bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transition‐metal‐catalyzed vinyl addition polymerizations of norbornene derivatives with ester groups
Authors: Breunig Stefan , Risse Wilhelm 
Published: April 2003

AbstractNorbornene derivatives containing ester substituents were submitted to Pd(II)‐catalyzed vinyl addition polymerization. The transition metal catalyst was found to tolerate the ester functionality. However, the rate of polymerization was reduced in comparison to the polymerization of norbornene. The polymerization of the pure exo‐isomers produced substantially higher yields than reactions of monomers containing a high proportion of the corresponding endo‐isomer. By varying the ester substituent, amorphous polymers with glass transition temperatures over the range of −40 to 268°C were synthesized. An approximately linear relationship of molecular weight to monomer conversion was established, and the non‐uniformity remained narrow (M̄w/M̄n ≈ 1,15 – 1,25) until high conversions for several of the exo‐isomers studied. This indicates that both chain transfer and chain termination are rare.
Gas transport of hydrocarbon gases through smectic‐A liquid‐crystalline elastomers
Authors: Reinecke Helmut , Finkelmann Heino 
Published: April 2003

AbstractThe transport behaviour of hydrocarbon gases through liquid‐crystalline (l.c.) elastomers is investigated. For different l.c. elastomers exhibiting the smectic‐A phase structure, diffusion and permeation coefficients and solubilities are measured as a function of temperature. The behaviour at the smectic‐A to isotropic phase transformation is discussed and the permeabilities of propane through different l.c. membranes are compared with respect to their network type, spacer length and end group of the mesogens. In methacrylate networks with high phase transformation enthalpies a discontinuous behaviour is observed at the smectic to isotropic phase transformation temperature Tc, as expected for a first‐order phase transformation. Depending on the chemical constitution of the membrane, the l.c. state can reduce or improve the gas transport compared to the isotropic state. With increasing flexibility of the membrane system — caused by a more flexible network, longer spacer or longer end group — the permeabilities exhibit significantly higher values. For all elastomers an increase of the ideal selectivities is observed in the smectic‐A phase.
Synthesis of frequency doubling polymeric materials, 2. Second‐order nonlinear optical properties of poled chromophore‐functionalized polystyrenes
Authors: Vanermen Guy , Samyn Celest , S'Heeren Gert , Persoons Andre 
Published: April 2003

AbstractThe synthesis and frequency doubling properties of nonlinear optical chromophore functionalized polystyrene with 4‐nitro‐ or 4‐cyano‐4'‐hydroxyazobenzene, or 2‐[2‐(4‐hydroxyphenyl‐ethenyl)]‐3,5‐dinitrothiophene are reported. The polymers with longer spacer length of the side chain chromophore show higher X(2) values, because of a better alignment under poling conditions. Values as high as 23,8 · 10−9esu at 1064 nm can be achieved. With a stronger acceptor group (3,5‐dinitronthiophene) a value of 22 · 10−9esu was achieved for a chromophore content which was even 4 times smaller.
Synthesis and properties of high‐molecular‐weight polyesters based on 1,4:3,6‐dianhydrohexitols and terephthalic acid
Authors: Storbeck Reinhard , Rehahn Matthias , Ballauff Matthias 
Published: April 2003

AbstractThe synthesis of high‐molecular‐weight polyesters based on 1,4:3,6‐dianhydro‐D‐sorbitol (DAS), 1,4:3,6‐dianhydro‐D‐mannitol (DAM) and 1,4:3,6‐dianhydro‐L‐iditol (DAI) is reported. The polymers were obtained by polycondensation in solution of the dianhydrohexitols with terephthaloyl dichloride and 2,5‐diethoxyterephthaloyl dichloride. The side groups of the latter monomer lead to a marked improvement of the solubility of the resulting polyesters which can be characterized by NMR techniques and osmometry. It is shown that all polyesters exhibit an excellent stability against thermal decomposition. Materials deriving from the polycondensation with terephthalic acid have glass transitions above 200°C if the molecular weight is high enough. The wide‐angle X‐ray analysis shows that polyesters deriving from terephthalic acid and DAM as well as DAI are semicrystalline. All results demonstrate that these polyesters partly deriving from renewable carbon sources present promising high Tg materials with excellent thermal stability.
Structure formation in solutions of atactic polystyrene in trans‐decalin
Authors: Arnauts J. , Berghmans H. , Koningsveld R. 
Published: April 2003

