of carbon black: Advances in characterization by scanning tunneling microscopy
Authors: Donnet Jean‐Baptiste , Wang Tong Kuan
Published: March 2011

The recent advances in the characterization of the surface structure of carbon black by scanning tunneling microscopy (STM) are reported. The atomic organization, at the surfaces of several carbon blacks, is well resolved by STM and a local paracrystalline structure model is proposed, where the distorted carbon layer and thus the unequal inter‐layer distance are evidenced on the basis of the classical turbostratic stacking. The quantitative analysis of the STM image, which enables a quantitative assessment of the surface crystallinity and of the nanoscale roughness, is presented.
Rheological properties of filled polymers
Authors: Carreau Pierre J. , Lavoie Paul‐André , Bagassi M'Hammed
Published: March 2011

The rheological properties of two model suspensions using a Newtonian polymeric matrix are presented and discussed in light of results presented in the literature. It is shown that particle‐particle interactions in concentrated suspensions are responsible for a gel‐type behavior at very small strain and strain hardening at a critical strain. Suspensions of concentrated colloidal particles in a Newtonian matrix behave like typical viscoelastic molten polymers, but the properties are strongly dependent on the solids dispersion, and strain at small strain. A simple rheological model is proposed to describe the shear viscosity of these suspensions.
Physical properties of sol‐gel derived poly(Vinylidene Fluoride)/Silica hybrid
Authors: Yano Shoichiro , Okubo Nobuaki , Takahashi Kazutaka
Published: March 2011

Poly(vinylidene fluoride) (PVDF) was incorporated in situ with silica by a sol‐gel process involving tetraethoxysilane. The mechanical properties of these in situ hybrids were compared with those of PVDF composites mechanically blended with 14‐nm diameter fumed silica particles. The ultimate strength of the in situ hybrids was higher than that of the blend composites, since fumed silica particles aggregate and act as mechanically weak points. The thermal analysis, dynamic viscoelastic properties, and dielectric properties were compared. The β‐relaxation of PVDF caused by the glass transition was observed at around −40°C in the differential scanning calorimetry (DSC) and the mechanical tan δ curves and at −30°C in the dielectric loss factor (ϵ”) curve. The αc‐relaxation due to the molecular motion in the crystalline phase occurred at 61°C in DSC curve, at 100°C in the tan δ curve, and at 80°C in the ϵ” curve. The peak positions of these relaxations did not change, but the peak intensities were decreased with the increase in silica content for both the in situ hybrids and blend composites. The activation energies for PVDF were calculated as 136 kJ/mol for the β‐relaxation and 96 kJ/mol for the αc‐relaxation. The result that these activation energies did not depend on silica content may indicate the weak interaction between PVDF and silica.
Subcutaneous hydrogel reservoir system for controlled drug delivery
Authors: Kuzma Petr , Moo‐Young Alfred J. , Mora Daniel , Quandt Harryp , Bardin Clyde W. , Schlegel Peter H.
Published: March 2011

Hydro Med Sciences has developed a subcutaneous reservoir hydrogel implant capable of long term delivery of predetermined doses of various active compounds. The implant is a small‐diameter, thin‐walled cylindrical capsule containing a therapeutic agent. The hydrogels used for this application were Hydron* type copolymers of 2‐hydroxyethyl methacrylate (HEMA). These non‐erodible hydrogels are known to be biocompatible, swell reversibly in an aqueous environment, resist biodegradation and do not support microbial growth.
A hydrogel with rubber elasticity transition
Authors: Nagasaki Yukio , Kazama Kenji , Honzawa Eiichi , Kato Masao , Kataoka Kazunori , Tsuruta Teiji
Published: March 2011

