bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water sorption in butyl acrylate zwitterionomers of the ammoniopropanesulfonate and ammonioethoxydicyanoethenolate type
Authors: Galin Monique , Galin Jean Claude 
Published: April 2003

AbstractWater sorption by amorphous statistical butyl acrylate (A unit) zwitterionomers bearing ammoniopropanesulfonate (B unit, N+(CH2)3SO, μ = 24.0 D) or ammonioethoxydicyanoethenolate (B′ unit, N+(CH2)2OCOC−(CN)2, μ = 25.9 D) dipolar functional groups was studied at 23°C over a broad range of water activity (0.22 < a < 0.93). For a < 0.65, the sorption isotherms may be analyzed according to the BET equation for a multilayer process characterized by a number of site‐bound water molecules per dipolar unit, independent of copolymer composition and close to that measured on the corresponding zwitterionic homopolymers: nm ≈ 2.0 and 0.7 for AB and AB′, respectively. The initial kinetics of the diffusion process may be described according to a Fickian model up to the saturation of the first solvation layer capacity, with a typical increase of the diffusion coefficient for the AB′ copolymers of strongly reduced waterzwitterion interactions. In spite of the complex heterogeneous morphology of these zwitterionomers, of its continuous evolution and of the change of physical state of the hard domains from glassy to viscoelastic upon hydration, the water sorption process appears rather simple: it is essentially monitored by the overall content and the chemical structure of the dipolar units in the copolymer chains.
Copolymerization of γ‐butyrolactone and β‐butyrolactone
Authors: Lee Chan Woo , Urakawa Ryuichi , Kimura Yoshiharu 
Published: April 2003

AbstractThe copolymerization of a 4‐membered β‐butyrolactone (βBL) and a thermodynamically stable 5‐membered γ‐butyrolactone (γBL) proceeds in the bulk state with BF3 · OEt2 as a catalyst at room temperature to give poly[(3‐hydroxybutyrate)‐co‐(4‐hydroxybutyrate)] (P(3HB‐co‐4HB)) whose structure is identical with that of a polyester formed by microorganisms. The copolymer structure was confirmed by 1H and 13C NMR spectroscopy. The monomer reactivity ratios were r(γBL) = 0.48 and r(βBL) = 0.58, respectively, and the unit composition of 4HB increases to 56% at high γBL to βBL ratio in the feed. End group analysis of the copolymer suggests the presence of a hydroxyl group and a carboxyl group at the ends of each polymer molecule. It was postulated that the monomers activated by BF3 react with the hydroxy group derived from the water contaminant in the monomers.
Aromatic polymers obtained by precipitation polycondensation, 2. Synthesis of poly(ether ketone ether ketone ketone) (PEKEKK)
Authors: Zolotukhin Mikhail G. , Rueda Daniel R. , Calleja Francisco J. Baltá , Bruix Marta , Cagiao Maria E. , Bulai Anna , Gileva Natalia G. 
Published: April 2003

AbstractA high molecular weight, linear aromatic poly(ether ketone ether ketone ketone) (PEKEKK) has been synthesized by electrophilic Friedel‐Crafts acylation condensation of 1,4‐diphenoxybenzophenone with terephthaloyl chloride. The syntheses were performed as precipitation polycondensations, and the polyketones were obtained in particle form. The viscosity (molecular weight), shape and size of these particles were found to be strongly dependent on the reaction conditions. For low monomer concentration, highly ordered needle‐like particles were also obtained. The chemical structure of the polymers obtained was confirmed by 1H and 13C NMR spectroscopy, and para‐substitution in aryl fragments of the main chain was identified. Analysis of the expanded 1H NMR spectra for the ring proton resonances reveals defect meta‐ and ortho‐structures. The amount and isomer ratio of these defect structures depend on the monomer concentration used.
Polymerization of lactams, 88. Copolymers poly(ϵ‐caprolactam)‐block‐polybutadiene prepared by anionic polymerization, part III. Model polymerizations initiated with potassium salt of ϵ‐caprolactam and accelerated with isocyanates and their derivatives
Authors: Sobotík Roman , Šrubař Radim , Roda Jan 
Published: April 2003

