bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymer dispersions ‐ nanoparticles for everybody
Authors: Müller‐Mall Rudolf
Published: March 2011

Polymer Dispersions are solving many problems of daily life. Nearly everybody is using them as an essential part of waterborn paints, adhesives, paper coating etc. For scientists, polymer dispersions are of growing interest. In this contribution a model for the film formation mechanism is proposed which is based on neutron scattering (SANS), mechanical measurements, and modelling of polymer dispersions.
Poly(3, 4‐ethylenedioxythiophene): Conductive coatings, technical applications and properties
Authors: Jonas Friedrich , Krafft Werner , Muys Bavo
Published: March 2011

Poly(3, 4‐ethylenedioxythiophene) (PEDT) is a new polymeric organic conductor which, when combined with polystyrene sulphonic acid, produces a system that can be processed as an aqueous solution and yields effective antistatic coatings for films. The antistatic effect is achieved with coating weights of just a few mg PEDT/m2, resulting in films with a surface resistivity of 106 ω/□.
Preparation of microgels and their industrial application as fluidity controlling agents
Authors: Ishikura Shinichi
Published: March 2011

Microgels, intramolecularly crosslinked macromolecules with sizes of less than 100 nm, were originally manufactured via an emulsion polymerization process involving the use of novel amphiphilic oligomers containing the zwitterion moiety as emulsifiers. Application of microgels as additives to coatings has been studied here. Newtonian flow of an original coating composition was altered to pseudoplastic flow by the addition of microgels. The mechanism of this fluidity alteration was discussed in terms of electron microscopic observation of the coating composition.
Phase separation of polymer blends under shear field
Authors: Han Charles C.
Published: March 2011

The effect of shear flow on phase separation in critical polymer blends has been studied. For a low‐molecular‐weight blend, the response is in good agreement with the theoretical predictions of Onuki and Kawasaki. The breakup of large‐scale critical fluctuations by the flow leads to a drop in the temperature Tc at which phase separation begins. For a high‐molecular‐weight blend, the data suggest that the mode‐coupling contribution to the decay rate of composition fluctuations is significant in both the miscible and immiscible phases. However, the lack of change of structure factor in the vorticity direction implies that there is no apparent shear induced shift in Tc.
Advanced materials by functionalization of conjugated polymers
Authors: Shimidzu T. , Iyoda T. , Segawa H.
Published: March 2011

Applications of conjugated polymers to advanced materials are demonstrated with fabrications of functional molecular materials and devices by incorporation of functional molecules to conjugated and/or conducting polymer, ultrahigh anisotropic conducting polymer materials by topological polymerizations of LB multilayers of amphiphilic pyrrol, artificial conjugated polymer superlattice by the potential‐programmed electro‐polymerization and/or electrocopolymerization, and 1‐dimensional and 2‐dimensional porphyrin arrays connected with conjugated and/or insulating molecular wires with P(V) porphyrin and others, for molecular photonics and electronics.
Polymeric arrays for directional energy and electron transfer
Authors: Fox Marye Anne
Published: March 2011

Conformationally rigid block copolymers prepared by alkyllithium‐initiated polymerization of vinyl arenes, by molybdenum amide catalyzed ring‐opening metathesis polymerization of chromophore‐labeled norbornenes, and by nickel catalyzed polymerization of functionalized isonitriles are described. Steady state and time‐resolved spectroscopic methods have been employed as tools for the structural characterization of these polymers and for studying the kinetics of long distance electron transfer.
Design and control of morphology for high performance polymer alloys
Authors: Narisawa Ikuo , Kuriyama Takashi , Schemer Bernd , Friedrich Klaus
Published: March 2011

Ductile polymers are significantly toughened by the addition of an elastomeric phase. The rubber phase acts as a stress concentrator, cavitates during the loading process and initiates localized plastic deformation in matrix. This paper deals with the simulation of the deformation behavior of rubber toughened polycarbonate and the fracture process of the embedded rubber particle. A two‐dimensional one particle‐ and two‐particle model with varying surface‐to‐surface interparticle distances are established. The calculation showed that the polymer matrix has plastically deformed before cavitation for the one‐particle model whereas cavitation occurs in the elastic state of the matrix for the two‐particle model. Cavitation itself is proved to be a change from the particle‐system towards a void‐system for both cases. The toughness of the post‐cavitated void‐system is shown to be dependent on the surface‐to‐surface interparticle distance and the strain‐hardening characteristic of the matrix polymer.
Structure and properties of new olefin polymers
Authors: Todo Akira , Kashiwa Norio
Published: March 2011

The relationship between molecular structures and physical properties of linear low density polyethylenes (LLDPEs) produced with single‐site catalyst (SSC) was investigated. SSC polymerized LLDPE have excellent physical properties corresponding to its homogeneous molecular structure that had never been achieved by conventional Ziegler‐Natta catalysts. It was found that some SSCs have the capability to produce LLDPEs with narrow molecular weight distribution but excellent melt properties. This result suggests that there exist long chain branches in these LLDPEs.
Electronic transport in sigma conjugated polymers
Authors: Abkowitz M. A. , Stolka M.
Published: March 2011

Time resolved transport studies which have now been carried out on representative alkyl and aryl substituted Si and Ge backbone polymers demonstrate that these unipolar systems to transmit holes through the specimen bulk with negligible loss of carriers to deep traps, making these materials attractive candidates for electronic device applications. Transport has been studied by measuring drift mobilities as a function of field, temperature and composition, using the small signal time‐of‐flight technique. Transport occurs among chain backbone derived states, yet exhibits behavior essentially identical to systems in which transiting carriers are known to undergo thermally activated tunneling transitions among discrete molecular sites. Thus it is suggested that disorder causes the chain backbone to be suborganized into domain like units of varying conjugation length. The sensitivity of transport to large scale thermodynamic processes, to side group substituent and to the effect of specific dopants is demonstrated.
Polyions for biocompatible materials
Authors: Barbucci Rolando
Published: March 2011

Starting from the thermodynamic properties of some polyamidoamines, showing a protonation behaviour similar to that of small molecules, a relationship with the ability to form polymer‐polymer complexes with heparin or heparin‐like macromolecules was found.