Reaction between dimethyldivinylsilane and 3,6‐diazaoctane in the presence of 3‐lithio‐3,6‐diazaoctane yields a new telechelic oligomer, poly(silamine), which consists of alternating 3,3‐dimethyl‐3‐silapentane and N,N′‐diethylethylenediamine units in the main chain. Poly(silamine) shows unique phase transition properties in response to the degree of protonation of amino groups in the polymer. Poly(silamine) also shows a strong interaction with several anions. Due to the interaction between poly(silamine) and anions along with the protonation of amino groups in the poly(silamine), the rubber elasticity of poly(silamine) is drastically changed. A discrete volume change can be observed when the environmental pH of the poly(silamine) gels is varied. This can be explained not only by a change in ionic osmotic pressure but also by a change in the rubber elasticity of the networks in the gel.
Noninvasive optical characterization of hydrogels
Authors: Weiss Aryeh M. , Khayutin Leonid , Bentolila Alfonso , Domb Abraham
Published: March 2011

This paper presents results based on concentration quenching of fluorescence polarization (cqfp), which demonstrate the feasibility of using cqfp to measure changes in hydrogel‐membrane hydration. This is accomplished by binding fluorescent molecules to the hydrogel matrix, and showing that the fluorescence polarization is a monotonic function of fluorophore concentration. Films based on crosslinked 2‐hydroxyethyl methacrylate containing lissamine side groups (10−4‐10−7 mol/l) were mounted in a special cell which provided an aqueous environment, and in which polarized fluorescence could be measured. An argon‐ion laser provided polarized excitation at 488nm, and the polarized fluorescent emission was detected. The correlation between the fluorescence polarization and the bound dye concentration was found to correspond to the theoretically expected behavior.
Mechanical and wear properties of poly(vinyl alcohol) hydrogels
Authors: Cha Won‐Ill , Hyon Suong‐Hyu , Oka Masanori , Ikada Yoshito
Published: March 2011

Poly(vinyl alcohol)(PVA) hydrogels with low water contents were prepared by low temperature crystallization of PVA solution from a dimethyl sulfoxide/H2O mixed solvent, followed by high‐temperature annealing after drying and the subsequent re‐swelling with water. The tensile strength and dynamic modulus of PVA hydrogels increased upon annealing, irrespective of the degree of polymerization (DP) of PVA, but always at the sacrifice of the water content of hydrogel. In addition to the mechanical strength, the hardness of PVA hydrogels was improved by lowering the water content. The highest tensile strength(20 MPa) and the highest dynamic modulus(180 MPa) were obtained when hydrogel was prepared from PVA with DP of 11 000 and annealed at 140°C for 24 h. The wear resistance strongly depended on the mechanical strength and coefficient of friction of PVA hydrogels. The wear volume of the hydrogel prepared from PVA with DP of 8 800 decreased with the decreasing coefficient of friction and the increasing mechanical strength of PVA hydrogel except for the 25 wt% PVA hydrogel at 2.5 MPa. Furthermore, any wear particles were not detected for the 45 wt% PVA hydrogel at 2.5 MPa and the 25 wt% PVA hydrogel at 2.0 and 2.5 MPa.
Synthesis and characterization of highly wettable hydrogel coatings for immobilization of marine bacteria
Authors: Gatenholm P. , Michálek J. , Vacík J.
Published: March 2011

This study evaluates hydrogels based on 2‐hydroxyethyl methacrylate (HEMA) and diethylene glycol ester of methacrylic acid (DEGMA) as candidates for a suitable matrix for immobilizing marine bacteria. Results are presented of investigations of the effect of monomer structure and polymer composition on wettability and mechanical properties. We also studied the effect of composition on heat produced during polymerization, an important factor affecting bacterial viability during the process of immobilization. Hydrogels based on DEGMA in artificial sea water solution demonstrate the attractive combination of good mechanical properties and high water content. At low concentrations of monomer, little heat is produced during polymerization. These properties make DEGMA‐based hydrogels suitable for immobilizing marine bacteria.
Experiences with interlaboratory GPC experiments
Authors: Bruessau Rudolf J.
Published: March 2011

Based on some round robin experiments organized in the last years by a DIN working group and by the IUPAC working party IV.2.2, the paper discusses measures for getting a better interlaboratory reproducibility of GPC results. The most important points are:

‐ selecting columns according to their separation selectivity and range

‐ avoiding artifacts in the distribution curves, caused by gaps in the pore volume distribution

‐ avoiding adsorption and memory effects

‐ calibration: using calibration standards of high quality selecting suitable calibration points checking the influence of the injected concentration