AbstractAnionic polymerization of ϵ‐caprolactam was initiated with the potassium salt of ϵ‐caprolactam and accelerated with phenyl isocyanate, toluylene diisocyanate, 4,4′‐diphenylmethane diisocyanate, some derivatives of these isocyanates (urethanes, ureas, and allophanates), or combinations of phenyl isocyanate with its derivatives at 150°C. The effect of individual structures on the polymerization kinetics and their contribution to the preparation of block copolymers of ϵ‐caprolactam with hydroxy‐terminated prepolymers, in‐situ functionalized with diisocyanates, are discussed on the basis of a detailed analysis of time functions of polymer yield and degree of polymerization.
Biorecognition of sugar containing N‐(2‐hydroxypropyl)methacrylamide copolymers by immobilized lectin
Authors: Rathi Ramesh C. , Kopečková Pavla , Kopeček Jindřich 
Published: April 2003

AbstractThe interactions of sugar containing N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymers with Tetragonolobus purpureas (Lotus tetragonolobus) lectin immobilized on 4% beaded agarose have been studied. HPMA copolymers containing side‐chains terminating in N‐acylated amino sugars, namely, fucosylamine, galactosamine, glucosamine and mannosamine were synthesized and their biorecognition evaluated. As expected, only fucosylamine containing HPMA copolymers showed specific binding to the lectin. The dissociation constants (Kd) for HPMA copolymers were determined by frontal affinity chromatography. The binding constant was dependent on the amount of fucosylamine residues per macromolecule. An increase in fucosylamine content from 9,9 to 33,2 mol‐% resulted in a decrease of Kd by one order of magnitude. Incorporation of hydrophobic side‐chains such as glycylglycyl‐5‐[4‐(2‐aminoethylcarbamoyl)phenylazo]salicylic acid, 1′‐(β‐hydroxyethyl)‐3′,3′‐dimethyl‐6‐nitrospiro(2H‐1‐benzopyran‐2,2′‐indoline) (SP), or 1′‐(β‐glycylglycyloxyethyl)‐3′,3′‐dimethyl‐6‐nitrospiro(2H‐1‐benzopyran‐2,2′‐indoline) (GG‐SP) into the copolymers increased the non‐specific binding to the lectin. Photoinduced isomerization of bound spiropyrans to merocyanines was accompanied by changes in the conformation and biorecognition of HPMA copolymers. The results obtained demonstrated the impact of the structure and solution conformation of sugar containing HPMA copolymers on their biorecognition.
Propene polymerization with MgCl2‐supported catalysts: effects of using a diether as external donor
Authors: Chadwick John C. , Morini Giampiero , Balbontin Giulio , Mingozzi Ines , Albizzati Enrico , Sudmeijer Olof 
Published: April 2003

Abstract13C NMR analysis of poly(propylene) fractions of different tacticity, obtained using a catalyst system of type MgCl2/TiCl4/diisobutyl phthalate – AlEt3 – diether, has provided further evidence that the active species in this system are similar to those in which the ether is used as “internal” rather than “external” donor. Chain‐end analysis of relatively low molecular weight polymer fractions indicated, for polymers of similar molecular weight, similar proportions of butyl‐terminated chain‐ends, indicative of chain transfer with hydrogen following regioirregular (2,1‐) insertion. The relatively high hydrogen response of diether‐containing catalyst systems can therefore be largely ascribed to this phenomenon, irrespective of whether the diether is used as internal or external donor. At relatively low hydrogen concentrations, chain transfer to hydrogen takes place predominantly after the occasional secondary insertion, while the additional presence of vinylidene chain‐ends in certain xylene‐soluble fractions indicates that chain transfer via β‐H transfer takes place mainly after primary insertion.
Kinetic study of isospecific active sites formed by various alkylaluminiums on MgCl2‐supported Ziegler catalyst at the initial stage of propene polymerization
Authors: Mori Hideharu , Iguchi Hiromitsu , Hasebe Kouichi , Terano Minoru 
Published: April 2003

