bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interpolymer association between poly(vinylpyridines) and poly(mono‐n‐alkyl itaconates). Effect of the n‐alkyl substituent
Authors: Velada José L. , Cesteros Luis C. , Katime Issa 
Published: April 2003

AbstractThe binary polymeric systems formed by some poly(mono‐n‐alkyl itaconates) and poly(2‐vinylpyridine) or poly(4‐vinylpyridine) are studied. Depending on the solvent, two different types of material have been synthesized. On the one hand, using methanol as common solvent, we have obtained solid polymer‐polymer complexes the composition of which is determined by the initial mixing conditions. On the other hand, pyridine avoids the complexation process, allowing to obtain a true solution of both polymers and, therefore, a solid polymer blend of known composition by solvent casting. Yields of the complexation and stoichiometries of the polymer‐polymer complexes have been analysed. In this way, a favoured composition in the range from 3:2 to 1:1 for the mole ratio (referring to repeating units) ratio poly(mono‐n‐alkyl itaconate):poly(vinylpyridine) was observed depending on the poly‐(mono‐n‐alkyl itaconate used). Differential Scanning Calorimetry and thermogravimetry have been employed to study the thermal behaviour of complexes and blends. Viscometry measurements have been performed to analyse the interactions in solution. One of the aims of this work has been to analyse the effect of the side group of the poly‐(mono‐n‐alkyl itaconate) in the mixing process as well as in the characteristics of the final products. In this way, higher complexation yields have been obtained using poly‐(mono‐n‐alkyl itoconates) with longer n‐alkyl side groups due to the additional stabilisation by solvophobic interactions. On the other hand, the poly(mono‐n‐alkyl itaconates) with longer n‐alkyl groups form polymer‐polymer complexes with a higher proportion of poly(4‐vinylpyridine), presumably due to their slower kinetics of complexation.
Télomérisation en milieu aqueux, 2. Étude cinétique de la télomérisation de l'acide acrylique avec l'acide thioglycolique
Authors: Boutevin Bernard , Rigal Gérard , El Asri Mohammed , Lakhlifi Tahar 
Published: April 2003

AbstractThe telomerization of acrylic acid with thioglycolic acid initiated with hydrogen peroxide in aqueous medium is presented. In order to better control this reaction, the decomposition of H2O2 was first investigated by means of differential scanning calorimetry (DSC), leading to a very high value of the dissociation rate constant (kd), and then studied by volumetry in the presence of a mercaptan. This second method gave a higher value of kd (by about 6 orders of magnitude at 50°C). From the latter value, the ratio fkP2/kTe and the transfer constant of thiogiycolic acid, Ct, were determinated and compared with those reported in the literature. The kinetical parameters, obtained from theoretical and experimental values of DPn and the conversion of the monomer are in good agreement and allow to prepare telomers of acrylic acid with controlled chain length.
Planar para‐phenylene oligomers
Authors: Grimme Julian , Scherf Ullrich 
Published: April 2003

AbstractPlanar, methylene‐bridged quinque‐ and septiphenyl oligomers were synthesized as soluble, hitherto unknown compounds. The series of homologous and planar ladder‐type oligophenyls (ter‐, quinque‐, septiphenyl) was characterized especially with respect to their optical properties (absorption and emission) as function of increasing chain length, and compared to the corresponding ladder‐type polyphenylene. An effective conjugation length of about 12 benzene rings was determined within this series of planar oligo‐ and polyphenylenes.
Uncrosslinked epoxide‐amine addition polymers, 44. Linear arylamine/2,2‐bis[4‐(2,3‐epoxypropoxy)phenyl]‐propane addition polymers — synthesis and properties
Authors: Klee Joachim E. , Grützner Rolf‐Egbert , Hörhold Hans‐Heinrich 
Published: April 2003

AbstractThe addition polymerization of aromatic disecondary diamines and 2,2‐bis[4‐(2,3‐epoxypropoxy)phenyl]propane (DGEBA) leads to linear high molecular weight epoxide‐amine addition polymers with number‐average molecular weights ranging from 10 000 to 20 000 g/mol. Depending on the amine structure, their glass transition temperatures were estimated between 80 and 140°C. The fractionation of the high molecular weight addition polymers allows the separation of cyclic oligomers and the separation of polymers with narrow molecular weight distribution (M̄w/M̄n = 2.4–2.8). In dilute solution, predominantly cyclic oligomers were formed. Hence, they were prepared in such solutions and isolated by means of column chromatography. Their cyclic structure is proved by combination of M̄ values and 13C NMR spectra.
Synthesis and characterization of poly(2,5‐dipropargyloxy‐1,4‐phenylenevinylene) and its copolymers with 1,4‐phenylenevinylene
Authors: Shim Hong‐Ku , Hwang Do‐Hoon , Yoon Chong‐Bok 
Published: April 2003

