bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent developments in rubber processing, leading to new applications such as the “green tyre”
Authors: Noordermeer Jacques W. M. 
Published: March 2011

AbstractRubber articles derive most of their mechanical properties from the admixture of reinforcing fillers. Most commonly, carbon black is used as reinforcing filler. If silica is used instead, tyres made with such rubber compounds may exhibit a rolling resistance reduction by ca. 30%, which translates in substantial fuel savings of a car. Such silicas are far more difficult to mix with rubber than carbon black. Coupling agents are used as a surface modification of the filler to enhance compatibility with the polymer. Additionally they improve the ease of mixing with the rubber. The development of proper coupling agents combined with improved mixing techniques has contributed to the final break‐through of the silicareinforced “Green Tyre”.
Thermoplastic composites based on flax fibres and polypropylene: Influence of fibre length and fibre volume fraction on mechanical properties
Authors: Peijs Ton , Garkhail Sanjeev , Heijenrath Rob , van Den Oever Martien , Bos Harriëtte 
Published: March 2011

AbstractNatural‐fibre‐mat‐reinforced thermoplastic (NMT) composites based on flax fibre mats and a Polypropylene (PP) matrix were manufactured using (i) a film‐stacking method and (ii) a paper making process. The influence of fibre length and fibre content on stiffness and strength is reported and compared with data for glass‐mat‐reinforced thermoplastic (GMT) composites, including the influence of using maleic‐anhydride grafted PP. The data is also compared with existing micromechanical models like Kelly‐Tyson and Cox‐Krenchel for strength and stiffness, respectively. A good agreement was found between theory and experiment in case of stiffness while in case of strength the experimental values fall well below the theoretical predictions. Results indicated that NMTs are of interest for low‐cost engineering applications and can compete with commercial GMTs, especially when a high stiffness per unit weight is desirable. Results also indicated that the key area for future development lies not only in improved adhesion but mainly in improving the fibre strength.
Solid‐state processing of phb‐powders
Authors: Lüpke Thomas , Radusch Hans‐Joachim , Metzner Klaus 
Published: March 2011

AbstractPoly(3‐hydroxybutyrate) (PHB) is a completely biodegradable polyester, produced by bacterial fermentation. Because of poor thermal stability, melt processing of the material is accompanied by thermal degradation and poor mechanical properties.To prevent thermal degradation, a solid‐state processing technology has been applied. The extrusion of PHB‐powder at temperatures far below the melting point leads to products of improved mechanical properties. In particular, the ductility of the material increases considerably compared to traditional melt processed PHB. The improved mechanical properties have been attributed to structural differences on the molecular and supermolecular level.
Surface modification of polypropylene: Hydrophilic finishing with carbohydrates
Authors: Knaus Simone , Nennadal Andrea 
Published: March 2011

AbstractConversion of hydrophobic polypropylene surfaces to hydrophilic, water wettable surfaces by adsorption of amphiphilic carbohydrates (“surfactant immobilization”) as well as by covalent bonding of sucrose residues via azid photolysis (“photochemical immobilization”) was investigated. Improvement of surface hydrophilicity was determined by contact angle measurements and application of special test inks for polyolefines.
Polymerization of 1,3‐dienes with neodymium catalysts
Authors: Porri Lido , Ricci Giovanni , Shubin Nikolai 
Published: March 2011

AbstractNeodymium catalysts are typical for the cis polymerization of 1,3‐dienes. The systems prepared from a neodymium‐carboxylate, a chlorine donor and A1(i‐C4H9)3 are characterized by a low efficiency, only ca. 6% of the neodymium being active in the catalysis. Much more active systems are obtained using allyl derivatives of neodymium in combination with aluminoxanes, in particular with methylaluminoxane (MAO). These systems have the characteristics of a single site catalyst. Evidence suggesting an ionic structure for the catalytic species is reported. Terminally substituted butadienes give polymers with a cis‐1,4 isotactic structure, with the exception of (E, E)‐2,4‐hexadiene, which gives trans‐1,4 polymers. An interpretation is reported.
Reactions with samarium diiodide in polymer synthesis
Authors: Vygodskii Yakov S. 
Published: March 2011