AbstractThe effect of various kinds of alkylaluminium on the kinetic parameters of the initial stage of propene polymerization with MgCl2‐supported Ziegler catalyst was studied by the stopped‐flow polymerization method. The active sites concentration ([C*]) decreased drastically with the increase of bulkiness of the alkyl group of the aluminium compound, while the change of the propagation rate constant (kp) was rather small and proportional to the meso pentad fraction of the resulting polypropene. The kinetic parameters, kp(insol) and [C*(insol)], were calculated from the yield and number‐average molecular weight of the boiling heptane insoluble fraction. The values of kp (insol) were almost constant, while those of kp depended on the ratio [C*(insol)]/[C*(total)]. The results obtained in this study suggest that isospecific active sites produced by various alkylaluminiums are essentially the same, but the amounts of the active sites formed with a variety of alkylaluminiums are different.
Single crystals of syndiotactic poly[propene‐co‐(1‐octene)] and syndiotactic polypropene crystallized in bulk
Authors: Thomann Ralf , Kressler Jörg , Mülhaupt Rolf 
Published: April 2003

AbstractSingle crystals grown in bulk samples of a syndiotactic random copolymer of propene and 1‐octene with 4 wt.‐% 1‐octene are compared with single crystals of syndiotactic polypropene homopolymer. The random copolymer during isothermal crystallization at low supercoolings forms rectangular single crystals similar to syndiotactic polypropene. The single crystals of the random copolymer do not exhibit transverse cracks in contrast to neat syndiotactic polypropene. Both polymers have nearly the same linear thermal expansion coefficients along their crystallographic a‐ and b‐axis, calculated from temperature‐dependent wide‐angle X‐ray scattering (WAXS) measurements. Therefore, the absence of transverse cracks in single crystals of the random copolymer can only be explained by the relatively high disorder of the crystallite surface caused by the exclusion of 1‐octene segments which leads to a more isotropic thermal expansion coefficient in this region.
Polymers from multifunctional isocyanates, 13. Functional polymers from N‐substituted poly(maleimide‐alt‐isopropenyl isocyanate)s
Authors: Mormann Werner , Grimm Axel 
Published: April 2003

AbstractAlternating copolymers from isopropenyl isocyanate and N‐substituted maleimides (N‐phenyl, N‐tetradecyl‐ and N‐octadecylmaleimide) were synthesized for the first time. The reactive copolymers with regular structure have an isocyanate group in the constitutional repeating unit which allows modification and functionalization in a polymer analogous reaction. Functionalization has been demonstrated with examples of amphiphilic copolymers having the hydrophobic and the hydrophilic chain attached to the polymer backbone in a regular alternating fashion. A second example is an alternating copolymer with an NLO‐chromophore attached to the polymer.
Synthesis of 3‐amino‐ribofuranans having 1,5‐α and ‐β structures by selective ring‐opening polymerization of a 1,4‐anhydro‐3‐azido‐3‐deoxy‐α‐D‐ribopyranose derivative
Authors: Kang Byoung Won , Hattori Kazuyuki , Yoshida Takashi , Hirai Makoto , Chio Yoon Soung , Uryu Toshiyuki 
Published: April 2003