AbstractPoly(2,5‐dipropargyloxy‐1,4‐phenylenevinylene) (PDPPV) and its copolymers were prepared as thin films via the organic‐soluble and water‐soluble precursor routes. Elimination and crosslinking reactions could be controlled by the temperature. Crosslinked PDPPV is stable up to 450°C. The conductivity values of undrawn and drawn FeCl3‐doped PDPPV films are 5.0 × 10−2 and 2.0 × 10−1 Sċcm−1, respectively. The third‐order nonlinear optical susceptibility, χ(3), for the PDPPV film was investigated by degenerate four‐wave mixing (DFWM) technique at 602 nm wavelength, and found to be 2.3 × 10−10 esu.
Morphological study of bacterial poly(3‐hydroxybutyrate‐co‐3‐hydroxypropionate)
Authors: Ichikawa Masafumi , Nakamura Kazuhiro , Yoshie Naoko , Asakawa Naoki , Inoue Yoshio , Doi Yoshiharu 
Published: April 2003

AbstractThe solid‐state structure of a bacterially synthesized copolyester, poly(3‐hydroxybutyrate‐co‐3‐hydroxypropionate), P(3HB‐co‐3HP), with the 3HP content ranging from 0 to 37 mol‐%, was analyzed by 13C solid‐state high‐resolution NMR, X‐ray diffraction, differential scanning calorimetry and optical microscopy. For the copolymers containing up to about 40 mol‐% 3HP, it was confirmed from the X‐ray diffraction measurement that the crystallographic parameters are similar to those of P(3HB) homopolymer and the degree of crystallinity decreases as the 3HP content increases. From the measurement of 13C spin‐lattice relaxtion time (T1c) using solid‐state high‐resolution 13C NMR, it was concluded that the crystalline region is composed only of 3HB units, suggesting that the cocrystallization of 3HB and 3HB units in the same crystal lattice does not occur in P(3HB‐co‐3HP). This conclusion is supported by the thermal properties and the rate of spherulite growth.
Synthesis and electroluminescent properties of quaterphenyl and sexiphenyl containing copolymers
Authors: Keegstra Menno A. , Cimrová Vera , Neher Dieter , Scherf Ullrich 
Published: April 2003

AbstractCopolymers containing quaterphenyl and sexiphenyl units in which the solubility was introduced by spacer groups were prepared and investigated. Photoluminescence of the compounds appears in the blue region of the visible light. Blue light emitting electroluminescent devices based on the blends of the quaterphenyl copolymer and poly(N‐vinylcarbazole) with indium‐tin oxide(ITO) and aluminium as hole‐ and electron‐injecting electrodes, respectively, were fabricated. Further, the quaterphenyl copolymer was found to be nematic between 236 and 244°C.
Synthesis and polymerization of bis(hexamethylene carbonate) and bis(2,2,3,3,4,4,5,5‐octafluorohexamethylene carbonate)
Authors: Weilandt Karl D. , Keul Helmut , Höcker Hartwig 
Published: April 2003

AbstractBis(hexamethylene carbonate) (HC) and bis(2,2,3,3,4,4,5,5‐octafluorohexamethylene carbonate) (FHC) were synthesized starting from the corresponding diols and diphenyl carbonate in a two‐step reaction: (i) first polycondensation occurs, (ii) then ring‐closing depolymerization leads to HC and FHC, respectively. The polymerization of HC is performed withsec‐butyllithium in toluene solution, and the corresponding polymer is obtained in high yield. Polymerization of FHC is perfomed either in tetrahydrofuran solution with dibutylmagnesium as initiator or in the melt with dibutyltin dimethoxide as initiator. Poly(HC) is a semicrystalline polymer with a melting point of 54.0°C and a glass transition temperature of −51.3°C. Poly(FHC) was obtained either as a semicrystalline material with a melting point of 40.8°C or an amorphous material with a glass transition temperature of −39.8°C. Copolymers of HC and FHC with a diad ratio of 19:60:21 were obtained by melt polymerization with dibutyltin dimethoxide as initiator. The ringchain equilibrium established during polymerization was studied for HC in toluene solution and for FHC in the melt. The concentration of the cyclic oligomers at equilibrium was determined, and for poly(HC) the characteristic ratio was calculated to be 10.0 ± 1.0.
Novel water‐soluble block copolymers of dimethylaminoethyl methacrylate and dihydroxypropyl methacrylate
Authors: Hoogeveen Nynke G. , Stuart Martien A. Cohen , Fleer Gerard J. , Frank Willy , Arnold Manfred 
Published: April 2003