In the light of these results, new heparinisable materials (PUPA and EVAPA) were synthesised, and the surface and bulk structures were understood on the basis of the enhanced hydrophilic characters when these materials are protonated at physiological pH.
Surface modification of polymers: Physical, chemical, mechanical and biological methods
Authors: Hoffman Allan S.
Published: March 2011

The principal objectives and methods of surface modification of polymers are reviewed in this paper. The techniques covered include physical, chemical, mechanical and biological methods.
Functionalization of polymer particles—Focusing on affinity latices
Authors: Kawaguchi Haruma
Published: March 2011

Hybrid particles carrying biospecific compounds to bind their complementary components, were prepared and applied for bioseparation and cell activation. Optimal conditions for particle preparation, immobilization of biocompounds and procedure for application stage were discussed.
Hyperbranched polyesters: End group modification and properties
Authors: Brenner Axel R. , Voit Brigitte I. , Massa Dennis J. , Turner S. Richard
Published: March 2011

Several hyperbranched polyesters have been prepared in a one‐pot polycondensation reaction. Molecular weights, viscosities and rheological behavior of these polymers have been characterized. The influence of their terminal groups on the properties and their behavior in blends will be discussed.
Surface active semifluorinated diblock copolymers prepared by group transfer polymerization
Authors: Krupers Maarten J. , Cabelo Fernando M. E. , Möller Martin
Published: March 2011

Diblock copolymers consisting of poly(methyl methacrylate) and poly(2‐perfluorobutylethyl methacrylate) with narrow molecular weight distribution have been synthesized by group transfer polymerization. Different ratios of the PMMA block to the fluorinated block have been prepared. It was found that all polymers are surface active. Critical micelle concentrations are not dependent on the fluorinated block length. Critical surface tensions, extrapolated from Zisman plots and the dispersion force component of the surface energies extrapolated from Girifalco‐Good‐Fowkes‐Young plots were decreasing with increasing length of the fluorinated block.
Molecular mechanism of high strength and stretch of spider dragline
Authors: Termonia Yves
Published: March 2011

A molecular model is proposed for describing the unusual mechanical properties of spider dragline. We find that the high stretch and strength of the semi‐crystalline fiber are due to the small size of the crystallites which create inside the amorphous region a thin interphase with modulus higher than in the bulk.
Synthesis and characterization of new highly selective polyaryloxyphosphazene‐polysiloxane crosslinked copolymer films. Application to the extraction of organic compounds from water by pervaporation
Authors: Bac Alain , Roizard Denis , Lochon Pierre , Ghanbaja Iaafar
Published: March 2011

A series of polyaryloxyphosphazene/polydimethylsiloxane (PABMP/PDMS) crosslinked copolymer films containing various PDMS contents were prepared by platinum‐catalyzed hydrosilylation reaction. The physical morphology of these membranes was characterized by IR, DSC and transmission electron microscopy. Their transport properties were studied by pervaporation of saturated ethyl acetate aqueous solutions at 30°C. Each copolymer film led to preferential permeation of ethyl acetate. Moreover, selectivity and flux proved to be higher than a PABMP membrane, increasing with the PDMS content up to a 70 wt% value. At the maximum point, an aqueous solution of 7 wt% ethyl acetate was concentrated to 97 wt% with a normalized permeation flux of 25 kg/m2.h.
New amphiphilic polymers: Poly(N‐alkylacrylamide‐CO‐vinylpyridinium)
Authors: Damas Christine , Brembilla Alain , Lochon Pierre
Published: March 2011

A series of new amphiphilic polymers containing various amounts of N‐methyl‐4‐vinylpyridinium units as hydrophilic part and N‐dodecylacrylamide or N‐decylacrylamide units as hydrophobic part have been prepared by quaternizing the cognate copolymers. Their behaviour in aqueous solutions has been studied by viscometry, as well as by fluorescence spectroscopy and tensiometry. Results are discussed in detail and a conformational model of the macromolecules at the interface (water/methylcyclohexane) is proposed in relation to the formation of microdomains in the aqueous media.
Intrinsic styrene/maleic anhydride copolymer foam; a new green foaming technology
Authors: Steenbakkers Wim , Wallink Herman , Steuten Hans
Published: March 2011

