bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective hydrogenation of chloronitrobenzenes catalyzed by palladium complex of silica‐supported chitosan
Authors: An Ying , Yuan Ding , Huang Mei‐Yu , Jiang Ying‐Yan 
Published: March 2011

AbstractA palladium complex of silica‐supported chitosan has been found to catalyze the hydrogenation of p‐, m‐ and o‐chloronitrobenzene, and of 4‐chloro‐1,3‐dinitrobenzene to p‐, m‐ and o‐chloroaniline, and 4‐chloro‐3‐aminoaniline in 100% yield, respectively, at room temperature and under atmospheric pressure, and the side reaction, dechlorination, has not been observed. This catalyst was very stable, the turnover numbers (p‐chloronitrobenzene to p‐chloroaniline cycles / palladium atom) reached 9000 in 17 hours.
The effects of structures and compositions of polymer‐metal complexes on the hydroformylation of olefins
Authors: Pan Caiyuan , Zong Huijuan 
Published: March 2011

AbstractA number of linear and crosslinked polymer ligands containing P or N or S as coordinative atoms were prepared. The hydroformylation of olefins was carried out at mild conditions in the presence of complexes as catalysts which were made by complexation reactions of these ligands with various homogeneous complexes or metal salts. The obtained results were explained in terms of the influences of the polymer matrix, or the structures and compositions of the polymer chain, and the properties of polymer‐metal complexes on activity and selectivity. The most important factor for enhancing the selectivity towards linear aldehyde lies in the properties of the polymer‐metal complex. High selectivity up to 95% was obtained by using polymer phosphine ligand‐Pt‐Sn complexes as catalyst in the hydroformylation of olefins. The hydroformylation mechanisms were discussed.
Macromolecule complex for advanced optoelectronic devices
Authors: Mizoguchi Katsuhiro 
Published: March 2011

AbstractThis paper describes reviews about characterizations of optical and electronic (opto‐electronic) organic materials including macromolecule complex, and their applications for advanced key devices used for computers and communications technologies. On the basis of the author's recent investigations, discussions are made on organic electroluminescent thin film materials for emissive display devices, polymer dispersed liquid‐crystal materials for passive display devices, organic photoconductive materials for electrophotographic printer devices, and highly electroconductive polymers for solid tantalum capacitors. Finally, the technical issues and development prospects for the opto‐electronic organic materials in the 21st century are suggested.
Brownian dynamics of polymeric chain in strong external field
Authors: Neelov Iqor M. , Clarke Julian H. R. 
Published: March 2011

AbstractThe cooperativity of conformational transitions in strained linear polymer chain was investigated by the method of Brownian dynamics. Deformation of a chain consisting of N=32 and 64 bonds was created by strong external field of dipole type. Correlations are discussed in terms of hazard‐plot analysis.
Evaluation of the tension on dna‐segments in the lakes‐straits model
Authors: Loomans Dirk , Blumen Alexander 
Published: March 2011

AbstractWe consider DNA gel electrophoresis in the framework of the lakes‐straits model, proposed by Zimm in Phys. Rev. Lett. 61, 2965 (1988) and J. Chem. Phys. 94, 2187 (1889). Here we evaluate the tension on a Gaussian chain‐fragment confined in a lake, by accounting for its variable length. Through numerical simulations we find that the precise form of the tension is very important for the calculation of the absolute value of the mobility of the chain and that it is of minor importance for establishing the frequency‐dependence of the mobility.
Monte carlo simulation of many‐arm star polymers
Authors: Ohno Kaoru 
Published: March 2011

AbstractThe statistics of many‐arm star polymers in dilute solution is studied by means of the enrichment algorithm [K. Ohno and K. Binder, J. Stat. Phys. 64, 781 (1991)] using a Monte Carlo simulation technique. In this study, typically 50,000 samples of star polymers with 12–32 arms each of which has 50 bonds are generated. The results for the configuration‐number exponent γ(f) are γ(12) = ‐3.4 ± 0.3, γ(18) = ‐8.9 ± 0.2 and γ(32) = ‐29 ± 2.
Influence of microscopic non‐affinity and functionality on the deformation of polymeric networks
Authors: Glatting Gerhard , Winkler Roland G. , Reineker Peter 
Published: March 2011