AbstractThe temperature‐concentration diagram for the system atactic polystyrene/trans‐decalinSystem. name: trans‐decahydronaphthalene.
was studied by optical observations and calorimetric investigations. A liquid‐liquid demixing interferes with the glass transition of the polymer‐solvent system. It results in the solidification of the solution. The binodal, the spinodal and the position of the critical point were investigated for a sample with narrow molecular weight distribution. The formation of different morphologies, based on different cooling processes, is illustrated.
Synthesis of a hexyl methacrylate‐terminated disaccharide monomer and study of its radically initiated homo‐ and copolymerization with styrene
Authors: Charreyre Marie‐Thérèse , Boullanger Paul , Pichot Christian , Delair Thierry , Mandrand Bernard , Llauro Marie‐France 
Published: April 2003

AbstractA new disaccharide monomer, 6(‐methacryloxyloxy)hexyl β‐D‐cellobioside (CHMA, 7h), was prepared through a five‐step procedure (starting from cellobiose), in which the glycosylation and esterification reactions have been optimized. Kinetics of radical homopolymerization in dimethyl sulfoxide solution were studied through 1H NMR, allowing the determination of the parameter kp/kt1/2. Copolymerizations with styrene (S) were also investigated, giving the reactivity ratios rS = 0,64 and rM = 0,08. Characterization of the various (co)polymers in terms of composition, microstructure and molecular weight was carried out using 1H and 13C NMR spectroscopy and gel‐permeation chromatography in tetrahydrofuran, respectively. A preferential syndiotactic configuration was clearly evidenced in the homopolymer.
Living cationic polymerization of styrene by 1‐chloroethylbenzene/tin(IV) chloride in chloroform
Authors: Kwon Oh‐Sig , Kim Yang‐Bae , Kwon Soon‐Ki , Choi Byong‐Seok , Choi Sam‐Kwon 
Published: April 2003

AbstractLiving cationic polymerization of styrene in the presence of 1‐chloroethylbenzene (1‐CEB)/SnCl4 as an initiating system has been investigated in chloroform at ‐15 to +20°C. The best results were obtained at ‐15°C. Under these conditions, the number‐average molecular weight (M̄n) of the products increases linearly with increasing monomer conversion. The molecular weight of the polymer produced could be further increased by adding additional monomer. The molecular weights are in good agreement with the calculated values assuming that one living polymer chain is formed per one 1‐CEB molecular. The molecular weight distributions of the polymers obtained are narrow (ratio of weight‐ to number‐average molecular weights 1,07 ≤ M̄w/M̄n ≤ 1,17). The living character of these polymerizations depends on the polarity of the solvent and on temperature.
Surface tension of poly[(1H,1H,2H,2H‐heptadecafluorodecyl)methylsiloxane]
Authors: Kobayashi Hideki , Owen Michael J. 
Published: April 2003

AbstractPoly[(1H,1H,2H,2H‐heptadecafluorodecyl)methylsiloxane] (PHDFDMS) was synthesized and the solid surface tension of its cross‐linked films was obtained from water, methylene iodide and various alkanes contact angle data. The value obtained from the Owens and Wendt geometric mean approach using water and methylene iodide data is 7,0 mN/m, the lowest value yet reported for a preformed fluorosilicone polymer. Surface tension values obtained from alkane contact angle data are higher, for example, the Zisman critical surface tension of wetting is 14,9 mN/m. These values fit the trends of other similar fluorinated polymers with the exception of a previous report that PHDFDMS has an anomalously high surface tension.
Melting behavior and crystalline order of ß‐crystalline phase poly(propylene)
Authors: Shi Guan‐yi , Zhang Xiao‐dong , Cao You‐hong , Hong Jie 
Published: April 2003

AbstractDifferential scanning calorimetry and X‐ray diffraction experiments on ß‐nucleated poly(propylene) were made on samples crystallized at different temperatures. The crystal perfection was shown to vary with crystallization temperature. The observed multiple peaks could be related to a ß1‐phase with defective inclination of the chains, a recrystallized or original ß2‐phase of more perfect inclination, and the α‐phase.
Xylan derivatives: aromatic carbamates
Authors: Vincendon Marc 
Published: April 2003

AbstractXylan, which is a natural polysaccharide extracted from plant cell walls, is a branched polymer. Linear xylan can be easily obtained through preferential cleavage of the branched sugar units. Xylan is a polyhydroxylated polymer, which is difficult to dissolve in classical organic solvents. The complete substitution of the hydroxyl groups regularly distributed along the xylan chain has been achieved via their reaction with aromatic monoisocyanates. Xylan‐2,3‐bis(phenyl carbamate) (5) and xylan‐2,3‐bis(tolyl carbamate) (6) were obtained with good yield. They were fully characterized by using spectroscopic methods (IR, 1H and 13C NMR). These new xylan derivatives are thermoplastic at high temperatures and decompose beyond 300°C.
Polylactones 21. Polymerization of L,L‐lactide and rac‐D,L‐lactide with hematin and related porphyrin complexes
Authors: Kricheldorf Hans R. , Boettcher Caroline 
Published: April 2003