AbstractReactions induced by Sml2, such as reduction, coupling and cyclization are occurring in high yield upon mild conditions. It is due to the high redox potential of divalent samarium. Now reactions with Sml2 are used in the polymer synthesis as well. By the coupling reaction of various diacid chlorides poly‐α‐diketones having molecular weight up to 20000 have been obtained at room temperature in quantitative yield. Isomeric difluorobenzils prepared by the one‐step reaction of Sml2 and relevant fluorobenzoyl chlorides have been used in the nucleophylic substitution reaction with bisphenols. Film‐forming high molecular weight copolyetherketone‐α‐diketones have been synthesized when such difluorobenzils have been used as the comonomers in the polycondensation of 4,4'‐difluorobenzophenone and bisphenols. All these polymers bearing α‐diketogroups have been transformed into linear and network polyquinoxalines by their reaction with aromatic (bis)o‐diamines. Aromatic polypinacols have been synthesized by the reaction of dialdehydes and Sml2 in THF under mild conditions. The availability of the reactive α‐hydroxy groups made it possible to carry out polymer chain reactions. It was stated that the imide cycle is reduced by Sml2 at room temperature. The treatment of polyimides by Sml2 leads to the change of polymer properties, mainly heat resistance and solubility. The possibility of formation of Si‐Si bonds by reductive coupling of organochlorosilanes with the use of Sml2 instead of Na has been shown. It was found that the reaction of diorganodichlorosilanes with Sml2 easily proceeds in THF solution at room temperature to yield α,ω‐dichloro‐oligosilanes.
Synthesis of “living” chains of polyvinylpyridine and their application to the construction of homo‐ and hybrid polymer with complex architecture
Authors: Erussalimsky Boris L. , Fedorova Lyubov A. , Klenin Stanislav I. , Shibaev Lev A. 
Published: March 2011

AbstractExperimental conditions ensuring the formation of living poly(2‐ and 4‐vinyl pyridine) chains in the vinyl pyridine ‐ allyl derivatives of chromium, molybdenum and tungsten systems are described. Variation of the reagents nature, polarity of the solvent permits to obtain polymers differing in their structural and molecular parameters. Synthesized polymers contain block and graft sequences, as well as macrocyclic fragments. Living chains under consideration were applied for polymerization of different monomers. Hybrid polymers obtained by this way were studied in detail by the same methods as the homopolymers.
Design and preparation of liquid crystalline block copolymers
Authors: Chiellini E. , Galli G. , Angeloni A.S. , Laus M. 
Published: March 2011

AbstractThe design and preparation of liquid crystalline (LC) block copolymers by use of azo‐macroinitiators are outlined. This approach is very versatile and makes it possible to realize diverse architectures of block copolymers, including non‐LC/side‐chain, non‐LC/main‐chain and side‐chain/main‐chain block copolymers. The different blocks were phase separated and underwent their individual phase transitions. In side‐chain/main‐chain block copolymers different LC mesophases coexisted in equilibrium.
Miscibility of crystalline and amorphous polymers: Poly‐ethylene/polyisobutylene blends
Authors: Szabó Péter , Pukánszky Béla 
Published: March 2011

AbstractBlends were prepared from a linear low density polyethylene and a polyisobutylene in the entire composition range. Flory‐Huggins interaction parameters were determined from DMTA and DSC measurements. The usual technique had to be modified in the case of DSC data, since the Tg of PE cannot be determined by this technique. The two methods yielded identical results and indicated good interaction of the components, which was supported also by a SEM study and the mechanical properties of the blends.
Uniform polyolefin and polymethacrylate
Authors: Hatada Koichi , Kitayama Tatsuki , Ute Koichi , Nishiura Takafumi 
Published: March 2011

AbstractPreparations and properties of synthetic uniform polyolefins and polymethacrylates are described with emphasizing the necessity of their utilization for understanding the fundamental problems in polymer chemistry. Uniform polymer is a polymer composed of molecules uniform with respect to molecular weight and constitution. While classical organic chemistry provides means of constructing uniform polymers such as poly(methylene)s in stepwise manners, recent advances in separation technology such as supercritical fluid chromatography (SFC) have made it possible to isolate synthetic uniform polymers from its homologous mixture. Combinations of stereospecific polymerizations and the SFC technique have enabled us to prepare uniform polystyrenes and poly(methyl methacrylate)s with high stereoregularities, which are very useful for systematic studies on the nature of polymers. The thermal properties of these uniform polymers are discussed in some detail.
Amino acid functionalized ionomeric materials in biomedical applications
Authors: Culbertson Bill M. , Xie Dong , Thakur Alka 
Published: March 2011