AbstractRing‐opening polymerization of a new anhydro ribose‐type monomer, 1,4‐anhydro‐3‐azido‐3‐deoxy‐2‐O‐tert‐butyldimethylsilyl‐α‐D‐ribopyranose (A3ASR), was investigated. The monomer was synthesized from 1,4‐anhyro‐α‐D‐xylopyranose by three steps comprising Walden inversion at the C3 position into ribose configuration. Ring‐opening polymerization of A3ASR by Lewis acid catalysts such as boron trifluoride etherate and stannic chloride gave a stereoregular 3‐azido‐3‐deoxy‐2‐O‐tert‐butyldimethylsilyl‐(1→5)‐α‐D‐ribofuranan having specific rotations of +246 ∼ +271 deg · dm−1 · g−1 · cm3 and number‐average molecular weights of 18,7 × 103 ∼ 25,1 × 103. When the polymerization was carried out by antimony pentachloride at 0°C, the resulting polymer exhibited a negative specific rotation of −6 deg · dm−1 · g−1 · cm3 and the C1 absorption in the 13C NMR spectrum shifted downfield to 107,5 ppm, suggesting that the polymer might consist of 1,5‐β furanosidic unit. The reduction of the azido group of the 1,5‐α and 1,5‐β furanosidic polymers into amino group and subsequent desilylation gave 3‐amino‐3‐deoxy‐(1→5)‐α‐ and ‐β‐D‐ribofuranans, respectively. In addition, copolymerization of A3ASR with 1,4‐anhydro‐2,3‐di‐O‐tert‐butyldimethylsilyl‐α‐D‐ribopyranose (ADSR) in various feeds was performed by boron trifluoride etherate as catalyst to give copolymers with different monomeric components. The structural analysis of the homopolymers and copolymers was examined by means of 1H and 13C NMR spectroscopies, IR spectroscopy, and optical rotation.
Synthesis and characterization of random and regular L‐lysine‐based polyamides
Authors: Gachard Isabelle , Coutin Bernard , Sekiguchi Hikaru 
Published: April 2003

AbstractThis paper deals with the synthesis of polyamides based on the natural diamine, L‐lysine, on the one hand, and diacids, adipic or glutaric, on the other hand. They were obtained by polycondensation of active diesters, pentachlorophenyl and pentafluorophenyl esters. L‐Lysine being non‐symmetrical, aregic (random) and syndioregic (“head‐to‐head, tail‐to‐tail”) poly(adipoyl‐L‐lysine)s and poly(glutaroyl‐L‐lysine)s were obtained with molecular weights higher than 15000; isoregic (“head‐to‐tail”) poly(adipoyl‐L‐lysine)s and poly(glutaroyl‐L‐lysine)s were prepared with lower molecular weights.
A novel side‐chain liquid crystal polymer of 5‐substituted cis‐cyclooctene via ring‐opening metathesis polymerization
Authors: Winkler Berthold , Rehab Ahmed , Ungerank Markus , Stelzer Franz 
Published: April 2003

AbstractIn this communication, we report the synthesis and ring‐opening metathesis polymerisation (ROMP) of a 5‐substituted cyclooctene‐derivative, (±)‐cis‐[11‐(4′‐cyanobiphenyl‐4‐yloxy)undecyl]cyclooct‐4‐enecarboxylate. A highly active molybdenum‐carbene was used as initiator. The prepared polymer is liquid crystalline and shows a nematic phase between −5 and 53°C.
Crystallization behavior of blends of high‐density polyethylene with novel linear low‐density polyethylene
Authors: Zhao Yong , Liu Shengsheng , Yang Decai 
Published: April 2003

AbstractBlends of high‐density polyethylene (HDPE) with novel linear low‐density polyethylene (LLDPE) samples in the whole range of compositions were investigated by means of differential scanning calorimetry (DSC), small‐angle X‐ray scattering (SAXS) and wide‐angle X‐ray diffraction (WAXD). The LLDPEs are ethylene/octene‐1 copolymers prepared with a single‐site catalyst, with a narrower distribution of branches compared to Ziegler‐Natta type polymers. It was found that cocrystallization or separate crystallization in the blends profoundly depends on the content of branches in the LLDPE, while the critical branch content of the novel LLDPE for separate crystallization is much lower than that of commercial LLDPE (prepared with Ziegler‐Natta catalysts). This implies that the miscibility of linear and branched polyethylene is also affected by the distribution of branches. The marked expansion of the unit cell in cocrystals, which are formed by HDPE with the novel LLDPE, indicates that the branches are included in the crystal lattice during the cocrystallization process. The result is very helpful to understand the phenomenon that the unit cell dimensions of commercial branched polyethylene are larger than those of linear polyethylene.
A systematic spectroelectrochemical investigation of alkyl‐substituted anilines and their polymers
Authors: Probst Matthias , Holze Rudolf 
Published: April 2003

