bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poly(germanium thiolate): a new class of organometallic polymers having a germanium‐sulfur bond in the main chain
Authors: Shoda Shin‐Ichiro , Iwata Satoru , Kim Hyun Joon , Hiraishi Masafumi , Kobayashi Shiro 
Published: April 2003

AbstractA novel germanium‐containing copolymer 3 a having a germanium(IV) unit and a trimethylene sulfide unit alternatingly in the main chain was prepared by the combined use of a germylene, 1,3‐bis(trimethylsilyl)‐1,3‐diaza‐2‐germa(II)‐indan (1 a) and thietane (2). The resulting copolymer has a very high molecular weight (M̄w > 106). The usage of a germylene, bis[bis(trimethylsilyl)aminato]germanium(II) (1 b), as a comonomer also gave an alternating copolymer 3 b with high molecular weight in good yields. On the other hand, the reaction of a germylene, bis(N‐trimethylsilyl‐tert‐butylaminato)germanium(II) (c), with thietane afforded a 1 : 1 adduct 4c having a 1‐thia‐2‐germacyclopentane structure without producing an alternating copolymer.
Study on the morphology in composite emulsion particles produced by seed emulsion polymerization
Authors: Liu Zhengping , Liu Fengqi , Liu Zhiqiang , Tang Xinyi 
Published: April 2003

AbstractA series of poly(ethyl acrylate)/polystyrene composite emulsions with different compositions and levels of emulsifier was produced by seed emulsion polymerization. The morphology of the composite particles was inferred from their coalescence ability detected by torsional braid analysis. It was found that the poly(ethyl acrylate) will partially move to the exterior of the particles when using it as a seed, and the increase of surface tension of the particles can enhance this diffusion.
Cationic ring‐opening polymerization of 2‐isopropenyl‐4‐methylene‐1,3‐dioxolane in donative solvents
Authors: Park Jaekyeung , Kihara Nobuhiro , Endo Takeshi 
Published: April 2003

Abstract2‐Isopropenyl‐4‐methylene‐1,3‐dioxolane (1) undergoes cationic polymerization in donative solvents without crosslinking to afford poly(ether‐ketone) 2 having two unitstructures. When solvents having medium donor number (DN = 14,1–17,1), such as acetonitrile, dioxane, ethyl acetate, and propylene carbonate, were used, 2 was obtained in high yields. When solvents having DN (>19,2), such as diethyl ether, DMF, and DMAc, were used, the rate of polymerization decreased considerably, although polymerization proceeded even in the most donative solvent, DMAc (DN = 27,8). The ratio of the unit‐structures was independent of the solvent used. When ethanol was used as the solvent, ethoxyacetone and methacrolein were obtained instead of 2. It was concluded that hard nucleophiles such as ethanol attack at the α′‐position of terminal oxyallyl cation, while soft nucleophiles such as monomer 1 attack at the α‐or γ‐position.
Liquid crystallinity of poly(ester‐imide)s derived from biphenyl‐4,4′‐diol and ω‐amino acids. Studies on low molecular weight model compounds
Authors: Orzeszko Andrzej 
Published: April 2003

AbstractThe liquid crystallinity of poly(ester‐imide)s obtained from biphenyl‐4,4′‐diol, ω‐amino acids and trimellitic anhydride is discussed. Four models 1–4, similar to repeating units I–III, were prepared from biphenyl‐4,4′‐diol or biphenyl‐4‐ol and 6‐phthalimido‐hexanoic acid, 6‐(4‐carboxyphthalimido)hexanoic acid and N‐hexyltrimellitimide. DSC and microscopic studies revealed that only biphenyl groups esterified with two aromatic acids are thermotropic, and those parts of the chain probably induce liquid crystallinity.
Linear non‐conjugated dienes from biomass as termonomers in EPDM synthesis, 3. Conventional versus metallocene catalysis
Authors: Dolatkhani Marc , Cramail Henri , Deffieux Alain 
Published: April 2003