AbstractThe polymerization of L,L‐lactide was conducted in bulk at 120, 150 and 180°C. Hematin (1a), hemin (1b), 5,10,15,20‐tetraphenylporphiniron(III) chloride, 2,3,7,8,12,13,17,18‐octaethyl‐21H, 23H‐porphiniron(III) chloride (3) and chlorophyllin (4a) were used as initiators. Moderate yields and moderate molecular weights up to 15000 were obtained. Gradual racemization was observed with increasing reaction time and temperature. The results obtained with chlorophyllin and benzylated chlorophyllin suggest an anionic polymerization mechanism for the former initiator. When rac‐D,L‐lactide was polymerized with hematin in bulk at 120, 150 and 180°C, yields up to 74% and molecular weights up to 104 were found. The polymerization of meso‐D,L‐lactide gave lower yields and molecular weights. Both 1H‐ and 13C NMR spectroscopy indicate the formation of nearly random stereosequences in all polymerization of rac‐ and meso‐D,L‐lactide.
Synthese von neuen monomeren schwefelhaltigen acryl‐ und methacrylsäureamid‐derivaten aus 3‐thiazolinen
Authors: Martens Jürgen , Kramer Uwe , Gertje Anja , Schütte Martina 
Published: April 2003

AbstractAcrylamides containing heteroatoms N, S or O are effective compounds to influence the properties of polymers. On the one hand they determine the chemical and physical behaviour of the synthetic materials, on the other hand they offer new possible applications for such compounds. In this paper a synthetic method affording a new class of monomers prepared from simple educts is described. Thus, 3‐thiazolines 3 are allowed to react with alkenoyl chlorides (e. g. acryloyl chloride) to give 3‐alkenoyl‐4‐chlorothiazolidines. Upon hydrolysis the 3‐alkenoyl‐4‐hydroxythiazolidines 6a–d, 7a, b, 8a–d and 9a, b are obtained. Starting from 3‐alkenoyl‐4‐chlorothiazolidines, several 3‐alkenoyl‐4‐methoxythiazolidines 6e, f, 7c and 9c have been synthesized, too.
Spontaneous polymerization of amphiphilic vinyl monomers, 2 spontaneous polymerization of sodium alkyl 2‐hydroxy‐3‐methacryloyloxypropyl phosphates in micellar and inverse micellar systems
Authors: Yasuda Yutaka , Rindo Katsuhiko , Tsushima Rikio , Aoki Shuzo 
Published: April 2003

AbstractThe spontaneous polymerization of sodium alkyl 2‐hydroxy‐3‐methacryloyloxypropyl phosphates (Cn‐AHMP) was investigated in the temperature range from 35°C to 80°C in water and in benzene. The polymerization activity in both solvents changed with the alkyl chain length in the order: C12 > C8 > C14 ≫ C16. Similarly to the C12 monomer, C14‐AHMP only polymerizes above the critical micelle concentration (cmc), proving that micelle‐formation is essential for the spontaneous polymerization. The polymerization of the C8 analogue occurs even a little below the cmc, in contrast to C12 ‐ and C14‐AHMP. This behaviour suggests the existence of smaller aggregates than the micelle below the cmc in water. The polymerization of C16‐AHMP did not take place spontaneously in both solvents, in spite of the formation of micellar aggregates in water. The lack of polymerization ability is related to the inactivity to generate initiating radical species in the micellar system.
Blends of poly(hydroxy ether of bisphenol‐A) with poly(2‐vinylpyridine) and poly(4‐vinylpyridine)
Authors: de Ilarduya Antxon Martínez , Eguiburu José L. , Espi Enrique , Iruin Juan J. , Fernández‐Berridi María J. 
Published: April 2003

AbstractPoly(hydroxy ether of Bisphenol‐A), so‐called Phenoxy resin (structure‐based IUPAC name: poly[oxy(2‐hydroxytrimethylene)oxy‐1,4‐phenyleneisopropylidene‐1,4‐phenylene]), is shown to be miscible with poly(4‐vinylpyridine) (P4VPy, poly[1‐(4‐pyridyl)ethylene]) and poly(2‐vinylpyridine) (P2VPy, poly[1‐(2‐pyridyl)ethylene]) over the entire composition range. Miscibility of the blends is evidenced by their glass transition temperatures being intermediate between the pure polymers for the blends of P4VPy and Phenoxy but being higher than the average for the case of the P2VPy/Phenoxy blends. Hydrogen bonding between the components was detected through infrared spectroscopy, which was also used in the study of mixtures of low‐molecular‐weight analogues, in order to calculate the free energies of mixing according to the association model of Painter and Coleman.
Poly(phthalidylidenearylene)s. Gelation in the homopolycondensation of 3‐aryl‐3‐chlorophthalides
Authors: Zolotukhin Mikhail G. , Skirda Vladimir D. , Sedova Elvira A. , Sundukov Vladimir I. , Salazkin Sergei N. 
Published: April 2003