‐ selecting a common detector

‐ data treatment, especially finding the correct baseline

‐ preparing a detailed data report according to a uniform schedule.
Effects of electrostatic and hydrophobic interactions on the chromatographic behavior of biopolymers in HPLC columns
Authors: Corradini Danilo
Published: March 2011

The effect of electrostatic and hydrophobic interactions on the chromatographic behavior of biopolymers with the use of chemically bonded silica‐based HPLC columns and aqueous buffered mobile phases containing neutral salts in a wide range of concentration is discussed. Two columns packed with stationary phases appositely designed for biopolymer HPLC in size exclusion and anion exchange mode, respectively, are examined. Experimental data are evaluated by plotting the measured isocratic elution volumes of several standard proteins of different isoelectric point against the salt concentration in the mobile phase. Depending on the concentration and nature of salt, both columns exhibit different domains where either sieving effect or electrostatic or hydrophobic interactions are predominant. At sufficiently low salt concentrations electrostatic interactions are predominant leading to either increasing or decreasing elution volumes depending on the sign of the charges on the stationary phase and the protein, respectively. On the other hand, at high salt concentrations of a salt with sufficiently high molal surface tension increment proteins may be retained by hydrophobic interactions.
Catalytic chain transfer polymerisation (cctp) of methyl methacrylate: Effect of catalyst structure and reaction conditions on chain transfer coefficient
Authors: Haddleton David M. , Maloney Darren R. , Suddaby Kevin G. , Muir Andrew V. G. , Richards Stuart N.
Published: March 2011

Catalytic chain transfer polymerisation of methyl methacrylate has been investigated by a range of cobalt(II) complexes. The effect of catalyst structure, reaction temperature and solvent has been examined. At 60°C in the absence of solvent, the chain transfer coefficient, Cs, for MMA and cobaloximes modified by bridging BF2 groups e.g. 3 is found to be 40,900, this is constant over a wide mass range. Cs is lowered when catalysts of larger cross sectional area are used supporting a diffusion controlled process. Co‐ordinating solvents suppress Cs by competing for coordination of the Co(II) effectively reducing the concentration of active species. No conclusions can be drawn regarding the effect of temperature and thus the activation energy of the process. CCTP lowers the observed rate of polymerisation.
Local monomer concentrations in emulsion polymerization
Authors: German Anton L. , Manders Bart G. , Zirkzee Hennie F. , Klumperman Bert , van Herk Alex M.
Published: March 2011

Knowledge of local monomer concentrations in the case of heterogeneous polymerizations is extremely important, since these local concentrations determine the kinetics of the reactions. In this paper two techniques to determine the local concentrations are reported. The first technique makes use of the well known pulsed initiation method, which is frequently used nowadays for the experimental determination of the propagation rate constant (kρ). The second technique is applied for the determination of monomer concentrations in vesicle bilayer structures.
Optimal sensor selection for copolymerization processes
Authors: Penlidis Alexander , Duever Thomas A.
Published: March 2011

The objectives in this paper are to evaluate several optimal methods for selecting sensors, to exemplify the sensor selection issues that can be addressed using our approach, to critically study sensor selection methodologies and to draw practical prescriptions for their use in general and, more specifically, for copolymerization processes.
Propagation and termination processes in free radical copolymerization
Authors: Fukuda Takeshi , Ide Nobuhiro , Ma Yung‐Dae
Published: March 2011

The propagation and termination processes in free radical copolymerization were discussed on the basis of current experimental data. It was shown that the penultimate unit effect (PUE) in propagation is very general, affecting not only the absolute values of the rate constant but also the monomer reactivity ratios r1 and r2. The analysis suggests that the alternating index r1r2 originates in the PUE. An adequate description of the termination process also requires a penultimate model, which leads to a general, yet simple two‐parameter rate‐of‐copolymerization equation with PUEs in both propagation and termination.
Inversion of phase continuity during polymer‐polymer blending: Effect of processing parameters
Authors: Sundararaj Uttandaraman
Published: March 2011