AbstractVarious aniline derivatives carrying one or two alkyl substituents in various positions (alkylanilines, toluidines and xylidines) were polymerized electrochemically. The obtained conducting polymers were characterized by cyclic voltammetry, in situ infrared spectroscopy and in situ conductivity measurements. Differences in the electrochemical properties of the investigated monomers and polymers are polymers are explained on the basis of steric and electronic effects of the substituents. These conclusions are supported by data of vibrational spectroscopy.
Regioselectivity of the Pd‐catalyzed synthesis of arylenevinylenes and its impact on polymer properties: Model reaction and polyreactions
Authors: Klingelhöfer Stephanie , Schellenberg Carsten , Pommerehne Jörn , Bässler Heinz , Greiner Andreas , Heitz Walter 
Published: April 2003

AbstractThe regioselectivity of Pd‐catalyzed coupling reactions of functionalized benzenes and olefins with respect to the ratio of 1.2‐product/1.1‐product was monitored by model reactions. The coupling of halobenzenes, benzene triflate, and aryldiazonium salts was studied under various reaction conditions. In order to simulate corresponding polyreactions, special focus was on the coupling of ortho‐substituted functionalized benzenes with ethylene or styrene in order to evaluate the input of mono‐ and disubstituted aryl monomers and the choice of the olefin on the regioselectivity of polyreactions. The results of the model reactions were transferred to the polyreactions. The polymers were characterized by NMR, absorption and photoluminescence spectroscopy as well as electroluminescence.
Critically evaluated rate coefficients for free‐radical polymerization, 2.. Propagation rate coefficients for methyl methacrylate
Authors: Beuermann Sabine , Buback Michael , Davis Thomas P. , Gilbert Robert G. , Hutchinson Robin A. , Olaj Oskar Friedrich , Russell Gregory T. , Schweer Johannes , van Herk Alex M. 
Published: April 2003

AbstractPulsed‐laser polymerization (PLP) in conjunction with molar mass distribution (MMD) measurement is the method of choice for determining the propagation rate coefficient kp in free‐radical polymerizations. The authors, members of the IUPAC Working Party on Modeling of kinetics and processes of polymerization, collate results from using PLP‐MMD to determine kp as a function of temperature T for bulk free‐radical polymerization of methyl methacrylate at low conversions and ambient pressure. Despite coming from several different laboratories, the values of kp are in excellent agreement and obey consistency checks. These values are therefore recommended as constituting a benchmark data set, one that is best fitted by

The 95% joint confidence interval for these Arrhenius parameters is also given. In so doing, we describe the most appropriate statistical methods for fitting kp(T) data and then obtaining a joint confidence interval for the fitted Arrhenius parameters. As well, we outline factors which impose slight limitations on the accuracy of the PLP‐MMD technique for determining kp, factors which may apply even when this technique is functioning well. At the same time we discuss how such systematic errors in kp can be minimized.
Free radical polymerisation studies of 4‐substituted styrenes, 1. The reactions of 2‐cyano‐2‐propyl radicals with styrene, 4‐methoxystyrene and 4‐methylstyrene
Authors: Berry Robert William Huxley , Ludlow Andrew John , Mazza Robert John 
Published: April 2003

AbstractOnly a limited amount of work has been previously published concerning the free radical polymerisation of 4‐methoxystyrene and 4‐methylstyrene initiated by 2,2′‐azoisobutyronitrile (2,2′‐azobis(2‐methylpropiononitrile)) (AIBN). The present investigation was, therefore, undertaken to establish whether the substituents have a considerable affect on the reaction of 2‐cyano‐2‐propyl radicals at 60°C, relative to styrene. Rates of polymerisation were determined gravimetrically and rates of initiation were calculated from the radioactivity of the polymer, obtained by labelling AIBN with carbon‐14. Number average molecular weights (Mn) were determined by gel permeation chromatography (GPC). The order of reaction with respect to initiator concentration was found to be 0.50 for styrene and 0.48 for both 4‐methoxystyrene and 4‐methylstyrene, which was attributed to their susceptibility to primary radical termination. Polystyryl radicals were also found to undergo primary radical termination and values for the constant {kprt/(ki·kp)} were determined as 1.37 × 104 mol · s · dm−3 for styrene, 1.47 × 104 mol · s · dm−3 for 4‐methoxystyrene and 1.30 × 104 mol · s · dm−3 for 4‐methylstyrene. The rate of initiation for 4‐methoxystyrene is greater than for styrene, which in turn is greater than for 4‐methylstyrene.
Synthesis and characterization of 1,3,4‐oxadiazole‐containing polyethers from 2,5‐bis(4‐fluorophenyl)‐1,3,4‐oxadiazole and various aromatic diols
Authors: Saegusa Yasuo , Iwasaki Takeshi , Nakamura Shigeo 
Published: April 2003