AbstractIn this publication we describe the synthesis and properties of a novel type of block copolymer. The anionically synthesised block copolymer consists of a neutral, watersoluble block (2,3‐dihydroxypropyl methacrylate, HMA) and a pH‐dependently charged one (2‐dimethylaminoethyl methacrylate, AMA). The adsorption on silica and its effect on the colloidal stability were evaluated. The adsorbed amount is mainly determined by the electrostatics, which leads to a maximum adsorbed amount at low AMA content. The block copolymers tend to destabilise colloidal silica, due to a charge neutralisation upon adsorption, which is not compensated by the formation of a steric layer.
Poly{arylene‐alt‐[bis(1‐methylpyrrolylene)]}s, 1. Synthesis and electrochemical polymerization of terarenes
Authors: Geißler Uwe , Hallensleben Manfred L. , Rohde Nils 
Published: April 2003

AbstractNovel alternating conjugated copolymers were prepared by electrochemical polymerization of defined bis(1‐methylpyrrol‐2‐yl)arenes. The comonomers were synthesized by the nickel‐catalyzed coupling reaction (Kumada synthesis) of 1‐methylpyrrol‐2‐yl anion with various dibromoarenes. The monomers were characterized via common techniques, such as ultraviolet/visible (UV/Vis), proton nuclear magnetic resonance (1H NMR), 13C NMR, infrared (IR) and mass spectroscopy (MS). All monomers show irreversible electrochemical behavior and could therefore be polymerized to conducting polymers. The resulting copolymers reveal a conductivity in the range of 10‐2 S/cm to less than 10‐6 S/cm. The conductivity mainly depends on steric hindrance between the aromatic rings. A high decoupling of the conjugated systems could be observed in case of the anthracene/bis(1‐methylpyrrole) copolymer, which is due to the highest torsion angle between the rings of the series. Additionally, in the case of the furan derivative a soluble copolymer is formed under certain conditions in the reduced state.
Highly stereoelective polymerization of rac‐(D,L)‐lactide with a chiral schiff's base/aluminium alkoxide initiator
Authors: Spassky Nicolas , Wisniewski Muriel , Pluta Christian , Le Borgne Alain 
Published: April 2003

AbstractA chiral Schiff's base/aluminium alkoxide initiator bearing a ligand derived from R‐(+)‐1,1′‐binaphthyl‐2,2′‐diamine was synthesized and used for the stereoelective polymerization of rac‐(D,L)‐lactide. Rather high stereoelectivity is observed: a polymer with 88% enantiomeric enrichment in D units is obtained at 19% conversion. At high conversions a stereocomplex between D‐ and L‐enriched stereocopolymers is formed. The polymerization reaction shows living type features, and narrow molecular weight distributions (M̄w/M̄n = 1,05–1,30) are obtained up to very high conversions. This indicates that transesterification reactions do not occur significantly with this sterically hindered initiator.
Reactivity ratios in group transfer copolymerization of methyl methacrylate/ethyl methacrylate and methacrylonitrile/methyl methacrylate systems obtained by semi‐integral and integral methods
Authors: Çatalgil‐Giz Huceste 
Published: April 2003

AbstractThe monomer reactivity ratios for the methyl methacrylate/ethyl methacrylate (MMA/EMA) and methacrylonitrile/methyl methacrylate (MAN/MMA) systems are calculated by linearized semi‐integral and nonlinear fully integral methods. For the MMA/EMA system, rMMA values obtained by various methods are between 1.24 and 1.25 and rEMA values between 0.30 and 0.34. For MAN/MMA system, rMAN values are between 3.2 and 3.8 and for rMMA an upper bound can be determined, i.e., rMMA<0.05. The results show that previous values obtained by the linearized method (the initial Kelen‐Tüdős method) overestimate the reactivity of the less active monomer.
Synthesis and characterization of some novel polyamides containing diacetylene side groups
Authors: Fomina Lioudmila , Vega Adriana , Fomine Sergei , Gaviño Ruben , Ogawa Takeshi 
Published: April 2003