The melting order of polymer blend components influences the morphology development during extrusion. An inversion in phase continuity occurs during processing if the minor component softens first. Additional power input is required to process the blend due to this inversion. The power input is intensified and the inversion is delayed when a reaction occurs during blending. Increasing the concentration of the minor phase or decreasing the mixer shear rate delays the inversion.
Metastable mesophases
Authors: Wunderlich Bernhard
Published: March 2011

Mesophases are briefly summarized and defined on a uniform basis, making use of order and mobility parameters. A schematic one‐component phase diagram is then reviewed that includes equilibrium as well as nonequilibrium phases. Assuming only five condensed phases (crystal, melt, glass, mesophase, and mesophase glass), fifteen different phase areas exist with simultaneous presence of up to three phases. Examples of all phase areas are documented with results from our laboratory. This scheme can be extended to more components and more than these five phases and produces then many more possible phase areas than can be handled experimentally at the present.
Conformational transitions in macromolecules of complex chemical structure during liquid crystalline ordering
Authors: Volchek Boris , Shilov Sergej , Purkina Alla , Medvedeva Darja
Published: March 2011

Conformational transitions in thermotropic main‐chain polymers of complex chemical structure including homopolymers with possibility of conformational transformations in mesogens and random copolymers (CPLs) containing mesogens of the same type and spacers of different lengths were investigated. It was demonstrated that liquid crystalline (LC) state influences conformational transformations in fragments of chain restraining them in comparison with an isotropic melt. It was found that CPLs studied form LC order of smectic type. Peculiarities in spacers behaviour during transition to LC state ensure formation of such type of LC order. Conclusion about dependence of mechanism of smectic LC order formation on chemical structure of rigid components of CPLs is made.
Ground‐state description of the adsorption of homodisperse and polydisperse polymers
Authors: Fleer G.J.
Published: March 2011

A ground‐state approximation (GSA) is employed to model the structure of an adsorbed layer of homodisperse and polydisperse polymer. The model uses the basic assumption that the volume fraction at a distance z from the surface of a component with chain length N can be written as the product of the square of an eigenfunction g(z) and the N‐th power of an eigenvalue eϵ. This approximation implies the neglect of end effects (tails): only loops are considered. For a homodisperse polymer, the eigenvalue is defined through ϵN = In(1/ϕb), where ϕb is the bulk solution concentration. The eigenfuction can be written in terms of two parameters: a “proximal” length D which through the boundary condition may be related to the adsorption energy, and a “distal” length which is inversely proportional to √ε. For a polydisperse polymer, D is the same as for a homodisperse polymer, but ε has to be computed from an implicit equation which involves a summation over all chain lengths present. The contribution of each chain length N in a mixed adsorbed layer is obtained by weighting with eεN.

This approximate analytical model gives results which are in good agreement with numerical self‐consistent‐field calculations. Examples are given to illustrate the applicability of the model to polydisperse systems. These include adsorption preference of long chains in polymer mixtures and the difference between adsorption and desorption isotherms in polydisperse systems. Simple expressions are obtained for the chain length characterising the transition between (long) adsorbed and (short) non‐adsorbed chains and for the width of the transition zone.
Polymerization of the 12‐methacryloyloxydodecanoic acid and a corresponding phospholipid in monolayers at the liquid/gas interfaces
Authors: Zaitsev S.Yu. , Baryshnikova E.A. , Vereschetin V.P. , Zubov V.P.
Published: March 2011

The following surface‐active monomers with methacrylic group at the end of hydrophobic tail: 12‐methacryloyloxydodecanoic acid (12‐MAODA) and 12‐(methacryloyloxydodecanoyl)‐glycerophosphatidylcholine 12‐MAODPC) were synthesized and investigated. Both monomers are forming monolayers at the liquid/gas interfaces with liquid‐expanded and liquid‐condensed states at low and high surface pressures, respectively. These monomers have been polymerized in the monolayers just by soft UV‐irradiation (254 nm). Dependences of polymerization rate vs. surface pressure for both monomers have maxima (3.33*10−4 s−1 for 12‐MAODPC and 4.89*10−4 s−1 for 12‐MAODA) at about 8–10 mN/m. The higher polymerization rate of 12‐MAODA polymerization as compared to 12‐MAODPC is due to the more dense packing of the acid molecules in monolayers as compared to the lipid. Areas per monomer unit in the obtained polymeric monolayers are much smaller than those for the monomer one. The collapse pressures increase after monomer polymerization that evidences the increase of the monolayer stability in case of polymer as compared to monomer.
Diblock copolymer nanostructures
Authors: Liu Guojun
Published: March 2011