AbstractThe synthesis in the presence of the rac‐EtInd2ZrCl2/MAO catalytic system of new EPDM terpolymers based on linear non‐conjugated dienes issued from biomass, 3,7‐dimethylocta‐1,6‐diene (3,7‐DMO) and 5,7‐dimethylocta‐1,6‐diene (5,7‐DMO), is described. 5,7‐DMO can be readily incorporated in ethylene/propylene (E/P) chains, while 3,7‐DMO does not react in the presence of the metallocene catalyst. The reactivity of these linear dienes is compared with that of 2‐ethylidenebicyclo[2.2.1]hept‐5‐ene (ENB), the preferred termonomer for the industrial synthesis of EPDMs. With the metallocene catalyst, the reactivity of 5,7‐DMO is close to that of ENB, suggesting that 5,7‐DMO is a good candidate for the synthesis of a new EPDM. A comparison with the conventional catalysis based on vanadium systems shows that the advantages of the metallocene catalysis consist in higher catalyst activities and higher incorporation rates of the termonomers in the polymer without any noticeable side reaction. The structural and physico‐chemical characteristics of the various terpolymers, investigated by NMR, SEC and DSC, also underline that the use of metallocenes allows one to prepare EPDM based on linear dienes, with an homogeneous chemical composition and a controlled structure.
Photocleavage mechanism of polyimides having cyclobutane rings
Authors: Ohkita Hideo , Tsuchida Akira , Yamamoto Masahide , Moore James A. , Gamble Donald R. 
Published: April 2003

AbstractThe photocleavage reaction of dimer model compounds of photosensitive polyimides having cyclobutane rings in the main chain was studied. Efficient photocleavage was observed for the dimer models (CBAM2, CBAM4, and CBPM2) which had an electron‐donating aromatic substituent at the electron‐accepting imide group. On the other hand, the cleavage quantum yield was nearly zero for a dimer (CBCM2) which had a cyclohexane substituent instead of the aromatic ring. Solvent polarity effects on the cleavage quantum yield revealed that these dimers gave the largest photocleavage efficiency in medium‐polar solvents. The transient absorption band of the excited triplet of CBPM2 was effectively quenched by oxygen, whereas no oxygen quenching was observed for the cleavage quantum yield. This leads to the conclusion that the cyclobutane ring in the polyimide is photocleaved via the excited singlet intramolecular CT state.
Aspects of hydrogen activation in propene polymerization using MgCl2/TiCl4/diether catalysts
Authors: Chadwick John C. , Morini Giampiero , Albizzati Enrico , Balbontin Giulio , Mingozzi Ines , Cristofori Antonio , Sudmeijer Olof , Van Kessel Gerard M. M. 
Published: April 2003

Abstract13C NMR analysis of the chain‐end distribution of poly(propylenes) prepared using the highly active catalyst system MgCl2/TiCl4/diether—AlEt3 has revealed particularly high proportions of butyl chain‐ends in polymers prepared at relatively low hydrogen pressures. This indicates that the high sensitivity of this type of catalyst to hydrogen, both with respect to catalyst activity and polymer molecular weight, can largely be ascribed to chain transfer following regioirregular (2,1‐) insertion, such an insertion leading to a species having low activity in chain propagation. Isotactic stereoregularity increases with increasing hydrogen pressure, indicating that a stereoirregular insertion may also slow down the chain propagation, again leading to chain transfer and resulting in the conversion of a potential chain defect into an isobutyl chain‐end. Analysis of highly isotactic polymer fractions isolated via temperature rising elution fractionation revealed the presence of both butyl and isobutyl chain‐ends, indicating that even the most highly stereo‐specific sites in MgCl2‐supported catalysts are not totally regiospecific.
Microstructures of emulsified polymer blends
Authors: Adedeji Adeyinka , Jamieson Alex M. , Hudson Steven D. 
Published: April 2003