AbstractA non‐affine model for the description of the stress‐strain behavior of polymer networks is introduced. We assume that the network consists of a gas of phantom chains. The deformation of the chains is taken into account by macroscopic constraints, where the macroscopic deformation is affine and the microscopic one non‐affine. In contrast to existing models, the number of parameters is reduced; nevertheless the main experimental features are reproduced.
Kinetics of network formation by end‐linking: A monte carlo study
Authors: Trautenberg Hans Ludwig , Sommer Jens‐Uwe , Göritz Dietmar 
Published: March 2011

AbstractEnd‐linked tetrafunctional model networks were simulated using the bond‐fluctuation algorithm. The kinetics of network formation was studied and compared with the solution of the rate equation for a four‐step process. A crossover from diffusion‐controlled to reaction‐controlled time behavior depending on the reaction speed was observed. For a reaction probability of 10−3 per movement of an unreacted chain end and a cross‐linker into nearest neighbor position, the rate equation gives a satisfactory description of the kinetics of the reaction.The evolution of the largest cluster as well as local imperfections of the network were considered in detail. The evolution of the cyclic rank differs from the model of Queslel and Mark.The mobility of cross‐links of different functionality was measured.
Polymers on anisotropic lattices
Authors: Stilck Jürgen F. 
Published: March 2011

AbstractThe study of the thermodynamic behavior of polymers on anisotropic Bethe lattices shows a phase diagram for the fourcoordinated lattice which is different from the ones for lattices with larger coordination number. Two distinct polymerized phases appear, one of them having the density of sites incorporated into chains equal to one. The solution of the model on the anisotropic q=4 Husimi lattice leads to similar results. Finally, preliminary phenomenological renormalization group calculations, using the solution of the model on strips of finite widths via transfer matrix calculations, are consistent with a similar phase diagram for the model on the square lattice.
Onsager chains: Semi‐flexible polymers revisited
Authors: Mulder Bela 
Published: March 2011

AbstractUsing a density functional approach we derive the equations describing the equilibrium orientational distribution of a system of chains composed of elongated segments that interact with segments located on other chains through excluded volume interactions and with neighbouring segments of the same chain through a potential that determines the chain flexibility. We analytically determine the limit of stability of the low density isotropic phase as a function of the number of segments and the chain stiffness. The approach turns out to be formally equivalent to a recently proposed mean‐field theory by Petschek and Terentjev. Comparison with the Khoklov‐Semenov theory shows that the latter is based on an additional assumption that is not valid in an orientationally ordered phase.
Configuration‐dependent properties of polyoxyethylene chains in the third‐order interaction approximation
Authors: Linxi Zhang , Tao Jin , Jianmin Xu 
Published: March 2011

AbstractConformational energies of polyoxyethylene chains in the third‐order interaction approximation are calculated using a semiempirical potential energy function in the usual manner. Configuration‐dependent properties of POE in the third‐order are also calculated, and more close to the experimental data.
Free energies and phase equilibria of chain molecules
Authors: Smit Berend , Karaborni Sami , Ilja Siepmann J. 
Published: March 2011

AbstractIn this Article, a review is presented of recent developments in Monte Carlo simulations of chain molecules. The Rosenbluth chain insertion technique is used to calculate the free energy of the chain molecules. Furthermore, this insertion method is used to generate biased Monte Carlo moves. It is shown that this bias can be removed by adjusting the acceptance rules such that configurations are generated with their correct Boltzmann weight. This configurational‐bias Monte Carlo method can be combined with the Gibbs‐ensemble technique which results in an efficient method to simulate phase equilibria of chain molecules.
A model for isotropic, nematic, and columnar ordering in a self‐assembling system ‐ comparison with the phase behavior of 2,3,6,7,10,11‐hexa‐(1,4,7‐trioxaoctyl)‐triphenylene in water
Authors: Hentschke Reinhard , Edwards Patrick J. B. , Boden Neville , Bushby Richard J. 
Published: March 2011

AbstractMany amphiphilic molecules in aqueous solution spontaneously self‐assemble into labile anisotropic aggregates. At large enough concentration, this shape anisotropy may lead to complex liquid‐crystalline mesophases. Here we compare the results of a recent excluded volume model for reversible assembling flexible linear aggregates to a corresponding experimental amphiphilic system, 2,3,6,7,10,11‐hexa‐(1,4,7‐trioxaoctyl)‐triphenylene, in water. Our comparison emphasizes the importance of including aggregate flexibility into theories of micellar assembly.
Amorphous fluoropolymers ‐ a new generation of products
Authors: Korinek P. M. 
Published: March 2011