AbstractThe Friedel‐Crafts homopolycondensations of 3‐(4‐biphenyly)‐3‐chlorophthalide (1 a), 3‐(2‐fluorenyl)‐3‐chlorophthalide (1 b), 3‐(4‐phenoxyphenyl)‐3‐chlorophthalide (1 c), 3‐(4‐phenylthiophenyl)‐3‐chlorophthalide (1 d) were studied. The homopolycondensation of 1 a was found to give linear, fully soluble polymers. A gelation, depending on reaction parameters, can occur in the reactions of 1 b–1 d. The methylene group of 1 b was shown to be reactive in the course of synthesis, giving cross‐links. Using the NMR pulsed gradient spin echo method, it was found, that degradation of macromolecular chains in the homopolycondensation of 1 c is followed by gelation. A proposed mechanism of gelation is based on the transformation of intermediate acyloxonium complexes. Similar transformations of acyl‐sulfonium complexes are suggested to occur in the course of the homopolycondensation of 1 d.
Microspheres prepared with a temperature‐responsive macromonomer
Authors: Takeuchi Shigeya , Oike Mitsuru , Kowitz Christoph , Shimasaki Choichiro , Hasegawa Kiyoshi , Kitano Hiromi 
Published: April 2003

AbstractA macromonomer was prepared from succinimido methacrylate and poly(N‐isopropylacrylamide) (PIPA) with an amino end group. The macronomer (MA‐PIPA) obtained shows a temperature‐responsive transition phenomenon from coil to globule in water at about 36°C. For the copolymer of MA‐PIPA with acrylamide (ratio of monomer residues of N‐isopropylacrylamide (IPA) and acrylamide (AAm) 10:3), the transition temperature of the PIPA chain was the same as that of the macromonomer, whereas the transition temperature of a linear copolymer of IPA and AAm (ratio of the monomer residues 10:3) was much higher than that of PIPA (52°C). Microspheres were prepared by emulsion polymerization of the macromonomer and styrene in the presence of sodium dodecylsulfate. The microspheres obtained show a temperature responsiveness in the critical flocculation concentration. The macromonomer prepared here can be used as a component of temperature‐sensitive devices in various forms.
Lyotropic mesophase of imogolite, 3 observation of liquid crystal structure by scanning electron and noval polarized optical microscopy
Authors: Donkai Nobuo , Hoshino Hiroshi , Kajiwara Kanji , Miyamoto Takeaki 
Published: April 2003

AbstractThe mesophase (lyotropic liquid crystal) of the inorganic rod‐like polymer, imogolite, displays a typical fingerprint texture under a polarized optical microscope (POM), although the mesophase reveals no circular dichroism. The scanning electron microscope revealed a honeycomb structure of thin sheets having pleats in the freeze‐dried sample prepared from the mesophase solution, and POM shows also a fingerprint texture from the same sample. A novel polarized optical microscopic observation procedure was introduced to eliminate the contrast variation and extinction due to the zero amplitude effect which depends on the orientational variation of anisotropic bodies with respect to a polarizer direction under the crossed Nicols. Various textures of lyotropic imogolite liquid crystals were observed with the procedure, and the results were accounted for by a honey‐comb structure of curled thin sheats having pleats. The honey‐comb model is consistent with the observation by scanning electron microscopy on the freeze‐dried sample.
Synthesis of isotopically labelled monomers and polymers of 4‐hydroxybenzoic acid and 6‐hydroxy‐2‐naphthoic acid
Authors: Nieβner Norbert , Mühlebach Andreas , Lyerla James R. , Facey Glenn A. , Fyfe Colin A. 
Published: April 2003