AbstractMorphologies of solvent‐cast blends of immiscible polymer pairs emulsified with block copolymers have been examined using transmission electron microscopy. The morphology of such blends is controlled by the delicate balance in the swelling of each block copolymer segment by the corresponding compatible homopolymers. By manipulating the relative swelling via changes in molecular weight and enthalpic interactions, a variety of morphologies including macrophase co‐existing with microphase, and microphase alone, with structures ranging from spheres to vesicles, vesicles co‐existing with worm‐like microdomains, and phase‐inverted networks (PIN), are observed. The morphologies of ternary blends of the type A/A‐b‐B/B and A/X‐b‐B/B can be related to the phase behavior observed in the binary A/A‐b‐B and A/X‐b‐B blends.
Kinetic study of the heterogeneous anionic coordinated polymerization of ethylene oxide
Authors: Letourneux Jean‐Pierre , Hamaide Thierry , Spitz Roger , Guyot Alain 
Published: April 2003

AbstractNew heterogeneous catalytic systems for anionic ring opening polymerization of oxygenated heterocycles are obtained by grafting alkylaluminium moieties on porous silica. Adding alcohol in excess causes the formation of aluminium alkoxides and allows a rapid exchange reaction between the grafted active centers and the free alcohols remaining in the solution, so that more polymer molecules than the number of metal atoms used are produced. An interesting feature is the facility to obtain functionalized oligomers because these exchange reactions lead to polymer chains end‐capped by moieties derived from the alcohol molecules. The kinetic behaviour was investigated for different monomer, alcohol and aluminium concentrations. An activation is observed for a well‐defined alcohol concentration range which is interpreted in terms of the enhancement of the nucleophilic reactivity of the oxygen atom of the alkoxide due to the coordination of the free alcohol onto the active centers and the share of the acidic vacancy of the aluminium atom.
Synthèse de l'acide 2‐acrylamido 2‐méthylpropanoïque et copolymérisation avec l'acrylamide
Authors: Camail Michel , Margaillan André , Thuret Sandrine , Vernet Jean‐Louis 
Published: April 2003

AbstractThe synthesis of 2‐acrylamido‐2‐methylpropanoic acid (2A2MPA) was carried out starting from 2‐methylpropanoic acid. Copolymerizations of the 2A2MPA salt (2A2MPANa, monomer A) with acrylamide (AM, monomer B) were investigated using K2S2O8 as initiator. They were terminated before reaching 15% conversion. A range of feed compositions was selected (2A2MPANa increasing from 10 to 100 mol‐%) and the compositions of the copolymers obtained were assessed through 13C NMR. The reactivity ratios for the couple A, B were determined as rA = 0,76 and rB = 1,06. One additional copolymerization was allowed to reach 100% conversion, and the final copolymer showed interesting drag reduction properties.
Interaction of N‐tert‐butylaziridine with π‐electron acceptors, 2. Polymerization initiated by tetracyanoethylene
Authors: Christova Darina Ch. , Velichkova Rumiana S. , Panayotov Ivan M. 
Published: April 2003

AbstractThe interaction of N‐tert‐butylaziridine (TBA) with the strong π‐electron acceptor tetracyanoethylene (TCNE) was investigated, which results in ring‐opening polymerization of the aziridine. Charge‐transfer complex formation between TBA and TCNE was proved by means of UV/VIS spectroscopy and is assumed to be the first stage of the initiation. There is evidence that only linear TBA homopolymers are formed and TCNE is not covalently bound in the polymer chains as comonomer. The acceptor is present in the final products as a stable complex with the nitrogen atoms along the polyaziridine chains.
Synthesis and phase behaviour of new carbazole containing liquid crystal side chain polysiloxanes
Authors: Arnim Volkmar v. , Finkelmann Heino , Dobarro Alicia , Velasco Dolores 
Published: April 2003