DSM has developed a new foaming technology based on carbon dioxide released via a controlled chemical reaction through catalyzed decarboxylation of SMA, a copolymer of Styrene (S) and maleic anhydride (MA). This carbon dioxide is thus used as an environmentally friendly blowing agent to generate intrinsically foamed SMA‐based materials. The modulus of the foam exceeds by far (factor of 2–3) the modulus of common thermoplastic foams based on e.g. PS. The tensile strength is also higher (10%). This opens up many opportunities for SMA foams in structural applications. One example is roofliners. SMA has also been successfully applied as a chemical blowing agent (e.g. in combination with ABS) for the production of a high‐density foam on an injection moulding machine or an extruder. In this paper the chemical background, processing, properties and some applications of intrinsically foamed SMA will be discussed.
Application of polyethylene in reconstruction otologic surgery ‐ foil and porous polyethylene
Authors: Borsig Eberhard , Krošlák Milan
Published: March 2011

Low density polyethylene was prepared in the form of foil and porous plate and used as an implant material for otolaryngology. After clinical testing the foil was introduced into reconstruction surgery of middle ear. The porous polyethylene is undergoing the clinical testing. It also shows a promising application in reconstruction maxillofacial surgery. In the course of testing of polyethylene implants no reaction to the implanted foil was observed for any patient.
Polydimethylsiloxanes with amylose side chains by enzymatic polymerization
Authors: Braunmühl Volker V. , Stadler Reimund
Published: March 2011

Maltoheptaonamide modified polydimethylsiloxane was prepared applying a simplified synthetic pathway in the derivatization sequence of the carbohydrate. The products were characterized by 13C NMR and FT‐IR spectroscopy. The glucan side chains of these “sweet siloxanes” were elongated by enzymatic catalysis with potato phosphorylase.
Nanoarchitectures and molecular composites as advanced materials
Authors: Wegner Gerhard
Published: March 2011

A molecular composite is defined as a supramolecular structure in which extended chains are embedded in a continuous matrix of liquid‐like or glassy nature. A nanoarchitecture is obtained via assembly of shape persistent objects to create two‐dimensional or three‐dimensional patterns. These two concepts have been realized by the design of rod‐like, that is shape persistent, backbones to which short and flexible side chains are attached. The latter acts as a solvent skin providing the solubility and processability to the shape persistent backbone elements. The interaction between the solvent skins of the individual rods create a continuous matrix in which the backbone elements are embedded as reinforcing elements.
Approaches to polymer superlattice and molecular device
Authors: Shimidzu Takeo
Published: March 2011

Approaches to polymer superlattice and molecular devices are shown, demonstrating with functional molecule material by incorporation of a functional molecule into the conducting polymer, conjugating copolymer superlattice by a novel potential programmed electro polymerization, ultrahigh anisotropic conductive LB heterolayers, and porphyrin arrays connected with conducting molecular wire and insulating molecular wire.

These results show a practical method to fabricate ultimate functional materials such as molecular device which is the smallest functional material, and quantum functional material which creates a novel nature.
Percolation in carbon black filled epoxy resin
Authors: Schueler Ruediger , Petermann Juergen , Schulte Karl , Wentzel Hans‐Peter
Published: March 2011

The conditions to form a conductive network in carbon black filled epoxy resin were examined. It was found that the formation is controlled by particle‐particle interaction which can be influenced by shear forces or by the ionic concentration of the resin. Therefore the network morphology and thus the percolation threshold depends strongly upon the processing route. On best conditions the percolation threshold was reduced to 0.06 vol.‐%. That a continuous network can form with such a low volume fraction can be explained by the fractal dimension of agglomerates the network is made of.
Disulfide‐polyaniline composite cathodes for rechargeable batteries with high energy density
Authors: Oyama Noboru , Tatsuma Tetsu , Sotomura Tadashi
Published: March 2011

A composite cathode was prepared from a solution containing 2,5‐dimercapto‐1,3,4‐thiadiazole (DMcT) and polyaniline (PAn). The resulting cathode exhibits 80% of the theoretical capacity. Furthermore, an energy density of over 600 Wh/kg‐cathode and a discharge voltage of 3.4 V are obtained, when it is coupled with a lithium anode. Additional advantages of the present cathode material over the conventional metal oxides are the ease in disposal by incineration, the low pollution and the low cost. Current capability of 137 A/kg‐cathode is achieved by adding a polypyrrole derivative to the DMcT‐PAn composite and coupling it with a copper current collector.
Recent advancement of ion‐conductive polymers
Authors: Ohno Hiroyuki , Ito Kaori
Published: March 2011

The inorganic salt‐containing poly(ethylene oxide) is a representative starting system to design high ionic conductors. Higher ionic conductivity is expected to be obtained by the improvement of both or either of carrier ion concentration and carrier ion mobility. The recent approaches to make more excellent ion conductive polymers were classified into three groups, i.e., new salts, new polymer matrix, and new system. Some interesting approaches are also reviewed in this paper.
Metal complexes of partially phosphorylated poly(vinyl alcohol) ‐ functions and applications
Authors: Shirai Hirofusa , Koyama Toshiki , An Ying , Hanabusa Kenji , Hojo Nobumasa
Published: March 2011