Polystyrene‐block‐poly(2‐cinnamoylethyl methacrylate) (PS‐b‐PCEMA) and poly(acrylic acid)‐block‐poly(2‐cinnamoylethyl methacrylate) (PAA‐b‐PCEMA) were synthesized. These polymers formed micelles with PCEMA as the core in solvents poor for the PCEMA block but good for the other blocks. When the PS block was much longer than the PCEMA block, star micelles were prepared. The PCEMA cores of these micelles were then photo‐crosslinked to yield PS star polymers. Nanospheres of PCEMA were obtained by photolyzing crew‐cut micelles of PAA‐b‐PCEMA, in which the water‐soluble PAA block was much shorter than the water‐insoluble PCEMA block.

PS‐b‐PCEMA self‐assembled at silica and their THF/cyclopentane micellar solution interfaces to form diblock monolayers called polymer brushes, in which the insoluble PCEMA block spread like a melt on the silica surface and the chains of the soluble PS block stretched into the solution phase like bristles of a brush. By tuning the relative composition, PCEMA in bulk formed cylindrical micro‐domains dispersed in the continuous PS matrix. Irradiation of the PS‐b‐PCEMA brushes enabled our preparation of crosslinked PS‐b‐PCEMA monolayers. Nanofibers were prepared by dissolving in THF the irradiated PS‐b‐PCEMA films with crosslinked cylindrical PCEMA micro‐domains.
Polymer‐solvent complexes in thermoreversible gels and in solids as studied by NMR and other methods
Authors: Spêváček Jiří , Suchopárek Miloš
Published: March 2011

The existence of polymer‐solvent complexes, very probably of the inclusion type, was proved in gels and solids of syndiotactic poly(methyl methacrylate) (PMMA), in gels of isotactic PMMA, and in poly(vinyl chloride) gels by NMR spectroscopy combined with DSC and infrared measurements. For PMMA‐solvent complexes, the stoichiometry was estimated. NMR was also used to characterize the dynamic structure of the crystalline intercalate complexes of poly(ethylene oxide) with p‐nitrophenol and other hydroxybenzenes.
Polymers for electrochemical devices
Authors: Sanchez Jean‐Yves , Alloin Fannie , Benrabah Djamila , Roux Christcl
Published: March 2011

Polymeric materials are already present in electrochemical storage devices such as batteries and PEM fuel cells. The polymer is an electro‐active material in lithium polymer batteries. Several network based polymer electrolytes provide thermal, mechanical and redox stabilities, while insuring a high conductivity level. Linear unsaturated polyether precursors may be obtained either by step‐growth polymerization from oligomeric polyethers, or by ring‐opening polymerization from oxirane mixtures. Some prototype performances, performed on a 10 Wh lithium polymer cell, are presented and discussed.
The role of polymer‐solvent compounds in thermoreversible gelation
Authors: Guenet J.M.
Published: March 2011

The definition of a thermoreversible gel is first discussed through the use of two criteria dealing with topology and with thermodynamics. According to this definition only fibrillar systems, as opposed to spherulitic packings, ought to be considered gels. A simple mechanical test is presented that helps recognize such gels. The gelation mechanisms are briefly reviewed and the importance of the role of the polymer‐solvent compound in preventing chain from folding, which favours fibrillar structures, is stressed. Also, the role of such compounds in gel ageing, particularly in the case of PVC, is highlighted.
Ciliation and lamellae in crystalline polymers
Authors: Bassett DC
Published: March 2011

Molecular cilia, the uncrystallized portions of chains already partly attached to polymer crystals, exert a profound influence on the course of polymeric crystallization with ultimate responsibility for the divergence of adjacent lamellae which leads to spherulitic growth. Their effective size and pressure have been measured, in α‐polypropylene, from electron microscopic measurements of the separation and maximum curvature of lamellae in row structures. That cilia exist and extend the effective region occupied by a lamella beyond the geometrical confines of its fold surfaces is important for crystallization theory and may well have implications for the connection of lamellae into networks and for gelation.
The salt effect over the physical interactions occurring for schizophyllan in the presence of borate ions
Authors: Grisel Michel , Muller Guy
Published: March 2011