AbstractSix 1,3,4‐oxadiazole‐containing polyethers with reduced viscosities of 0,65–1,17 dL · g−1 were synthesized by high‐temperature solution polycondensation of an activated difluoride, 2,5‐bis(4‐fluorophenyl)‐1,3,4‐oxadiazole, with aromatic diols possessing a variety of ring structures. The expected chemical structures were confirmed by IR and 1H NMR spectroscopy and elemental analysis. Of all the polymers, two polyethers were highly crystalline and soluble only in limited solvents such as o‐chlorophenol and conc. sulfuric acid. The other polyethers were amorphous and dissolved readily in a variety of organic media including polar aprotic solvents, phenols and chlorinated hydrocarbons. Colorless to slightly yellow‐colored, transparent and tough films could be cast from the N‐methyl‐2‐pyrrolidone or o‐chlorophenol solutions. The mechanical properties were excellent and their tensile strength, elongation at break and tensile moduli were in the ranges of 53–80 MPa, 4–12% and 1,3–2,0 GPa, respectively. The amorphous polyethers had high glass transition temperatures of 195–259°C. All the polyethers were highly thermally and thermooxidatively stable and exhibited no weight loss up to 400°C, with 10% weight loss being recorded at 464–514°C in air.
Syndiotactic polymerization of styrene with cyclopentadienyltribenzyloxytitanium/methylaluminoxane catalyst
Authors: Wu Qing , Ye Zhong , Lin Shangan 
Published: April 2003

AbstractSyndiotactic polystyrene was efficiently prepared in the presence of a homogeneous catalyst composed of (η5‐cyclopentadienyl)tribenzyloxytitanium and methylaluminoxane (MAO) as a cocatalyst. Influences of various polymerization conditions, e.g., [Ti]. [MAO], [St], temperature and the content of retained trimethylaluminium (TMA) in MAO on the catalytic activity, syndiotacticity and molecular weight of the polymer were studied. It was found that the retained TMA plays an important role in the polymerization. Lowering the retained TMA content in MAO decreases the activity of the catalyst remarkably. Addition of external alkylaluminium (TMA or triisobutylaluminium) into the catalyst system with MAO containing low amounts of retained TMA promotes styrene polymerization.
UV‐curable systems containing perfluoropolyether structures: Synthesis and characterisation
Authors: Priola Aldo , Bongiovanni Roberta , Malucelli Giulio , Pollicino Antonino , Tonelli Claudio , Simeone Giovanni 
Published: April 2003

AbstractThe synthesis of new functionalised macromers containing perfluoropolyether structures (PFPE) is reported. They are obtained by reaction of bis‐CH2OH terminated PFPE with isocyanato‐ethyl methacrylate (EIM), giving rise to the formation of perfluoropolyether bisurethane methacrylate (PFEUMA) oligomers. The products are characterised by NMR and FTIR analyses. The thermal behaviour reveals two amorphous phases, corresponding to the fluorinated and the hydrogenated moieties, while a crystalline phase can be present depending on the macromer structure. The functionalised macromers are UV‐cured in the presence of a photoinitiator and the complete disappearance of the double bonds is obtained. The cured films are characterised by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) confirming the presence of a multiphasic structure. Moreover the optical properties and the surface properties of the cured systems are investigated and discussed.