The highly phosphorylated poly(vinyl alcohol)s (P‐PVAs: degree of phosphorylation 70 mol‐%) were synthesized by the reaction of PVA, dicyandiamide, urea and orthophosphoric acid in DMF solution. A range of P‐PVAs having differents contents (3.3 to 70 mol‐%) of phosphoric acid groups can be obtained by the change of reaction time via the same procedure. The complex formation of Cr(III), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) ions with P‐PVA thus obtained was investigated by means of potentiometric titration and spectroscopy. By chemical crosslinking reaction of P‐PVA with glutaraldehyde, novel anionic polyelectrolyte gels were easily prepared. The degree of swelling and the hardness of hydro‐gels can be changed by varying the crosslinking reaction condition. The ion exchange capacity and metal ion selectivities of a cation exchange resin prepared from P‐PVA hydrogel have been estimated. Flame‐retardation of metal‐P‐PVA complexes have also studied. The Ni(II)‐P‐PVA complex showed a good flame‐retardation. The molecular composites of the P‐PVA salts of cations such as K+ or R4N+ (R = CH3 etc.) were also prepared. These composite polymers showed single ionic conductivity (σ rt > 10−4 S · cm−1).
Polyelectrolyte‐surfactant complexes: Highly ordered microphase‐separated polymers
Authors: Antonietti Markus , Burger Christian , Conrad Jürgen , Kaul Antje
Published: March 2011

Polyelectrolyte‐Surfactant complexes (PE‐Surfs) represent a new class of microphase‐separated polymers showing a variety of phase modifications with a high degree of supramolecular order. The complexes are simply made by common precipitation from water and are easy to handle. In addition, they exhibit an exciting combination of product properties coming from the surfactant as well as from the polyelectrolyte side. In this article, an overview of the current work on the solid‐state properties of these materials as well as a personal outlook to future trends is given.
Self‐assembly of domain wall of molecular twist defects in polyethylene crystal
Authors: Balabaev Nikolai K. , Gendelman Oleg V. , Manevitch Leonid I. , Mazo Michael A.
Published: March 2011

Two‐dimensional structural defects in a polyethylene crystal (twist domain walls) are investigated by means of analytic treatment and molecular dynamics simulation. The formation of the domain wall as a result of relaxation of the crystal from different initial states is studied and parameters of this type of defects are calculated.
Synthesis and investigation of liquid polyurethane metal complexes
Authors: Davletbaeva Ilsiya M. , Kirpichnikov Petr A. , Rakhmatullina Alevtina P.
Published: March 2011

Polyurethane metal complexes (PUMC's) have been synthesized on the basis of the polynucleus complexes of Cu(II) and Fe(III), where the metals are connected by chlorine bridges, symmetrical aromatic diisocyanates and azoaromatic compounds; these complexes exhibit properties of thermotropic liquid crystals. The mesophase temperatures of the substances range from is 20–80 °C and 60–110°C. Specific electric resistance of the synthesized liquid crystal systems is 103‐105 ω‐cm.
The kinetics laws for polymer collapse and biopolymer folding
Authors: Dawson K. A. , Timoshenko E. G. , Kuznetsov Yu. A.
Published: March 2011

We discuss some recent ideas relating to the folding and other conformational transitions of polymers. In particular we emphasize that it is possible to conceive the accompanying kinetic processes as a problem in non‐equilibrium statistical mechanics. In this sense it should be possible to develop such methods to deduce the kinetic laws in the vicinity of various conformational transitions. To establish the ideas we first study the well known problem of the collapse transition of a homopolymer. We then turn to conformational transitions in periodic and random copolymers. We offer a brief survey of the status of these ideas in applications to biopolymeric conformational kinetics.
Competitive reactions in solutions of DNA‐containing polyelecrtolyte complexes
Authors: Izumrudov Vladimir A. , Zhiryakova Marina V. , Kargov Sergei I. , Zezin Aleksandr B. , Kabanov Victor A.
Published: March 2011

The reaction of competitive binding of two polyanions ‐ DNA and synthetic fluorescence‐tagged poly(methacrylate) (PMA*) ‐ with the quencher polycation poly(N‐ethyl‐4‐vinylpyridinium) (PEVP) was studied by fluorescence quenching technique. It is found that ability of DNA to displace PMA* from water‐soluble nonstoichiometric interpolyelectrolyte complex (NPEC) formed by PMA* and PEVP ‐ NPEC(PMA*‐PEVP) ‐ and to form water‐soluble NPEC(DNA‐PEVP)

magnified image can be determined by both a parameter Ψ = PPMA+/Ppevp, where Ppma+ and Ppevp are the degrees of polymerization of PMA* and PEVP, respectively, and by the nature and concentration of alkali and alkali earth metal cations. According to their ability to shift the equilibrium to the right the cations can be arranged in the series Ca2+ > Mg2+ >> Na+ > K+ > Li+. The data obtained are in accordance with the differences in the selectivity of alkali and alkali earth cations binding with competitive polyanions.
Polymer ultrathin films with immobilized photosynthetic reaction center proteins
Authors: Kalabina N. A. , Zaitsev S. Yu. , Zubov V. P. , Lukashev E. P. , Kononenko A. A.
Published: March 2011

Properties of mixed monolayers of lipid‐photosynthetic reaction center proteins (RC) were studied and the optimum conditions for stable films fabrication were determined. The following synthetic: N‐acryloylphosphatidylethanolamine (ACPE), tetracosa‐11, 13‐diinoic acid (TDA), pentacosa‐10, 12‐diinoic acid (PDA), dioctadecyldienoylphosphatidylcholine (DODL) and natural lipids: L‐α‐phosphatidylethanolamine (PE), L‐α‐phosphatidylcholine (PC) were used. The rate of polymerization of the mixed ACPE‐RC and TDA‐RC monolayers is lower in comparison with corresponding values for pure lipid‐like monomers on air/water interface. The optical and photoelectrical measurements provide evidence for an orientation of RCs on interface. Hydrophilic H‐subunit in monomeric and polymeric ACPE‐RCs, and monomeric DODL‐RCs monolayers is preferentially oriented towards water as in the pure RC monolayers. Opposite orientation was found with TDA‐RCs and PDA‐RCs films. No preferential orientation for lipid‐RCs from C. aurantiacus monolayers was found because of the RCs having low assymmetry of hydrophobic subunits (M and L).
Novel method to form giant liposome entrapping DNA
Authors: Kumazawa Noriyuki , Mel'Nikova Yulia S. , Yoshikawa Kenichi
Published: March 2011