Schizophyllan solutions in the presence of borate ions were studied in order to evidence physical interactions occurring in aqueous media. The experiments were conducted using viscometric measurements. Changing the added salt was found to have a dramatic effect on the properties of the solutions, and the results were interpreted in terms of water structure variations.
Solvent‐polymer interactions in associative polymer/aqueous media systems
Authors: Picton Luc , Muller Guy
Published: March 2011

Light scattering measurements in the dilute regime (C<C*) of the amphiphilic hydrophobically modified hydroxyethyl cellulose (HMHEC) have shown a metastable equilibrium of solubility in pure water. As a consequence such ageing solutions present a great instability and in severe conditions of added NaCl or temperature, a demixion has been evidenced. In a more concentrated range of concentration, aqueous solutions of HMHEC possess higher viscosity than HEC precursor due to intermolecular hydrophobic associations. But in a 1M NaCl/ethanol mixture this effect is greatly weakened.
Ternary complexes in agarose gels prepared from binary solvents
Authors: Ramzi Mohamed , Guenet Jean‐Michel , Rochas Cyrille
Published: March 2011

The thermoreversible gelation of agarose has been investigated in four different aqueous binary solvents: Water/dimethyl sulfoxide, water/N,N‐dimethylformamide, water/N‐methylformamide, and water/formamide. The phase diagrams have been subsequently established as a function of agarose concentration and solvent composition. These diagrams suggest the formation of ternary complexes agarose/water/cosolvent.
Study of metal clusters intercalation into cellulose by waxs, spectroscopic, and microscopic methods
Authors: Kotelnikova N.E. , Paakkari T. , Serimaa R. , Wegener G. , Kotelnikov V.P. , Demidov V.N. , Schukarev A.V. , Windeisen E. , Knozinger H. , Kudryashov V.I. , Serebryakov A.S.
Published: March 2011

Cellulose substrates are increasingly used as supports and fillers in medicine, as membranes and components of organic sensors. In the present paper the WAXS as well as SEM, TEM, XRF, EDXA, ESCA, FTIR, Raman, and 13C NMR were used to study methods of metal clusters intercalation (taking as an example silver clusters) into the cellulose matrix and changes of cellulose structure in the resulting samples in bulk after this intercalation. Clusters in matrix can be formed simultaneously with the appearance of the metal phase proper on the cellulose surface. Some paths for intercalation of regularly distributed highly dispersed metal particles are shown.
Crystalline structure of PEO‐hydroquinone and PEO‐2‐methylresorcinol molecular complexes
Authors: Paternostre L. , Damman P. , Dosière M.
Published: March 2011

This paper deals with the calorimetric study of PEO‐hydroquinone and PEO‐2‐methylresorcinol complexes. The phase diagrams determination and the evaluation of the exact stoichiometry of both binary systems has been carried out. For the PEO‐2‐methylresorcinol system, WAXS experiments have been used to clarify the phase diagram.
Synthesis of poly(oxypropylene)‐lithium bis(trifluoromethyl‐sulfonylimide) polymer electrolytes. Diffusion study by NMR techniques
Authors: Roux Christel , Gorecki Wladimir , Sanchez Jean‐Yves , Belorizky Elie
Published: March 2011

High molecular weight polymers have been prepared by ring‐opening polymerization of propylene oxide PO using a Vandenberg initiator. Polymer electrolytes based on this polymer and an imide salt LiTFSI have been investigated. We present the results concerning the synthesis of the polymer and the glass transition temperatures evolution of the complexes with respect to salt composition. Diffusion constants of 19F and 7Li nuclei are determined by NMR techniques and a value of the cationic transport number t+ = 0.1 is obtained.
On the clathrate forms of syndiotactic poly(p‐methylstyrene)
Authors: Dell'Isola Annamaria , Floridi Giovanni , Rizzo Paola , de Ballesteros Odda Ruiz , Petraccone Vittorio
Published: March 2011