AbstractA series of chiral mesogenic side chain polymers containing a carbazole unit have been synthesized and investigated with regard to their liquid crystal (1c) phase behaviour. The carbazole units are linked either via the 2‐position with a 1‐oxycarbonyl‐4‐alkoxylphenyl moiety (end‐on) or via the 9‐position with an alkyl chain (side‐on) to polymethylsiloxane. Only end‐on polymers with long spacers or a ratio bigger one of spacer length and the free lateral alkyl chain length exhibit stable or metastable smectic phases. The side‐on polymers are only isotropic or crystalline.
Polymerization of cyclic monomers, 2. Synthesis and radical polymerization of vinylcyclopropanes
Authors: Zeuner Frank , Moszner Norbert , Rheinberger Volker 
Published: April 2003

AbstractNew 1,1‐disubstituted 2‐vinylcyclopropanes were synthesized by reaction of the corresponding malonyl diesters with trans‐1,4‐dibromo‐2‐butene and of sodium hydride. The structure of the 2‐vinylcyclopropanes could be confirmed by elemental analysis, IR, 1H NMR and 13C NMR spectroscopy. Radical polymerization of the 2‐vinylcyclopropanes in bulk with 2,2′‐azoisobutyronitrile (AIBN) and di‐tert‐butyl peroxide (DtBPO), respectively, gives transparent polymers. In case of the liquid monomers, the polymerization is accompanied by negative volume changes. Spectroscopic investigations show that 2‐vinylcyclopropanes primarily undergo opening of the cyclopropane ring forming an 1,5‐addition polymer.
Thermotropic liquid‐crystalline aromatic‐aliphatic polyimides, 7. Poly(ester‐imide)s based on 3,4:3″,4″‐p‐terphenyldicarboximide
Authors: Sato Moriyuki , Ujiie Seiji , Hirata Tomohiro 
Published: April 2003

AbstractNew thermotropic liquid crystalline semi‐rigid homo‐ and copoly(ester‐imide)s composed of the 3,4:3″,4″‐p‐terphenyldicarboximide and/or the biphenyl unit and flexible aliphatic chains were prepared by polytransesterification using a dihexanol derivative of 3,4:3″,4″‐p‐terphenyldicarboximide and/or a dioxydihexanol of biphenyl as monomers. Differential scanning calorimetry (DSC) measurements, polarizing microscope observations and powder X‐ray analyses at various temperatures indicated that the homopolymer containing the 3,4:3″,4″‐p‐terphenyldicarboximide unit forms a smectic phase and the copolymers a nematic phase. It is suggested that the 3,4:3″,4″‐p‐terphenyldicarboximide unit acts as a good mesogen.
Polyanhydrides, 8. Hydrolytic degradation of aromatic poly(ester‐anhydride)s
Authors: Kricheldorf Hans R. , Jürgens Claas 
Published: April 2003

AbstractThe hydrolytic degradation of three aromatic poly(ester‐anyhdride)s, PEA's, was studied at 25°C in buffer solutions at pH 6 and pH 7 over a period of 16 and 14 months, respectively. Two PEA's (1 and 2a) possessed an ester/anhydride mole ratio of 75 : 25. The loss of weight, the film thickness, elemental analyses, IR spectra, GPC curves and SEM micrographs were recorded. It was found that the degradation of the molecular weights is much faster than the loss of weight and the decrease of the film thickness. During the first 12 months the hydrolysis mainly involved the anhydride groups. No significant difference was observed between pH 6 and pH 7. The third PEA (2b) only contained 5% of anhydride groups. It showed little degradation at pH 6 or pH 7 over a period of 12 month. A rapid degradation involving ester groups occurred at pH 4 or pH 9. All results together clearly indicate that, in addition to an erosion of the surface, a penetration of water into the hydrophobic PEA's occurs, followed by a more or less random hydrolysis of anhydride groups.
Characteristics of permeation and separation of xylene isomers through poly(vinyl alcohol) membranes containing cyclodextrin
Authors: Miyata Takashi , Iwamoto Tooru , Uragami Tadashi 
Published: April 2003