AbstractPoly(tetrafluoroethylene) (PTFE) already known since 50 years, Is a unique material among plastics due to its chemical inertness, heat resistance, electrical insulation properties and low coefficient of friction. Its high melt viscosity needs special ways of processing. That fact led to the development of melt‐processible fluoropolymers such as Perfluoroethylene‐propylene (FEP) and Perfluoroalkoxy (PFA). Now we have a third generation which is an amorphous fluorpolymer made by copolymerizing tetrafluoroethylene with 2,2‐bis (trifluoromethyl) ‐ 4,5 ‐ difluoro ‐1,3 ‐ dioxole. The bulky cyclic structure prevents the normal crystallisation as with PTFE polymers. The amorphous fluoropolymers have high clarity and dissolve in selected solvents. Having C‐F, C‐C and C‐O bonds the well known properties as high temperature and chemical resistance are retained. Dielectric constant is in the range 1.83 ‐ 1.93 up to 10.00 MHz the lowest of any plastic material. Optical properties are also very special. Refractive index is very low, in the range 1.29 ‐ 1.32. Transmission is high from UV to IR and the polymer is not photo‐degraded. The unique electrical and optical properties, coupled with high chemical and thermal stability, plus the ability to work from solution offers a powerful tool for those working on the frontiers of technology.
Anionic polymerization of hexafluoro‐1,3‐butadiene and characterization of the polymer
Authors: Narita Tadashi 
Published: March 2011

AbstractThe present review describes the anionic polymerization of hexafluoro‐1,3 ‐butadiene (HFBD) and the characterization of the polymer. HFBD which is hardly polymerized under radical polymerization conditions yielded the polymer with cesium and rubidium compounds as initiators in moderate conditions. X‐ray photoelectron spectra and Raman spectra showed the structure of the polymer was similar to that of poly(hexafluoro‐2‐butyne). The polymerization mechanism, an addition reaction of the propagating anion to the 2‐carbon of HFBD followed by isomerization of the propagating end group to yield the polyene structure, is proposed from the results of the investigation of initiation reaction and the structure of the polymers. Poly(HFBD) shows higher thermostability than poly(tetrafluoroethylene) in spite of bearing functional ‐CC‐groups in the polymer main chain.
Perfluorinated and partially fluorinated organic compounds. Preparation, characterization and application
Authors: Meinert H. 
Published: March 2011

AbstractElectrochemical fluorination (ECF) of various heterocyclic compounds has been investigated. α,ω‐Dimorpholinoalkanes of different chain length (n = 1‐6) and of morpholinocyclohexene gave the perfluoro derivatives in yields up to 45%. The crystal and molecular structures of the perfluorinated compounds are presented.The mechanism of ECF for these compounds is discussed on the basis of a steric model. Perfluorocarbon emulsions of second generation were prepared by means of F‐dimorpholines and F‐cyclohexylmorpholine, acting both as oxygen carriers and as interfacial active compounds (IFACs). The stabilizing effect of these IFACs is interpreted. Semifluorinated alkanes, RfRh, are chemically inert and non‐toxic. They are useful for blood substitutes in two ways: as co‐surfactants to stabilize emulsions with perfluorocarbons and as oxygen carriers instead of perfluorocarbons. The high density of perfluorocarbons cause problems in some field of application in medicine. Therefore symmetrical diethers of the type RF(CH2)mO(CH2)nO(CH2)mRF were synthesized. These are inert and biocompatible compounds. Diethers with long RF‐tail and long hydrocarbon spacer are ideal solubilizers for perfluorocarbons with hydrocarbons and vice versa. The diethers with short hydrocarbon spacer and long RF‐tail can be applied in biological systems, because they are not soluble in lipid tissues. Perfluorocarbons (e. g. F‐decalin, F‐octane) are used as medical tools in ophthalmology, their purity is essential. Not totally fluorinated compounds (1 H‐perfluoroalkanes, α,ω‐dihydrogenoperfluoroalkanes) are characterized and discussed. 1H‐perfluoroalkane is also formed by nucleophilic attack on perfluoroalkyl halide.
New pH sensitive network: Combination of an amphiphilic degradable polyester with a β‐cyclodextrin copolymer
Authors: Moine Laurence , Cammas Sandrine , Amiel Catherine , Renard Estelle , Sébille Bernard , Guérin Philippe 
Published: March 2011