We report a new method to prepare giant liposome with the size of several tens micrometers, entrapping DNA molecule within the closed phospholipid membrane. The formation of such liposomes has been confirmed through the observation with fluorescence microscopy.
A control of primary structure in the products of macromolecular reactions
Authors: Litmanovich Arkady D. , Platé Nicolai A.
Published: March 2011

Basing on the theory of macromolecular reactions, an influence of various factors on a units' distribution (UD) of the forming macromolecules is considered. In diluted solutions UD is determined by a competition between external reagent and intrachain interaction of reacted and unreacted units, first by neighbor effect. Should accelerating action of remote units is commensurable with that of nearest neighbors, such a conformational effect enlarges the formation of alternating sequences. In a melt, interchain effect shifts UD to a random one. In a polymer blend consisting of reacting and non‐reacting but influencing the reactivity components, UD of transforming macromolecules is formed under concerted action of the reaction and interdiffusion. Thus modern achievements of the theory permit to analyze peculiarities of a wide set of reaction systems and facilitate a choice of optimal conditions for the preparation of tailor‐made macromolecules.
Chiral crystallization of helical polymers
Authors: Meille Stefano V. , Allegra Giuseppe
Published: March 2011

Crystallization of achiral or racemic helical polymers in chiral crystals is quite frequent and while in some cases it may relate to the thermodynamic stability of the chiral polymorph, in others it must be associated with kinetic factors. Analysis of the available literature data suggests that in the second instance a key role must be played by the nucleation step, i.e. specifically by the formation of precrystalline entities. Furthermore a survey of the chiral crystal structures for helical polymers evidences that they are frequently characterized by a quasi‐hexagonal packing. The hexagonality index H, defined as the ratio of the largest to the smallest distance between the axis of the reference helix and its six nearest neighbors, appears to be a reliable indicator of the presence of helices of a single handedness or, respectively, of both in a given crystal structure. A detailed analysis of the general energetic and entropic factors favouring chiral crystallization of helical polymers is carried out. It is shown that a hexagonal or pseudo‐hexagonal arrangement (i.e. the six‐fold coordination) in either the crystalline or in a precrystalline state, promotes chiral crystallization and is in its own turn favoured by clustering of isochiral helices.
The polyurethaneisocyanurate morphology
Authors: Zenitova Lubov A. , Bakirova Indira N. , Kirpichnikov Petr A.
Published: March 2011

By catalytic trimerization polyurethaneisocyanurates (PUIC) with varying content of isocyanate and oligoester fragments were obtained. The number of triisocyanurate fragments in the PUIC network was determined with infrared spectroscopy and by using the multiple disrupted complete internal reflection technique. It was also shown that the PUIC resistance to high temperatures improves as the content of triisocyanurate fragments increases.
Coil‐globule transition: Self‐assembly of a single polymer chain
Authors: Chu Benjamin , Wu Chi
Published: March 2011

The coil collapse problem is of interest not only because it represents the simplest model of protein folding, but also because of its fundamental importance as related to polymer nanostructures and fractionation. It is extremely difficult to observe the coil‐to‐globule transition experimentally because at finite concentrations in a poor solvent, the macromolecules tend to aggregate due to phase separation when the collapsed state is being achieved. In the mid‐1980s, two‐stage kinetics of a single‐chain collapse was proposed theoretically.1,2 The first successful experimental observation of a two‐stage coil‐to‐globule transition was achieved by quenching a dilute solution of polystyrene (PS) in cyclohexane.3

By using a thinnest capillary tube cell with a wall thickness of 0.01 mm and a diameter of 5 mm for dynamic light scattering, two relaxation times, τcrum for the crumpled globule state and τeq for the compact globule state, were determined4 for the first time. The relaxation times were much slower than expected. From the size of the crumpled globule and that of the compact globule and by assuming the intraglobular density to be uniform, the volume fraction of the PS chain in the crumpled globule state, ϕcrum, and that in the compact globule state, ϕcomp, can be estimated, with ϕcrum = 0.02 and ϕcomp ∼ 0.24‐0.4 at 28°C for polystyrene in cyclohexane. The results imply that a single‐chain globule contains a large amount of solvent. It should also be noted that ϕcomp is temperature dependent, i.e., one would have to go to hypothetically low temperatures in order to squeeze out all the solvent (cyclohexane) in the compact PS globule.