AbstractSynthesis and characterization of 4‐acetoxybenzoic acid and 6‐acetoxy‐2‐naphthoic acid, labelled with deuterium in the rings and with carbon‐13 and oxygen‐17 in the carboxyl‐positions, and of the corresponding homo‐ and copolyesters, are described. Kinetic studies of hightemperature deuteration were performed on 6‐hydroxy‐2‐naphthoic acid. Mass spectrometry provides information about the degree of labelling with 2H, 13C and 17O. Composition and molecular weight of isotopically labelled polymers were monitored by 1H NMR after digestion in basic methanol. The thermal behavior was investigated by differential scanning calorimetry and thermogravimetry.
Die katalyse der 1,4‐cis‐polymerisation des butadiens mit dem kationischen C12‐allylnickel(II)‐komplex [Ni(C12H19)]SbF6
Authors: Taube Rudolf , Langlotz Jochen 
Published: April 2003

AbstractThe catalytic properties of η3,η2η2‐dodeca‐2(E),6(E),10(Z)‐trien‐1‐yl‐nickel(II) hexafluoroantimonate are investigated in some detail. Under standard conditions the complex catalyses the polymerization of butadiene in toluene at room temperature with an extremely high activity of nearly 15000 mol C4H6/(mol Ni · h) and a cis selectivity up to 90%. The activity increases linearly with both the nickel and the butadiene concentration. No change in the selectivity and in the limiting viscosity number [n] has been found in the investigated range of concentration and temperature.
Polylactones, 22 ABA triblock copolymers of L‐lactide and poly(ethylene glycol)
Authors: Kricheldorf Hans R. , Meier‐Haack Jochen 
Published: April 2003

AbstractTriblock copolymers were prepared from L‐lactide and a poly(ethylene glycol) of M̄n = 1020. With GeO2 and SnO2 only low conversions were obtained, regardless of the reaction temperature. Sb2O3 caused partial racemization, and only SnO gave satisfactory results. When other samples of poly(ethylene glycol) were used (e.g., with M̄n = 600 or 3250), partial racemization occurred even with SnO. However, with Sn(II) 2‐ethylhexanoate, racemization‐free triblock copolymers were obtained under the reaction conditions used. The results of the characterization indicate that the triblock copolymers possess unimodal molecular weight distribution. The lactide blocks crystallize in the α‐modification and suppress in most, but not all, cases the crystallization of the poly(ethylene glycol) blocks. The crystallization of long poly(ethylene glycol) blocks observed in several cases indicates a triphasic character of these samples.
The thermal behaviour of low‐molecular‐weight poly(3‐decylthiophene)
Authors: Bolognesi Alberto , Porzio William , Provasoli Francesco , Ezquerra Tiberio 
Published: April 2003

AbstractA detailed study on the thermal behaviour of low‐molecular‐weight poly(3‐decylthiophene) (Mw = 5700 by gel permeation chromatography) was performed using differential scanning calorimetry, X‐ray diffraction, optical microscopy and FTIR techniques. A polymorphism for this polymer was clearly shown: namely two different crystalline phases and a mesophase, probably nematic. A structural model for a 3‐dimensional phase was derived. Finally the conditions under which each phase can be obtained were determined.
Acetylene‐terminated amide oligomers
Authors: Martinez Francisca , de Abajo Javier , Mercier Regis 
Published: April 2003

AbstractSix new acetylene‐terminated (AT) oligomers were synthesized by reaction of 3‐ethynylbenzoyl chloride and 4‐ethynylbenzoyl chloride with three aromatic diamines containing four aromatic rings. The functionalization led quantitatively to AT oligomeric diamides of well defined composition, as confirmed by IR, 1H NMR and 13C NMR spectroscopy. The materials exhibited comparatively high melting points, over 200°C; thus, heating promoted curing before melting or simultaneously with melting, with the only exception of one sample that could be isolated in the amorphous state. Heating at 325°C led to insoluble cured materials, with excellent thermal resistance and glass transition temperatures Tg around 300°C.
Influence of the block length on the structure of micelles formed by polystyrene‐block‐poly(ethylene‐co‐propene) in octane and 5‐methyl‐2‐hexanone
Authors: Quintana José R. , Villacampa Manuel , Katime Issa A. 
Published: April 2003

AbstractThe influence of molar mass and chemical composition of the copolymer on the structural parameters of copolymer micelles was investigated. Two polystyrene‐block‐poly(ethylene‐co‐propene) copolymers with the same polystyrene block length but different poly(ethylene‐co‐propene) length were used. The micelles were studied in solutions of octane and 5‐methyl‐2‐hexanone, selective solvents for poly(ethylene‐co‐propene) (PEP) and polystyrene (PS) blocks, respectively. Static light scattering and viscosity measurements were carried out in order to determine the weight‐average molar mass, radius of gyration, second virial coefficient and hydrodynamic radius of the micelles. The association number of the micelles depends on the location of the largest copolymer block in the micelle structure. An influence of the copolymer structure on the micelle dimensions was also found.