AbstractA novel hydrophobic monomer, ethyladamantyl malolactonate, has been synthesized and copolymerized with benzyl malolactonate by anionic ring‐opening polymerization. The ratio of adamantyl monomer varied from 0 to 100 mol%. Deprotection of benzyl groups leads to a water soluble copolyester with carboxylic acid lateral functions which give a polyelectrolyte character to the corresponding polymers. The mixture of a copolyester containing 10% of adamantyl groups and a β‐cyclodextrin/epichlorohydrin copolymer in aqueous solution leads to a new pH‐dependant associating system. The solution behavior of this system was studied by viscosimetry as a function of pH, concentration and ratio of both copolymers. At the initial solution pH (pH=2), the copolyester adopts a coiled structure as a result of hydrophobic interactions between the pendant adamantyl groups. Consequently, no network formation is observed as shown by a very low viscosity. As the pH increase, the viscosity of the medium increases and reaches a maximum at pH=5. At this pH, the copolyester expands because of electrostatic repulsions between the carboxylate pendant functions. Consequently, the adamantyl groups are accessible and can be encapsulated into the β‐cyclodextrin cavities resulting in a significant increase of the viscosity.
Synthesis and controlled photo‐ and biodegradabilities of poly[(hydroxybutyrate ‐Co‐hydroxyvalerate)‐G‐styrene]
Authors: Park Jin , Choi Won‐Moon , Ha Chang‐Sik , Kim Won‐Ho , Cho Won‐Jei 
Published: March 2011

AbstractThe graft copolymer, P(HBV‐g‐St), was synthesized by graft polymerization of styrene (St) onto poly(3‐hydroxybutyrate‐co‐3‐hydroxy valerate) [PHBV] under nitrogen atmosphere using benzoyl peroxide (BPO). The structure of poly[(hydroxybutyrate‐co‐hydroxyvalerate)‐g‐styrene] [P(HBV‐g‐St)] was identified by FT‐K, 1H‐NMR, and 13C‐NMR spectra. The effects of weight ratio of St to PHBV in feed, initiator concentration, reaction time and reaction temperature on the grafting ratio and grafting efficiency were investigated. The thermal decomposition temperature of P(HBV‐g‐St) was 273°C. The tensile strengths of P(HBV‐g‐St) before and after photo‐ or biodegradation were also measured. The photodegradability of P(HBV‐g‐St) was better than that of PHBV. The film surface of P(HBV‐g‐St) treated with Aspergillus nigger showed extensive grooves and pits as compared with the untreated P(HBV‐g‐St). It was found that the photo‐ and biodegradation rates of P(HBV‐g‐St) and tensile strength of P(HBV‐g‐St) can be “controlled” by changing the weight ratio of St to PHBV in feed.
Morphologies and enzymatic degradability of melt‐crystallized poly(3‐hydroxybutyric acid‐Co‐6‐hydroxyhexanoic acid)
Authors: Abe Hideki , Aoki Hiromichi , Doi Yoshiharu 
Published: March 2011

AbstractThe films of poly[(R)‐3‐hydroxybutyric acid‐co‐10mol% 6‐hydroxy‐hexanoic acid] (P[(R)‐3HB‐co‐6HH]) were prepared by melt‐crystallized method at various crystallization temperatures. The morphologies and properties of melt‐crystallized films were characterized by means of x‐ray diffraction, differential scanning calorimetry, optical microscopy, and scanning electron microscopy. All of the melt‐crystallized films showed the banded spherulite morphology. The enzymatic degradation of melt‐crystallized films was carried out at 37 °C in an aqueous solution (pH 7.4) of PHB depolymerase from Alcaligenes faecalis. The rate of enzymatic erosion was strongly dependent on the crystallinity of films, and the highest rate was as large as 2.15 mg·h−1·cm−2. After enzymatic degradation, the banded morphology of P[(R)‐3HB‐co‐6HH] spherulites was visible, suggesting that PHB depolymerase predominantly hydrolyzes polymer chains on the edges of crystalline lamellar stacks.
Synthesis and structures of cooligo(lactone) macromonomers
Authors: Gopp Udo , Sandner Barbara , Schöch Martin , Schlothauer Klaus , Pasch Harald , Ghahary Reza 
Published: March 2011