The single‐chain coil collapse state could be achieved under equilibrium conditions by using a high molecular weight, Mw ∼ 1.08 × 107 g/mol; Mw/Mn < 1.06) poly(N‐isopropylacrylamide) (PNIPAM) in water,<5 even though the ten million molecular weight for PNIPAM was substantially lower than that for polystyrene (Mw ∼ 50 × 106 g/mole).6 Under equilibrium conditions, it was feasible to determine both the hydrodynamic radius Rh and the radius of gyration Rg. The ratio of Rg/Rh changed from 1.45 to 0.77, clearly demonstrating the transition from the theta coil state to the compact globule state. At the maximum value of the scaled expansion factor αs3 |τ| Mw1/2, Rg/Rh = 1.33 where αs = Rg/Rg (θ) and τ = |T‐θ| / θ with θ being the theta temperature. In the compact globule, Rg/Rh was of the order of 0.7, implying that the PNIPAM compact globule in water still contained ∼80% water, of the same order of magnitude as the PS compact globule in cyclohexane at 7° below its theta temperature (35°C).
Molecular recognition phenomena in polyelectrolyte systems
Authors: Kabanov V. A.
Published: March 2011

The term “molecular recognition” is commonly used to describe various specific interactions, sometimes being not well defined. Let's assume that some species A can separately interact with either species B1, or B2, (or B3, B4 etc.) forming A·B1, or A·B2, (or A·B3, or A·B4 etc.) complexes. Here we say “recognition” assuming selective complexation of A with B1 in the mixture containing also B2 (B3, B4… etc.). At the same time it means discrimination of all other B species except B1.
Block polyelectrolytes in aqueous environments
Authors: Khougaz Karine , Moffitt Matthew , Zhang Lifeng , Eisenberg Adi
Published: March 2011

Analogous to the self‐assembly of low‐molecular‐weight amphiphiles in aqueous solutions, the formation of spherical micelle‐like aggregates has been observed in systems of amphiphilic block copolymers in water. The aggregates, often called micelles due to structural similarities with surfactant associates, are found to exist above the critical micelle concentration (cmc). The micellization of amphiphilic block copolymers has been investigated using a wide range of techniques, such as size‐exclusion chromatography (SEC), static and dynamic light scattering (SLS and DLS), small‐angle x‐ray scattering (SAXS), small‐angle neutron scattering (SANS), transmission electron microscopy (TEM), viscometry, and steady‐state fluorescence spectroscopy.

The present lecture is a review of recent work in our laboratory concerning the micellization of ionic block copolymers. These high‐molecular‐weight amphiphiles may contain one or more of a variety of ionic blocks, such as poly(4‐vinylpyridinium alkyl halides), poly(metal acrylates), poly(metal methacrylates) and sulfonated polystyrene. In water, such polymers are referred to as block polyelectrolytes, as they combine the colloidal behavior of block copolymers with the long‐range electrostatic interactions of polyelectrolytes. Early work in this field has been reviewed by Selb and Gallot.1
Anionic polymerization of spiro monomers derived from germylene
Authors: Shoda Shin‐Ichiro , Ohnishi Yasuharu , Yagi Katsuhiko , Kamo Hiroki , Kobayashi Shiro
Published: March 2011

The ring‐opening polymerization of a spiro germanium enolate proceeds smoothly catalyzed by an anionic initiator, giving rise to a poly(germanium acyclic enolate), an organometallic polymer having a germanium enolate structure. The resulting polymers have an O‐germanium enolate unit and a C‐germanium enolate unit in the main chain. Various anionic catalysts including neutral alkali metal salts, methanol, and water initiate the polymerization effectively. The monomer of the spiro germanium enolate is easily prepared in situ by the reaction of a cyclic germylene with methyl vinyl ketone.
Oxetane photopolymerization—A system with low volume shrinkage
Authors: Nuyken Oskar , Böhner Ralf , Erdmann Christoph
Published: March 2011

Several mono‐, bi‐ and trifunctional oxetanes were synthesized and polymerized in bulk and in solution cationically. Selected photoinitiators have been applied. It was found that sulfonium salts are very efficient due to good solubility, almost no discolouration of the product and storage stability in the monomer in the absence of light. The conversion was determined by quantitative IR‐spectroscopy. Conversion between 75% and 85% was found in all cases. The shrinkage during polymerization was much lower than for vinyl monomers. No inhibition by oxygen was recognized. Monomer layers thicker than 5.5 mm could be polymerized. The products are transparent and almost colourless. The glass transition temperature of the crosslinked polymers was above the temperature of a human body.
Synthetic and mechanistic aspects of metal‐free polymerizations of acrylates
Authors: Reetz Manfred T. , Hütte Stephan , Herzog H. Martin , Goddard Richard
Published: March 2011

Metal‐free initiators are easily prepared from neutral CH‐ and NH‐acidic compounds such as malonic acid esters, nitriles, sulfones, nitro‐alkanes, cyclopentadiene, fluorene derivatives, carbazoles and succinimide. These anions have tetrabutylammonium ions as cationic counterions, but they are not completely free “naked” anions as traditionally assumed. Rather, anion and cation are intimately connected to each other via H‐bonds. These salts initiate the polymerization of acrylates, methacrylates and acrylonitrile, forming polymers in the MW range of 1500 to 20000 with narrow molecular weight distributions (D = 1.1–1.4) in optimized cases. A completely different approach involves initiators of the type α‐iodo malonic acid esters CH3C(I)(CO2R)2 and α‐ iodo isobutyric acid esters (CH3)2C(I)CO2R in combination with (nBu)4N+I− at 60°C. This novel initiator system is specific for metharcylates, i. e., acrylates are not polymerized.
Highly heterotactic polymerization of methacrylates — Higher order stereoregulation and stereochemical significance
Authors: Kitayama Tatsuki , Hirano Tomohiro , Zhang Yajun , Hatada Koichi
Published: March 2011