AbstractSeveral N‐acryloyl and N‐methacryloyl substituted amino acids have been prepared and copolymerized with acrylic acid and itaconic acid to prepare new polyelectrolytes. Due to an acid‐base reaction, mixing of the water soluble copolymers with glass powders, having leachable Ca2+, Al3+, etc., type cations, produces inorganic‐organic composites hardened by salt ‐bridge formation. These heretofore unexplored polyelectrolytes are shown to be very useful for preparing improved dental biomaterials.
Macromolecular metal complexes with memory to the catalyzed substrate
Authors: Efendiev Aiaz A. 
Published: March 2011

AbstractA number of complexing polymers containing carboxylic, phosphorylic, amine, imine and pyridine functional groups have been prepared and their complexes with copper, cobalt and nickel have been obtained. The complexes were prearranged for reactions of liquid phase oxidation and hydrogenation of hydrocarbons by means of formation and subsequent fixation in memory of the catalysts the structure of active centres favorable for catalyzed substrate. It has been shown that the prearranged complexes might ≤remember≥ the structure optimum for the substrate and this leads to an essential increase in catalytic activity and selectivity of the catalysts.
Two‐phase wacker oxidation of alkenes catalyzed by water‐soluble macromolecular complexes of palladium
Authors: Karakhanov Edward , Filippova Tatyana , Maximov Anton , Predeina Viktoriya , Restakyan Anna 
Published: March 2011

AbstractNew water‐soluble macromolecular palladium complexes with phase transfer ability were used for two‐phase Wacker oxidation of higher alkenes. Macromolecular metal complexes have been prepared employing as ligands monobutyl ether of polyethylene oxide and copolymers of ethylene oxide and propylene oxide functionalized by β,β'‐iminodipropionitrile and acetodinitrile. Macromolecular metal complexes exhibited high activity and selectivity as catalysts for Wacker oxidation of different alkenes: octene‐1, dodecene‐1, hexadecene‐1, styrene, propenylbenzene, cyclooctadiene‐1,5. The complexes based on β,β'‐iminodipropionitrile ligands showed the highest activity. All catalysts can be easily separated from product and used repeatedly without decrease of activity.
Polymeric cobalt‐schiff‐base and ‐porphyrin complexes as a dioxygen device
Authors: Nishide Hiroyuki , Tsukahara Yukihiro , Suzuki Yoko , Tsuchida Eishun 
Published: March 2011

AbstractNew functions of polymeric cobalt complexes were examined using their oxygen‐binding reactions in the solid state. An oxygen‐releasing device was prepared by compositing the oxygen‐binding but electrically insulating cobalt‐Schiff‐base or ‐porphyrin complex with a conductive carbon powder. The device quickly released the absorbed oxygen in response to an applied voltage. A polymer film containing the cobalt‐Schiff‐base complex reversibly stretched in response to the atmospheric oxygen concentration. The driving force of the stretching of the film was attributed to the crystal structure change of the complex before and after the oxygen‐binding.
Nanosize metallodendrimers
Authors: van Veggel Frank C. J. M. , Huck Wilhelm T. S. , Reinhoudt David N. 
Published: March 2011

AbstractBuilding blocks have been designed for the non‐covalent formation of nanosize assemblies. As non‐covalent interactions coordination chemistry and hydrogen bonding have been used. The self‐assembly process leads to spherical assemblies with diameters in the range of 100 to 400 nm, with standard deviations in the order of 10–15%. The controlled assembly approach allows a precise controll of size and assemblies with molecular weights up to 10,000 Dalton have been realized. Finally, we have developed a strategy in which hydrogen bonding and coordination chemistry can be applied “orthogonally”
Model kinetic study of TiCl4‐induced ionization of polyisobutene capped with diphenylethylene application to the synthesis of block copolymers
Authors: Charleux Bernadette , Moreau Michel , Vairon Jean‐Pierre , Hadjikyriacou Savvas , Faust Rudolf 
Published: March 2011

AbstractThe use of non‐homopolymerizable monomers such as 1,1‐diphenylethylene (DPE) in the synthesis of functional polymers and block copolymers by cationic polymerization has been recently reported. The most important parameters in this process, the kinetics and extent of ionization and capping as well as the stability of the cation, were investigated by studying the reaction with TiCl4 of 1‐methoxy‐1,1‐diphenyl‐3,3,5,5‐tetramethylhexane, a model for DPE‐capped polyisobutene chain‐end. This study was performed using 1H NMR and the high‐purity stopped‐flow device coupled with UV‐visible spectroscopy.
Poly(vinyl ethers) as building blocks for new materials
Authors: Goethals Eric J. , Reyntjens Wouter , Lievens Serge 
Published: March 2011