A classification for clathrate structures of syndiotactic poly(p‐methylstyrene) in two classes (α and β), on the basis of X‐ray diffraction analyses as well as of the different observed behavior with respect to the thermal and acetone treatment, is presented. A structural correlation between α and β class clathrates and forms I and II, respectively, is evidenced. It is also suggested that form I and form II could be the “emptied forms” of the α and β class clathrates, respectively. Similar steric hindrance of the molecules inducing clathrate structures, within each class has been observed.
On the gelation rate of thermoreversible poly(vinylidene fluoride) gels in glyceryl tributyrate
Authors: Mal Sukumar , Nandi Aran K.
Published: March 2011

The gelation rate of poly(vinylidene fluoride) (PVF2)/glyceryl tributyrate (GTB) system has been measured. It has been analysed with the help of an equation which contains φn and f(T) term where φ is a reduced overlapping concentration and n is analogous to the percolation exponent β in a three‐dimensional lattice. f(T) is related to the temperature function of the coil‐to‐helix transition. Analysis of the gelation rates supports that the three‐dimensional percolation is a suitable mechanism in this gelation process and it also indicates that the gelation is caused by coil‐to‐helix transition followed by their association.
NMR determination of the ordering of the molecules in cholesteryl esters liquid crystal phases
Authors: Andreev Vladimir A. , Oleynikova Irina V.
Published: March 2011

A procedure based on the method of moments of NMR line is applied to determine the order parameter tensor for cholesteryl esters. The order parameter dependence on the length of alkyl chain is obtained. The proposed method can be used to estimate the concentration of two independent conformations.
Etude rheologique de gels mixtes de poly(alcool vinylique) et d'alginate de sodium
Authors: Christelle Desmarquet , Eliane Fabrègue , Geneviève Cassanas , Michel Vert
Published: March 2011

Snake‐cage hydrogels were prepared by the association of poly(vinyl alcohol) (PVA) and sodium alginate. The aim of this work is to study the viscoelastic properties of PVA networks having different molecular weights and trapping alginates of various mannuronate/guluronate ratios, molecular weights and aqueous concentration. The elastic and viscous moduli, G′ and G″, were found to depend on alginate concentration. With the sodium alginate (mannuronate/guluronate =1.78, M̄w=380 000), the elasticity was observed to be independent of the PVA molecular weight in the 7.5% to 10% (w/w) concentration range. Hydrogels elasticity was found to be sodium alginate nature‐dependent only in the case of PVA with M̄w =22 000. Moreover, it seems that the viscoelastic parameters G′ and G″ become increasingly insensitive to the nature of sodium alginate as the molecular weight of PVA increases.
Photooxidation of copolymers of fluorinated olefins and allyl or vinyl ethers
Authors: Gardette Jean‐Luc , Posada Fabrice , Philippart Jean‐Louis , Kappler Patrick
Published: March 2011

This article reports the results on the photooxidation mechanisms of two copolymers of fluorinated olefins and allyl or vinyl ethers. It is shown that the presence of the fluorine atoms influences strongly both the orientation of the reaction and the photooxidation kinetics. Due to the neighbouring fluorine atoms, the methylene groups in α‐position of the oxygen of the ether groups are not equivalent regarding oxidation and the secondary carbon becomes more oxidable than the tertiary one. Because these unexpected results were obtained, the study has been extended to non fluorinated polyethers. On the basis of the results obtained, a general mechanism of the primary oxidation of polyethers is given, and the role played by the fluorine atoms on the orientation of the reactions is discussed.
Review and kinetic analysis of the photodegradation of UV absorbers
Authors: Pickett James E.
Published: March 2011

Ultraviolet absorbers (UVA's) undergo photodegradation with quantum yields on the order of 10−6 even in glassy, unreactive matrices such as poly(methyl methacrylate) (PMMA). The kinetics of UVA loss in a film or coating can be described by the equation: A = log10[(1‐To)10 + 1] where A is the absorbance at time t, To is the initial transmission, Ao is the initial absorbance, and k is an “infinite absorption” zero order rate constant. The derivation and implications of this equation and a general review of UVA degradation chemistry are discussed.
On the autoaccelerated character of the branched oxidation of polyolefins
Authors: Verdu Jacques
Published: March 2011