AbstractA series of novel polyamides containing diacetylene groups as side chains were prepared by Cadiot‐Chodkiewcz‐coupling of polymer precursors bearing 2‐propynyloxy side groups with 4‐bromo‐3‐butyn‐1‐ol. The conversion of the acetylenic groups was in the range of 87.5–96.5% depending on the chemical structure of the polymer backbone. The polymers are highly amorphous and undergo random cross‐linking on heating. Thermally treated polymer films show third‐order nonlinear optical susceptibility χ(3) of the order of 10−10 esu (= 10−18m5/V2).
Chromatographical investigation and mass spectrometry of cyclic polyimides by matrix‐assisted laser desorption
Authors: Kottner Nils , Bublitz Renate , Klemm Elisabeth 
Published: April 2003

AbstractThe Diels‐Alder addition polymerization of bispyrone 1 with 2 mol bismaleimide 2 was shown to lead to cyclic polyimides 3 (64%, M̄n = 15 000 g/mol) and to cyclic oligomers (36%) applying by gel‐permeation chromatography analysis (GPC) and by means of matrix‐assisted laser desorption/ionisation technique (MALDI).
Free radical “grafting from” hyperbranched polyesters based on polymeric azo initiators
Authors: Brenner Axel R. , Voit Brigitte I. 
Published: April 2003

AbstractAromatic and aliphatic hyperbranched polyesters were prepared by AB2polycondensation process. The highly branched, functional structure of these polymers leads to excellent solubility in combination with low solution viscosities. Varied numbers of the functional groups of the hyperbranched structures were modified with azo functions which are able to initiate free radical polymerization. An increase in temperature in the presence of the vinyl monomers methyl methacrylate (MMA), butyl methacrylate (BMA), styrene (S), or acrylamide (AA) results in “grafting from” the hyperbranched structure. Using this method several graft products were synthesized with variations in structure, number, and size of the graft arms. Gel‐permeation chromatography (GPC) with universal calibration and viscosity measurements indicate a strong influence of the hyperbranched core on the properties of the graft product. It was possible to control the phase behavior of the graft products from two phases to homogeneous by the ratio hyperbranched polyester: grafted monomer. The film forming properties which are very poor for unmodified hyperbranched polyester were improved by grafting with linear polymer chains.
Chromatographic investigations of macromolecules in the critical range of liquid chromatography, 10. Polymer blend analysis using a viscosity detector
Authors: Pasch Harald , Rode Karsten 
Published: April 2003

AbstractBinary polymer blends were separated by liquid chromatography at the critical point of adsorption. By operating at chromatographic conditions corresponding to the critical point of one blend component, the blends were separated regardless of the molar mass distributions of the components. After the separation step both components were precisely detected by an on‐line capillary viscometer. In contrast to refractive index detection, where a strong solvent peak appears in most cases, the viscosity signal is not affected by sight deviations in the mobile phase composition. Under critical conditions of adsorption of one component both blend components exhibit normal Mark‐Houwink behaviour. Therefore, the viscosity detector in conjunction with a concentration detector can be used for determining the molar mass distribution of both blend components.
Fluorescence study of the microstructure of a lyotropic liquid‐crystalline polyester substituted with sulfonato and nitro groups
Authors: Takahashi Hiromitsu , Horie Kazuyuki , Yamashita Takashi , Machida Shinjiro , Hannah David T. B. , Sherrington David C. 
Published: April 2003

AbstractThe fluorescence behaviour of a lyotropic liquid‐crystalline polyester substituted with sulfonato and nitro groups, poly[potassium oxy(x‐sulfonato‐1,4‐phenylene)oxy(x‐nitroterephthaloyl)] (1), was studied in various phases by changing the polymer concentration. This liquid‐crystalline polymer is soluble in several organic solvents and water. The observed fluorescence is originated from complexes between the potassium sulfonate‐substituted aromatic moiety and the nitro‐substituted aromatic moiety, and also from the dimer of the potassium sulfonate‐substituted moiety. From the results of fluorescence intensity changes with concentration, the change of phase in this lyotropic liquid‐crystalline system is suggested to occur gradually. By comparing the fluorescence behaviour in various phases with those of model compounds, the microstructure of the liquid‐crystalline state can be evaluated to some extent.
Structure and dynamics of polyelectrolyte‐surfactant complexes as revealed by solid state NMR
Authors: Antonietti Markus , Radloff Detlev , Wiesner Ulrich , Spiess Hans Wolfgang 
Published: April 2003