AbstractCooligo(lactone) macromonomers were prepared by cooligomerisation of (S,S)‐3,6‐dimethyl‐1,4‐dioxane‐2,5‐dione (L‐lactide), 1‐oxacyclohexane‐2‐one (δ‐valerolactone) or 1‐oxacycloheptane‐2‐one (ε‐caprolactone), initiated by 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxypropoxy)phenyl]‐propane (BisGMA). Two different reaction ways were used for the synthesis: parallel reaction and step reaction of lactones and L‐lactide. The macromonomers were characterised by differential scanning calorimetry (DSC), size exclusion chromatography (SEC), 1H‐ and 13C‐NMR spectroscopy and MALDI‐TOF mass spectrometry. Cooligo(lactone) macromonomers prepared by parallel and by step reaction show different molecular structures resulting in different properties. Their glass transition temperatures depend on the molar ratio of lactide and lactone as well as on the degree of oligomerisation. Macromonomers with high amounts of L‐lactide units are partially crystalline.
Thermal properties of polyurethanes derived from molasses before and after biodegradation
Authors: Hatakeyama Tatsuko , Tokashiki Tadaski , Hatakeyama Hyoe 
Published: March 2011

AbstractPolyurethane (PU) foams derived from molasses were placed in soil for various periods from 3 to 12 months. Thermal properties of PU's before and after biodegradation were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). Glass transition of PU's after 3 month's degradation was separated into two stages indicating that molecular chains of the original and decomposed portions move independently. Based on variation of glass transition temperature (Tg), heat capacity difference at Tg (δCp), thermal degradation temperature and mass loss, the degradation mechanism of PU was established.
Biodegradation of polycaprolactone in plant treatment active sludge
Authors: Rutkowska Maria , Dereszewska Alina , Jastrzȩbska Mariola , Janik Helena 
Published: March 2011

AbstractThe object of this study was the degradation of polycaprolactone films in a living composting environment with plant treatment active sludge. The incubation of polymer samples took place in the compost for a period up to 3 months. There are presented the characteristic parameters of plant treatment active sludge: temperature, pH, dry mass and activity of dehydrogenesis and their influence on degradation of polycaprolactone is discussed. The changes of weight, tensile strength, microhardness and morphology during experiment were tested. Enzymatic activity is resulted in surface erosion. Microscopical observations show deterioration of polycaprolactone surface. Hydrolysis (“bulk process”) is also contributed (onset of weight loss). The decreasing of weight and mechanical properties are observed after each period of incubation. The increase in the microhardness during first period of biodegradation can be directly proportional to the increase in crystallinity, because amorphous regions are degraded first what is confirmed by microscopical observation. The complete degradation of polycaprolactone in compost with plant treatment active sludge in living environment takes place after short period of time (3 month).
Ring‐opening polymerization of 1,4,8‐trioxaspiro‐[4.6]‐9‐undecanone: A route to novel molecular architectures for biodegradable aliphatic polyesters
Authors: Tian Dong , Dubois Philippe , Jérǒme Robert 
Published: March 2011

AbstractThe ring‐opening polymerization of 1,4,8‐trioxaspiro‐[4.6]‐9‐undecanone (TOSUO) initiated by aluminum isopropoxide, Al(OiPr)3, is typically “living” and allows random and block copolyesters of predictable molecular weight and composition to be prepared. Deacetalization of the polyester chains is complete, and reduction of the accordingly formed ketone groups into hydroxyl groups as well. No chain scission is observed when these two derivatization reactions are carried out. The potential of these novel functional aliphatic polyesters has been discussed as drug colloidal vectors and macroinitiators for the synthesis of biodegradable and biocompatible comb, graft and even hyperbranched polymers.
Acid‐catalyzed copolymerization of aspartic acid with ω‐amino acid. ‐Biodegradability and Ca2+ chelating ability of poly(aspartic acid ‐Co‐ ω‐amino acid)‐
Authors: Shibata Minako , Kusuno Atsushi , Kakuchi Toyoji , Nakato Takeshi , Yoshikawa Masako , Tomida Masayuki 
Published: March 2011

AbstractThe polycondensation of L‐aspartic acid (1) with various ω‐amino acids (2) using phosphoric acid catalyst produced poly(succinimide‐co‐ω‐amino acid)s (3), which was followed by alkali hydrolysis to poly(aspartic acid‐co‐ω‐amino acid) (4). The Ca2+ chelating abilities of 4 depended on the content of comonomer unit in the copolymer and on the kind of amino acids. For the copolymer using 11‐aminoundecanoic acid (2d) as a comonomer, the Ca2+ chelating ability was higher than that of poly(sodium acrylate). For poly(aspartic acid‐co‐6‐aminocaproic acid) (4c), there was a tendency to increase according to the increase of 6‐aminocaproic acid (2c) unit in the copolymer. The biodegradability of the copolymer in the case of 2c as a comonomer, evaluated by TOC measurement, was 63%, which was the highest degradability among the copolymers having different methylen length. The biodegradability of 4c decreased with increasing the 2c unit in 4c.