AbstractThe characteristics of permeation and separation for xylene isomers through poly(vinyl alcohol) membranes containing cyclodextrin (CD‐PVA membranes) were investigated by pervaporation and evapomeation. Evapomeation is more effective for the separation of xylene isomers through the CD‐PVA membrane than pervaporation. An increase in CD content gives rise to an increase in a p‐xylene‐permselectivity through the CD‐PVA membrane by evapomeation. This is attributed to the stronger affinity of CD for p‐xylene as compared with o‐xylene. Especially, the CD‐PVA membrane at a CD content of 40 wt.‐% shows a higher separation factor than has ever been reported. When the p‐xylene concentration in the feed is lower, the p‐xylene‐permselectivity is improved. The mechanism of permeation and separation for xylene isomers is discussed from the standpoint of solution‐diffusion theory.
Study of the structure of polyethylene and poly(tetrafluoroethylene) radiation grafted ion‐exchange copolymers
Authors: Turmanova Sevdalina , Dimitrova Antoaneta , Kostov George , Nedkov Emanuel 
Published: April 2003

AbstractCation‐ and anion‐exchange copolymers were synthesized by radiation induced copolymerization of acrylic acid and 4‐vinylpyridine onto polyethylene and poly(tetrafluoroethylene) (PTFE) films. The grafting was carried out by the direct method of single or multiple (discrete) irradiation by γ‐rays from a 60Co source. The grafting degree was from 10 to 121% for polyethylene and from 2.5 to 50% for poly(tetrafluoroethylene), depending on the irradiation dose (1–50 kGy). The calorimetric curves of the copolymers synthesized showed a glass transition temperature (Tg) at 333 ± 10 K. The enthalpies of melting and crystallization decreased with increasing degree of grafting. The data from wide angle X‐ray analysis indicated an increase of the amorphous part with degree of grafting. At lower grafting degrees of poly(acrylic acid) and poly(4‐vinylpyridine) (up to 15%) onto PTFE matrix, the size of the crystallites was found to increase. The penetration of the grafted functional monomer leads to partial deorientation of the initial LDPE film.
α,ω‐Dihydroxy telechelic poly(methyl methacrylate) via β‐scission (radical addition‐fragmentation) chain transfer polymerisation by macromonomer chain transfer agents, as prepared by catalytic chain transfer polymerisation
Authors: Haddleton David M. , Topping Clare , Hastings Jeremy J. , Suddaby Kevin G. 
Published: April 2003

Abstractα,ω‐Dihydroxy telechelic poly(methyl methacrylate) has been prepared by β‐scission (radical addition‐fragmentation) chain transfer polymerisation. Hydroxyethyl methacrylate dimer macromonomer prepared from catalytic chain transfer polymerisation and isolated as a pure compound is shown to be an efficient chain transfer agent. The mode of chain transfer is via β‐scission which results in the dimer breaking in half on addition to a propagating poly(methyl methacrylate) radical terminating the polymerisation and providing a hydroxyethyl methacrylate radical which reinitiates polymerisation. A combination of these two events leads to dihydroxy telechelic products, demonstrated to have a functionality of 2.05 by a combination of NMR and size exclusion chromatography (SEC). The chain transfer coefficients of these methacrylic macromonomers is concentration dependant exhibiting a type of “bootstrap” effect. This ultimately leads to a limiting low molecular weight telechelic product by the use of dimeric β‐scission chain transfer agents. A combination of high field NMR and matrix assisted laser desorption time‐of‐flight mass spectrometry has been utilised to demonstrate the structure of the products. The combination of catalytic chain transfer polymerisation and β‐scission chain transfer has been demonstrated to be a powerful tool in the controlled polymerisation of methacrylates by radical methodology.
Synthesis and properties of poly(1‐alkyl‐3‐methylene‐2‐pyrrolidone)s
Authors: Iskander George M. , Ovenell Toni R. , Davis Thomas P. 
Published: April 2003