Abstract13C‐CP/MAS‐NMR (cross‐polarization magic angle spinning), 2D‐WISE (wideline separation experiment) and 1H‐spin diffusion experiments allow to gain new insight into the structure and dynamics of solid polyelectrolyte‐surfactant complexes, a material with pronounced mesophase formation. Experiments were performed on two different complexes of polystyrene sulfonate and octadecyltrimethylammonium or tetradecyltrimethylammonium counterions, PSS‐C18 and PSS‐C14. The strong mobility differences between the ionic and alkyl phase in the lamellar complex PSS‐C18 are reflected in the NMR behavior: in the surfactant tails, a mobility gradient towards the terminal methyl group is observed. This fact as well as a high content of gauche conformations suggest a non‐interdigitating morphology of the tails at room temperature. The behavior changes during cooling below an endothermic transition centered at 255 K where a high trans content and a homogenization of the side chain dynamics is observed. We attribute this transition which is invisible in the X‐ray experiments to the formation of a highly transoid, interdigitated phase of the surfactant tails which is however not crystallized in a classical sense. 1H‐spin diffusion experiments allow to estimate the distance between mobile and immobile regions of the sample. For the complex PSS‐C14, the length scale determined by NMR is essentially that of the primary lamellar structure. For PSS‐C18, a characteristic length of the density fluctuations within the proposed undulated lamellar structure is estimated.
γ‐ray polymerization of a mesogenic methacrylate in the crystalline, liquid crystalline and liquid state: kinetics, molecular weight distribution and conversion‐dependent phase behaviour
Authors: Hohn Wilfried , Tieke Bernd 
Published: April 2003

AbstractThe γ‐ray polymerization of mesogenic 4‐methoxy‐4′‐(6‐methacryloyloxyhexyloxy)biphenyl (1) was investigated. 1 can be polymerized in the crystalline, in the liquid crystalline and in the molten state. The rate of polymerization increases from the crystalline to the melt phase. In order to reach 90% conversion to polymer in melt, smectic and crystalline phase, radiation doses of 10, 40 and more than 120 kGy are necessary. Melt polymerization leads to a weight‐average molecular weight of about 1 × 106 independent of the conversion to polymer. In the smectic and crystalline phase the corresponding molecular weights are about 3.8 × 105 and 4.1 × 104 at low conversion, and shifted to 2.6 × 105 and 3.9 × 104 at high conversion. The polydispersity generally increases with the γ‐ray dose and the reaction temperature. The origin of the different reaction rates and molecular weight obtained in the various phases is discussed in terms of the mobility of growing chain ends and residual monomer, which influences chain growth and termination and thus the kinetic chain length. Differential scanning calorimetry (DSC) of partially polymerized samples was used to describe the conversion‐dependent phase behaviour. Optical microscopy showed that the melt polymerization at 78.5°C proceeds under phase separation into a liquid, monomer‐rich and a solid, polymer‐rich phase. As a consequence, liquid monomer samples solidify upon γ‐irradiation once a higher conversion to polymer is reached.
Polyanhydrides, 9. Thermotropic poly(ester‐anhydride)s derived from naphthalene‐2,6‐dicarboxylic acid and biphenyl‐4,4′‐dicarboxylic acid
Authors: Kricheldorf Hans R. , Jürgens Claas 
Published: April 2003

AbstractTwo series of thermotropic poly(ester‐anhydride)s, LC‐PEAs, were studied. The first series was prepared by polycondensation of naphthalene‐2,6‐dicarbonyl dichloride with silylated 4‐hydroxybenzoic acid, silylated and substituted 4‐hydroxybenzoic acids or silylated 6‐hydroxy‐2‐naphthoic acid. A second analogous series of LC‐PEAs was prepared by means of biphenyl‐4,4′‐dicarbonyl dichloride. Most LC‐PEAs were semicrystalline materials with melting temperatures (Tm) in the range of 280−400°C. All LC‐PEAs formed a nematic melt above Tm, but due to the high temperatures the isotropization was affected by thermal degradation.
Synthesis and copolymerization of macromonomers based on 2‐nonyl‐ and 2‐phenyl‐2‐oxazoline
Authors: Groß Aurelia , Maier Gerhard , Nuyken Oskar 
Published: April 2003

AbstractSeveral macromonomers were prepared by cationic ring‐opening polymerization of 2‐nonyl‐ and 2‐phenyl‐2‐oxazoline using different techniques of functionalization. Introduction of the unsaturated functional group directly via a suitable termination agent proved to be superior to the use of a phenol‐functionalized initiator and to the introduction of hydroxyl end groups via hydrolysis of the reactive cationic chain end and subsequent esterification with methacryloyl chloride. The macromonomers were characterized by spectroscopic techniques as well as GPC. One of the 4‐vinylbenzyl‐terminated macromonomers was copolymerized with MMA in different ratios. The copolymerization parameter r1 was determined to be 0.75. The resulting graft copolymers were characterized regarding number of grafts per chain, molar mass, and glass transition temperature.