AbstractThe living cationic polymerization of vinyl ethers has been used to prepare a number of new polymers with special properties. Sequential polymerization of the hydrophilic methyl vinyl ether (MVE) and the hydrophobic octadecyl vinyl ether (ODVE) has lead to amphiphilic block‐copolymers with emulsifying properties for water/decane mixtures. Poly(vinyl‐ether) macromonomers were obtained by end‐capping of living polymers with hydroxyethyl acrylate. Copolymerization of polyODVE‐macromonomer with usual acrylates lead to highly branched hydrophobic polymers. When the end‐capping was performed with bifunctionally living polymers, the corresponding “bis‐macromonomers” were obtained. Copolymerization of such bis‐macromonomers with styrene or butyl acrylate, leads to the formation of segmented polymer networks. In the case of polyODVE‐poly(butyl acrylate), these networks showed a pronounced phase separation. Due to the crystallinity of the polyODVE domains, these materials showed shape memory properties.
Open mechanistic problems of quasiliving carbocationic polymerization of olefins mediated by nucleophilic additives
Authors: Iván Béla 
Published: March 2011

AbstractThis study is a comprehensive overview of the open problems and the existing views on the mechanism of quasiliving carbocationic polymerizations (QLCP) of olefins mediated by nucleophilic additives. The fundamental and general aspects of ideal living and quasiliving polymerizations involving other mechanisms, such as free radical, group transfer, ring‐opening metathesis, ring‐opening cationic and anionic processes, have been also analyzed and summarized. Quasiliving carbocationic polymerization of olefins in the presence of nucleophiles, which form complexes with the Lewis acid coinitiators, occur By reversible termination. Four different mechanisms have been discussed in this study: (1) reactivity leveling by nucleophiles (“electron donors”); (2) propagation by species with decreased ionicity (“stretched polarized bonds”) mediated by Lewis acid‐nucleophile complexes (LA‐Nu); (3) propagation by classical ion pair and free ion species; (4) proton scavenging by nucleophiles and 2,6‐di‐teri‐butylpyridine proton trap. It is shown that mechanisms No. 1, 3 and 4 cannot explain all the existing findings, and although the experimental results can be interpreted with mechanism No. 2, the existence of “stretched polarized bonds” can be questionable. It is also concluded that compared to nonliving carbocationic polymerization, kinetic analysis indicates that the propagating species cannot be the same in quasiliving carbocationic polymerizations and in chain transfer dominated classical carbocationic polymerizations with ion pairs and free ions.
Transformation of “living” carbocationic and other polymerizations to controlled/“living” radical polymerization
Authors: Matyjaszewski Krzysztof 
Published: March 2011

AbstractTransformation of “living” carbocationic polymerization of styrene and isobutene to controlled atom transfer radical polymerization (ATRP) is described and formation of the corresponding AB and ABA block copolymers with styrene (St), methyl methacrylate (MMA, methyl acrylate (MA) and isobornyl acrylate (IBA) was demonstrated. A similar approach was applied to the cationic ring opening polymerization of tetrahydrofuran leading to the AB and ABA block copolymers with St, MMA and MA using ATRP. Site transformation approach was also used for the ring opening metathesis polymerization of norbornene and polycondensation systems using polysulfone as an example. In both cases, AB and ABA block copolymers were efficiently formed with styrene and acrylates.
Specific solvent effects of dioxane and N,N,N′,N′‐tetramethylethylenediamine in the anionic polymerization of styrene with Li+ as counterion
Authors: Bastiaens Jos , Huyskens Pierre , van Beylen Marcel 
Published: March 2011

AbstractThe anionic propagation of living polystyryllithium shows a distinctly different behavior depending on the nature of the solvent used (polar or non‐polar). To demonstrate the transition of one type of behavior to the other, studies have been carried out in the past in mixtures of benzene and tetrahydrofuran (THF) and mixtures of dioxane and THF.
Synthesis of homo‐ amd block copolymer multi‐armed methacrylic star polymers by triisobutylaluminium/tert‐butlyllithium initiation
Authors: Crossman Martin C. , Haddleton David M. 
Published: March 2011

AbstractMethacrylate star polymers were prepared using the “arm‐first” strategy of star polymer formation by the addition of ethylene glycol dimethacrylate to living linear poly(methacrylate) arms synthesised by a trialkylaluminium/alkyllithium initiating system Control over star molar mass is discussed for poly(methyl methacrylate) armed star polymers as is the preparation of star polymers with block copolymer arms.
Novel initiating systems for the living polymerization of acrylates and methacrylates
Authors: Schlaad Helmut , Schmitt Bardo , Müller Axel H. E. , Jüngling Stephan , Weiss Horst 
Published: March 2011