A combination of tert‐butyllithium (t‐BuLi) and bis(2,6‐di‐t‐butylphenoxy)methylaluminium (MeAI(ODBP)2) was found to be an efficient initiator for heterotactic living polymerization of certain alkyl methacrylates in toluene at low temperatures. The polymerization of methyl methacrylate (MMA) with t‐BuLi/MeAI(ODBP)2 (AI/Li=5 mol/mol) in toluene at −78°C gave heterotactic‐rich poly(methyl methacrylate) (PMMA) with narrow molecular weight distributions (MWDs) (heterotactic triad fraction mr = 68%, ratio of weight‐ to number‐average molecular weights M̄w/M̄n = 1.06‐1.17). Other alkyl methacrylates also gave heterotactic polymers under the same conditions; in particular, ethyl and butyl methacrylates gave polymers with heterotactic triad fractions of 87%. The highest triad heterotacticity of 91.6% was obtained for the polymerization of ethyl methacrylate at −95°C. Some characteristic features of this stereospecific polymerization were discussed based on the polymerization results combined with other structural information of the polymer such as chain‐end stereostructure and stereosequence distribution in the main chain.
Multi‐arm star polyisobutylenes: 3. New insight into the chemistry of star formation: Star‐star coupling and core contraction
Authors: Kennedy J. P. , Marsalkó T. M. , Majoros I.
Published: March 2011

Details of the chemistry of linking living polyisobutylene (PIB⊕) pre‐arms with divinylbenzene (DVB) to multi‐arm PIB stars have been studied by triple‐detector size‐exclusion chromatography (SEC). Computer‐aided deconvolution of multimodal differential refractive index (RI), laser light scattering (LLS), and ultraviolet (UV) traces obtained by SEC indicates the formation of complex product mixtures. The observations were interpreted in terms of inter‐and intramolecular reactions of initially‐formed active stars. Thus intermolecular or star‐star couplings are proposed to lead to higher order (secondary, tertiary, etc.) stars, whereas intramolecular reactions result in core‐contraction. The mechanism of these reactions has been outlined. The effect of PIB⊕ pre‐arm length on star‐star coupling was analyzed.
Talc production: An overview
Authors: Robert J. F. , Fragnier P. , Europe Luzenac
Published: March 2011

Luzenac Group, which presently produces and markets more than 1 million tons talc per year, has ensured its international development through the permanent search for a better adequacy between the very specific talc properties of its various deposits and their application in very different industrial fields.
A review on the structure and characterization techniques of silane/matrix interphases
Authors: Suzuki Noriyuki , Ishida Hatsuo
Published: March 2011

Recent studies regarding the interphase of silane coupling agents and organic polymer matrices are reviewed with emphasis on its structure and property, and characterization techniques for the interphase. Chemical, physical and physicochemical effects on the formation of silane/matrix interphase and resultant properties are discussed. Improvements of the performance of composite materials are also discussed in relation to the interphase structure. Several representative characterization techniques for interphase are also described.
Introduction of tailored interphases in composite materials based on a thermoset or on a semi‐crystalline polymer matrix
Authors: Gerard Jean‐François , Chabert Bernard
Published: March 2011

Interphases having different structures can be created in composite materials based on a thermoset or semi‐crystalline matrices. The mechanical behavior of the reinforced or filled polymers is dependent on the characteristics of these interfacial zones. The microstructures of the interphases result from the interactions occuring at the filler surface. For the thermoset matrices, the structure of the interphases (continuous, distinct) is dependent on the chemical reactions between the surface or the sizing and the reactive mixture during the processing. In the case of the presence of a sizing, the miscibility with the polymer matrix can be also involved. For the semi‐crystalline matrices, the melting and cooling conditions are the main conditions but the occurence of a shearing in the supercooled melt can create transcrystalline regions. Another way consists in the introduction of tailored interphases with controlled properties. Coatings or surface treatments based on functionalized polymers can be made on the fillers or fibers before introduction in the polymer matrix. For the thermoset systems, a soft interlayer with a controlled thickness is introduced at the filler surface, whereas for the semi‐crystalline matrices, polymer chains having the same structure than the matrix are grafted on the surface.
Electrical properties of filled polymers and some examples of their applications
Authors: Klason Carl , Mcqueen Douglas H. , Kubát Josef
Published: March 2011

Polymers containing electrically conductive fillers show interesting electrical properties like semiconductors and metals without losing the processability of polymers. Typical applications are as antistatic (electrostatic dissipation) materials, electro‐magnetic interference shielding materials, heaters and sensors. The selection of filler and polymer governs the properties obtained in such composites.
High swelling gels for sensing applications
Authors: Ranucci Elisabetta , Ferruti Paolo , Ferrari Vittorio , Marioli Daniele , Taroni Andrea
Published: March 2011

