bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aldehydes and acetals based on acryl‐ and methacrylamides as potential monomers
Authors: Zábranský Jiří , Houska Milan , Kálal Jaroslav 
Published: April 2003

AbstractHydrophilic monomers containing aldehyde or acetal groups based on N‐substituted amides of methacrylic and acrylic acid were prepared. The structure of these monomers prevents undesirable spontaneous intramolecular cyclization reactions of pendant aldehyde groups of the corresponding polymers. The following monomers were prepared: N‐(2‐formyl‐2‐methylpropyl)‐N‐methylmethacrylamide (3), N‐(2,2‐dimethoxyethyl)‐N‐methylmethacrylamide (5a), N‐(2,2‐dimethoxyethyl) methacrylamide (5b) and N‐(2,2‐dimethoxyethyl)‐N‐methylacrylamide (12).
Polymers with aldehyde and acetal groups based on esters of methacrylic acid
Authors: Zábranský Jiří , Houska Milan , Plichta Zdeněk , Kálal Jaroslav 
Published: April 2003

AbstractSoluble poly(2,2‐diethoxyethyl methacrylate) (1a) was prepared by radical polymerization in solution. Copolymers from 2,2‐diethoxyethyl methacrylate (3a), 2‐hydroxyethyl methacrylate (4) and ethylene dimethacrylate (5) were prepared by suspension polymerization in the form of crosslinked beads (50–220 μm in diameter, specific surface area up to 38 m2/g). Acetal groups of these polymers resist direct hydrolysis, but can be transacetalized. Soluble poly(3,3‐diethoxypropyl methacrylate) (1b) was prepared by radical polymerization in solution. Copolymers with 4 and 5 were prepared by suspension polymerization in the form of crosslinked beads (30 – 140 μm in diameter; specific surface area up to 46 m2). The polymers readily under go quantitative transcacetalization. Soluble poly(2‐formylethyl methacrylate) (8) was prepared by radical polymerization in solution. Copolymers of 2‐formylethyl methacrylate (7) with 4 and 5 were prepared by suspension polymerization in the bead form (diameter 75 – 350 μm; specific surface area up to 128 m2/g). The aldehyde group of these polymers is sensitive to oxidation in air. The content of aldehyde groups was measured spectrometrically and by reaction with 1,2‐ethanedithiol.
Polymers with aldehyde and acetal groups based on acryl‐ and methacrylamides
Authors: Zábranský Jiří , Houska Milan , Kálal Jaroslav 
Published: April 2003

AbstractA soluble hydrophilic polymer, poly[N‐(2,2‐dimethoxyethyl)methacrylamide] (4), and a crosslinked copolymer from N‐(2,2‐dimethoxyethyl)methacrylamide (3) and N,N′‐methylenediacrylamide (5) were prepared by radical polymerization in solution. Soluble hydrophilic poly[N‐(2,2‐dimethoxyethyl)‐N‐methacrylamide] (8) and the copolymer from N‐(2,2‐dimethoxyethyl)‐N‐methylacrylamide (7) and (5) were prepared by the same procedure. Acetal groups of these polymers can be hydrolyzed with HCl. N,N‐disubstituted methacrylamides, N(2‐formyl‐2‐methylpropyl)‐N‐methylmethacrylamide (2) and N‐(2,2‐dimethoxyethyl)‐N‐methylmethacrylamide (1) do not undergo radical homopolymerization.
Synthesis and characterization of bisacrylamide microgels containing sulfo groups
Authors: Huang Ying , Seitz Ulrich , Funke Werner 
Published: April 2003

AbstractReactive microgels containing sulfo groups were prepared by copolymerization of N,N′‐methylenediacrylamide (1) and 2‐acrylamido‐2‐methylpropanesulfonic acid (2) in water. The composition of the microgels, their structure, density, molecular weight and viscosity in solution were examined depending on the composition of the monomer mixture and the reaction conditions.
Oligoamide aus Dodecandisäure und 4,4′‐Methylendicyclohexylamin. (Oligoamide des „Qiana”︁‐Typs)
Authors: Hahn Günther Erhard , Kusch Peter , Rossbach Volker , Zahn Helmut 
Published: April 2003