AbstractThe polymerization of methyl methacrylate with lithiated initiators in the presence of aluminium alkyls in toluene has living character but it deviates from conventional first‐order kinetics and the polymers have fairly broad molecular weight distributions. This results from the formation and precipitation of a coordinative polymer network in which the lithium ions of the living chain ends are coordinated to the in‐chain ester carbonyl groups. Thus, the network formation can be prevented by adding Lewis bases like methyl pivalate which coordinate to the living chain ends instead of the polymer. Alternatively, one can introduce tetraalkylammonium salts aiming at an exchange of the lithium ion by a less electropositive cation. Both approaches lead to linear first‐order time conversion plots for the polymerization of methacrylates and acrylates and to narrow molecular weight distributions, i.e., to a living and controlled polymerization. With these new initiating systems, various block and graft copolymers can be synthesized.
Living anionic polymerization of (meth)acrylic esters: New mechanistic concepts and resulting materials
Authors: Teyssié Philippe , Baran Janusz , Dubois Philippe , Jérǒme Robert , Wang Jin‐Shan , Yu Jianming , Yu Yisong , Zundel Thomas 
Published: March 2011

AbstractAs an illustration of the frantic development of (meth)acrylic esters anionic polymerization during the last decade, three significant breakthroughs will be presented and analyzed:— extension of the LAP (ligated anionic polymerization) concept to the practical synthesis of both high iso‐ or syndio high MW PMMA;— the production of “perfect” hydrocarbon gels from tailored PMMA‐polybutadiene‐PMMA triblock copolymers;— the use of reactivity “boosters” allowing to climb back up the nucleophilic reactivity scale, i.e. initiating styrene, dienes and (meth)acrylates polymerization with alcoholates and silanolates.
Enzymatic ring‐opening polyaddition for chitin synthesis: A cationic mechanism in basic solution?
Authors: Kiyosada Toshitsugu , Shoda Shin‐Ichiro , Kobayashi Shiro 
Published: March 2011

AbstractThe in vitro synthesis of chitin via a nonbiosynthetic path has been achieved for the first time by enzymatic ring‐opening polyaddition of a chitobiose oxazoline monomer (C2O). Chitinase, a hydrolysis enzyme of chitin, recognized and polymerized the monomer regio‐ and stereoselectively. The structure of artificial chitin was confirmed by comparison with an authentic natural chitin sample with the use of CP/MAS 13C NMR and IR spectroscopy. X‐ray diffraction as well as NMR analysis showed its crystal structure of α‐chitin. Characteristic features of the present polymerization are described.
Intra‐ and intermolecular chain transfer to macromolecules with chain scission. The case of cyclic esters
Authors: Penczek Stanislaw , Duda Andrzej , Szymanski Ryszard 
Published: March 2011

AbstractChain transfer to macromolecules with chain scission is the most often observed “side” reaction in the polymerization of heterocyclics. In our previous works we analysed quantitatively the intramolecular chain transfer to the own macromolecule (back‐biting). This paper gives a general treatment of the kinetics of polymerization with propagation and intermolecular chain transfer to macromolecules, accompanied with chain scission. The numerical solution developed allows determining the kp/ktr ratio from the dependence of m̄w/m̄n on monomer conversion. This treatment was applied to the polymerization of L,L‐lactide and kp/ktr ratios were measured for covalent alcoholate active species bearing Al, Fe, Ti, Sm, and La. In this way selectivities of active species (expressed with kp/ktr) were for the first time measured and finally correlated with the atomic number of the corresponding metal atoms, related to the strength of the bond involved in the monomer addition.
Alkali metals plus complexants: From alkalides and electrides to aromatic anions
Authors: Dye James L. 
Published: March 2011

AbstractElectron transfer from an alkali metal to a suitable complexant for the cation can yield crystalline ionic solids that contain the complexed cation and either an alkali metal anion (alkalide) or a trapped electron (electride). The nature and properties of electrides are emphasized in this paper. When the organic complexant contains aromatic groups, the anionic species is an aromatic radical anion. Preliminary work on the addition of alkali metals to LOGEAs (large organic globular electron acceptors) is described and strategies for the synthesis of mixed electride‐anion compounds are considered.