Photochemical or thermal (at moderate temperatures) oxidation of hydrocarbon polymers is characterised by the existence of a pseudo‐induction period, during which oxidation is autoaccelerated, and a steady state. This latter corresponds to the equilibrium between hydroperoxide (POOH) decomposition and formation processes. All the kinetic schemes of thermal ageing, based on the assumption that POOH decomposition is the only source of radicals (whatever its order), have a common feature : the steady‐state rate is independent of the rate constant of POOH decomposition, as experimentally observed in samples containing variable concentrations of catalytic residues.

Experimental data indicate that the duration of the pseudo induction period is proportional to the reciprocal of the POOH decomposition rate constant and independent of any other rate constant. This is an exclusive property of kinetic schemes in which POOH decomposition is unimolecular (whereas termination is bimolecular). The corresponding set of differential equations has been first resolved from the hypothesis of existence of a stationary state for radical concentration. Although this hypothesis is questionable, the corresponding analytical expression appears as a good approximative solution for the general case (no hypothesis of stationary regime). This expression displays interesting predictive properties. Some eventual kinetic implications of spatial heterogeneity of oxidation are examined. Certain variables, for instance the second derivative of the kinetic curve of carbonyl growth (or oxygen absorption), or simply the kinetic curve of mass variation, vary in a non‐monotonous way with exposure time. Consideration of timescale associated to these variations can lead to a quantitative approach of the homogeneity. Schematically, if the characteristic time of non‐monotonous variations is of the order of magnitude of the reciprocal of the rate constant of POOH decomposition or lower, the oxidation can be considered almost homogeneous. In the example under study : experimental data on thermal oxidation of poly(propylene) indicate that these systems are not too far from homogeneous ones.
Stabiliser partitioning and oxidative degradation in rubber‐toughened polypropylene
Authors: Billingham Norman C. , Hoad Oliver J. , Chenard François , Whiteman David J.
Published: March 2011

Solubility measurements on an antioxidant and a UV stabiliser in polypropylene and an ethylene/propylene rubber are correlated with partitioning between the two bulk polymers and between the phases of a blend. At low concentrations, partitioning concentrates the additive in the rubber; the effect increases with temperature, so that most of the additive will be in this phase at processing temperatures. Calculations suggest that the additives can diffuse between phases fast enough to compensate for consumption in either at service temperatures. At processing temperatures, diffusion of antioxidant from the more stable rubber phase to the polypropylene phase may be slow enough to limit protection from oxidation.
Chromatic changes in the blends of electroactive polymers with comb‐shaped flexible polymers
Authors: Kim Myoung Soo , Levon Kalle
Published: March 2011

The effect of blending of alkylated polymers, which have different backbone structures, was investigated in order to improve the electronic properties of conducting polymers. Comb‐shaped flexible polymer, poly(octadecyl acrylate) (PODA), was blended with rigid alkylated conducting polymers, poly(3‐dodecyl‐thiophene)(PDDT), and polyaniline emeraldine base (PANI)/p‐dodecyl‐benzenesulfonic acid (DBSA) complex, respectively, to investigate the effect of long alkyl chain of flexible polymer on the conformational mode change of rigid backbones and the effect of intermolecular interaction between these alkylated polymers. Optical microscopy was applied to observe the morphology change and obtain the phase diagrams of these blends. The intermolecular interactions that occurred in these blends were explained for each different characteristic peak obtained with FT‐IR spectra. Solvatochromism (red‐shift) of PDDT/PODA binary blends in solid state due to the planarity change of rigid backbone in the presence of PODA and electrochromism of PANI(DBSA)4/PODA ternary blends due to the hydrogen bonding between the nitrogen cation of PANI complex and carbonyl group of PODA are observed in UV‐Vis‐NIR spectra. Interestingly, the increase of conductivity was observed in the presence of 5 wt% of PODA in PDDT/PODA binary blends and a homogeneous smectic liquid crystalline structure was clearly confirmed by cross polarized optical microscopy in PANI(DBSA)4/PODA ternary blends.