AbstractA series of α‐methylene‐N‐alkyl‐2‐pyrrolidone monomers with varying length of the alkyl chain from C1 to C8 were synthesised. The monomers were subjected to free radical polymerisation to yield a range of polymers each with a different balance in hydrophobic/hydrophilic properties originating from the pyrrolidone moiety and the N‐alkyl chain. The equilibrium water content of polymers crosslinked with ethylene dimethacrylate were found to decrease with increasing alkyl chain length. The glass transition temperatures of the polymers are reported ranging from 98°C to ‐5°C on going from the methyl to the octyl derivative. The thermal degradation of the polymers was studied using thermogravimetric analysis and pyrolysis gas chromatography‐mass spectroscopy. The polymers were found to degrade at ca. 400°C predominantly via an unzipping mechanism. Pyrolysis at 450°C results in five products.
Thermal properties and crystallization behavior of poly(ether ether ketone ketone)/poly(ether biphenyl ether ketone ketone) copolymers
Authors: Shibata Mitsuhiro , Yosomiya Ryutoku , Jiang Zhenhua , Fang Zhijie , Wu Zhongwen 
Published: April 2003

AbstractThermal properties of poly(ether ether ketone ketone) (PEEKK)/poly(ether biphenyl ether ketone ketone) (PEDEKK) copolymers were investigated by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The glass transition temperature (Tg) increases from 154°C to 183°C as the content of PEDEKK units increases. The melting point (Tm) of the copolymers varied in the range between 314°C and 409°C and showed the behavior of eutectic type copolymer. From the investigation of the crystallization behavior of the copolymers, it was found that the cold‐crystallization temperature (Tc′) of the amorphous copolymers assumes a maximum value for the copolymer with a mole fraction of the PEDEKK segment (nB) of about 0.6, isothermally crystallized PEEKK and the PEEKK/PEDEKK copolymer exhibit double‐melting behavior.
Effect of styrene on the polymerization of acrylamide in inverse microemulsion
Authors: Bartoň Jaroslav , Juraničová Viera 
Published: April 2003

AbstractThe macroviscosity of a single‐phase toluene/styrene/sodium bis(2‐ethylhexyl)sulfosuccinate/water/acrylamide Winsor IV inverse microemulsion prior to polymerization as a function of the volume fraction ϕaw, of the dispersed aqueous (water + acrylamide) phase at 20°C reaches three distinct maxima of 16, 66, and 30 mPa ·;s for ϕaw values 25%, 46%, and 62%, respectively. At 60°C, the viscosity maxima practically vanish and the macroviscosity of the dispersion systems is in the range of 5–7 mPa · s. The overall maximum (co)polymerization rate of acrylamide and styrene increases with increasing ϕaw. On the other hand, an increase of the mass ratio styrene/toluene leads (for a given ϕaw value) to a decrease of the overall maximum (co)polymerization rate regardless of the nature of the initiator used. This points to an effective competition between monomer in the oil phase (slow homopolymerization of styrene and/or (co)polymerization of styrene with acrylamide dissolved in the oil phase) and monomer in the water pools of inverse micelles (rapid homopolymerization of a major part of acrylamide) for initiator radicals and/or (co)oligomer radicals.
Miscibility of phenoxy polymer/polyacrylate blends
Authors: Wu Chengpei , Wu Yiliang , Zhang Ruiyun 
Published: April 2003

AbstractThe miscibility of blends of phenoxy polymer 1 from bisphenol A and epichlorohydrin and polyacrylates is studied using differential scanning calorimetry (DSC) and Fouriertransform infrared (FTIR) spectroscopy. The DSC curves show that poly(alkyl acrylate)s are immiscible with phenoxy. IR spectra show that there exists weak hydrogen‐bonding interaction between poly(methyl acrylate) and phenoxy. The miscibility behavior of various phenoxy/polyacrylate blends cannot be satisfactorily explained by a non‐hydrogenbonded solubility parameter approach. It can be better explained by the polar and nonpolar solubility parameter approach.