Crosslinked hydrophilic polymers of different chemical structures can be used as sensor coatings for the detection of gaseous analytes. If their crosslink density is low, these materials behave in aqueous media as soft hydrogels with high swelling capacity. From a physico‐mechanical standpoint, they are amorphous rubber‐like materials, with high flexibility of their macromolecular chains. This property is particularly significant in view of applications in the sensors field, because it favours diffusion of the analyte molecules through the coating layer. This paper deals with the application of poly(ethylene glycols) (PEG)‐ and poly(N‐vinylpyrrolidinone) (PVP)‐based crosslinked resins as relative humidity (RH) sorbing materials, and of a poly(amidoamine)(PAA)‐based resin as SO2‐sorbing material. The electronic devices used for evaluating the sorption capability of these polymeric coatings were gravimetric resonant sensors. Resins of various crosslink density, and therefore of various swelling ratios in water, were purposely prepared and characterized. Thin coating, layers, prepared by casting from dilute aqueous suspensions of the resins, previously micronized in water, were used for sorption experiments. All experiments were performed in controlled RH and temperature environments.
Liquid chromatography techniques for characterizing poly(Vinyl Alcohol)
Authors: Meehan Elizabeth , Reid Simon P. , Samios Eleftherios , Dawkins John V.
Published: March 2011

Poly(vinyl alcohol) (PVOH) samples may contain several heterogeneities requiring the development of chromatographic techniques for characterization. Size exclusion separations have been carried out using a number of aqueous eluents, incorporating electrolyte, or electrolyte/organic modifier, or surfactant. The most favourable molecular size separation was obtained using 0.25% w/v sodium lauryl sulfate as eluent. Reasonable values for molecular weights of PVOH samples have been determined. Compositional distributions in copolymer systems can be assessed using high‐performance liquid chromatography employing a reversed‐phase separation mechanism. For poly(vinyl alcohol), gradient elution with water/tetrahydrofuran (THF) with a wide pore polystyrene‐based packing produced separations dependent on degree of hydrolysis and sequence length distribution. The elution results were verified with a column packed with non‐porous beads. Partially hydrolysed PVOH samples appeared to have a broad distribution of composition.
Some emerging techniques in polymer mwd characterization
Authors: Nguyen Tuan Q. , Yu G. , Kausch H. H.
Published: March 2011

Routine MW analysis of polymers is generally performed in solution by Gel Permeation Chromatography. The technique, however, presents increasing difficulties in the ultra‐high and ultra‐low MW range. Moreover, GPC is not applicable to most fluorinated and»high performance«thermoplastics which require dissolution temperatures close to the polymer melting point. In response to these challenges, polymer scientists have developed new methods of MWD determination. Although these methods have not yet reached the versatility of GPC, they present potential for further development and are interesting as complementary techniques to GPC. For sparingly soluble polymers, melt viscoelastic properties have been used to obtain information on polymer MWD. Flow birefringence, based on the orientation and extension of long flexible molecular chains in a shear field, has been applied to the characterization of ultra‐high MW polymers. For low MW polymers and oligomers, the MALDI mass spectrometry technique, with its unique capabilities to resolve individual oligomers within a MWD, proves to be an interesting alternative to conventional GPC characterization.
Liquid chromatography at the critical point of adsorption — A new technique for polymer characterization
Authors: Pasch Harald
Published: March 2011

Liquid chromatography at the critical point of adsorption (CC) is a versatile method for the determination of different types of molecular heterogeneity in polymers. Operating at the transition point of size‐exclusion and adsorption modes of liquid chromatography, this method is capable of separating polymers according to their functionality. At the critical point of adsorption the polymer chain behaves like an invisible part of the macromolecule and only the heterogeneities (functional groups, blocks, grafts) manifest themselves chromatographically.

The application of this method to the determination of the chemical heterogeneity of block copolymers and the composition of polymer blends is demonstrated. Block copolymers can be analysed with respect to the block lengths of the individual blocks. A complete description of their molecular heterogeneity is possible using two‐dimensional chromatography CC vs. SEC. Binary polymer blends are separated with respect to the components regardless of their individual molar masses under experimental conditions, where one component elutes at the critical point of adsorption.
Composite dextran gels as size exclusion chromatography stationary phases
Authors: Spychaj Tadeusz , Bartkowiak Artur
Published: March 2011

Composite dextran gels have been prepared using epichlorohydrin as the covalent cross‐linker and a modifying agent, typically a polyvalent metal compound creating complexes with the residual OH groups of the polymer matrix. Two series of gels were prepared and investigated by a comparison of their swellabilities in water as well as the separation characteristics when used as size exclusion chromatography (SEC) stationary phases. The gels were in situ modified with sulfates of Mg(II), Zn(II), Co(II), Ni(II), Cu(II), Mn(II), Al(III), Fe(III) and tetraethylorthotitanate or with the oxides: MgO, ZnO, Al2O3, TiO2 and SiO2. Large differences in the swellabilities and SEC calibration dependences for poly(ethylene glycol) standards in an aqueous eluent have been found and discussed.
Molded separation media: An inexpensive, efficient, and versatile alternative to packed columns for the fast HPLC separation of peptides, proteins, and synthetic oligomers and polymers
Authors: Svec Frantisek , Fréchet Jean M. J.
Published: March 2011

A simple molding process carried out within the confines of a chromatographic column has been used for the preparation of macroporous poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) and poly(styrene‐co‐divinylbenzene) rods. The novel monolithic separation media that are obtained are useful for the HPLC separation of biological and synthetic polymers. The presence of large pores with a diameter of about 1 μm makes the molded rod columns easily permeable to eluents. Therefore, the back pressure of these columns is modest even at high flow rates. In contrast to the conventional HPLC columns packed with beads, all of the mobile phase flows through the continuous monolithic medium. As a result of this total convection, the efficiency of the molded media is almost independent of the flow rate. This improves significantly the separation ability of the rod columns and very fast separations of macromolecules such as peptides, proteins, and synthetic polymers have been demonstrated.