AbstractThe pure isomers of cyclic monomers were synthesized besides the linear polymers by cyclocondensation reactions of dodecanedioyl dichloride and the pure isomers of 4,4′‐methylenedicyclohexylamine. The resulting cyclic amides were characterized by 1H NMR, IR and mass spectroscopy, as well as by HPLC and X‐ray diffraction. The content of these cyclic amides in “Qiana”‐Polyamide was determined by fractionated extraction and sublimation. Synthesis and properties of monomeric linear condensation product (dicarboxylic acid‐type with blocked and free end groups) are also described.
Dimethylsiloxane‐ethylene oxide block copolymers, 2. Preliminary results on dilute solution properties
Authors: Haesslin Hans‐W. 
Published: April 2003

AbstractThe dilute solution properties of poly(ethylene oxide)‐polydimethylsiloxane‐poly(ethylene oxide) (POE‐PDMS‐POE) triblock copolymers, of a POE‐PDMS segmented block copolymer and of a grafted PDMS‐g‐(POE‐co‐POP) copolymer are investigated by means of viscosity, light scattering and small angle neutron scattering. The experiments indicate that the copolymers are molecularly dispersed or aggregated, depending on the properties of the solvents. A rather compact conformation is deduced from the viscosity measurements. Negative A2‐values are observed in preferential solvents for one of the segments, a positiv A2‐value in a common solvent for both segments forming the block copolymer.
Polymerization of 1‐alkynes initiated by μ‐alkylidene complexes of tungsten, 2. Kinetics and mechanism of the initiation reaction
Authors: Meziane Driss , Soum Alain , Fontanille Michel , Rudler Henri 
Published: April 2003

AbstractThe existence of two successive and quite different stages in the polymerization of monosubstituted 1‐alkynes (1‐heptyne), initiated by a homo dinuclear μ‐alkylidene derivative of tungsten, is demonstrated. The first step leads to a mixture of species, the stability of which increases with the number of inserted monomeric units until inactivation. In order to explain the reactivation of these species in the second step, the loss of one carbonyl ligand is postulated, although no experimental evidence of that exists. The second step leads to high molecular weight polymer.
Polymerization of propene initiated with solubilized Ziegler‐Natta Li/Ti(III) based systems
Authors: Cansell François , Siove Alain , Fontanille Michel 
Published: April 2003

AbstractPolymer [ TiCl2, TiCl3, 3LiCl] complexes were used as solubilized Li/Ti(III) based initiators for Ziegler‐Natta polymerization of propene, leading to block copolymers. From measurements of the amount of diblock copolymers produced, a direct determination of the efficiency of the catalytic system was made. This efficiency was found to be equal to about 80% with respect to the number of potentially active centers. The activity of such systems was studied as a function of both initiator concentration and [monomer]0. From the measured values of activity and efficiency of the system, the rate constants of propagation were deduced. The kinetic behaviour of such a system is fully consistent with that of a living one. A first order kinetics towards both propene and active center concentration was found. Therefore, the rate constant of propagation is an absolute rate constant, measuring the intrinsic reactivity of active sites. GPC, 13C NMR and DSC analyses of the block copolymers permitted the establishment of their well‐defined linear diblock structure and disclosed a partial stereoregularity of the polypropene block (≈ 50% isotactic triads).
Free radical crosslinking copolymerization in the post‐gel state, 3. Swelling and mechanical properties of polystyrene networks
Authors: Hild Gérard , Okasha Rouzi , Rempp Paul 
Published: April 2003

AbstractThe free radical crosslinking copolymerization of styrene with a bi‐unsaturated comonomer (divinylbenzene, ethylene dimethacrylate), present in small proportions, yields three‐dimensional polymer networks. The gelation time tc is generally longer than expected if all double bonds originating from the bi‐unsaturated monomer (including the pendent double bonds) were isoreactive. This delay in gelation has been attributed to the formation of intramolecular cyclizations, or to the lower reactivity of the pendent double bonds with respect to growing radicals. This paper, devoted to an investigation of the network forming reaction after gelation, presents some additional evidences in favor of the latter assumption, resulting from the variation of the fraction of extractable polymer, of the swelling degree and of the modulus of the swollen networks as a function of the overall degree of conversion. Furthermore, a direct proof of the role of the pendent double bonds is given by the “two‐step” crosslinking experiments carried out.
Dielectric relaxation in solid dextran and pullulan
Authors: Katsuyoshi‐Nishinari  , Shibuya Naoto , Kainuma Keiji 
Published: April 2003

AbstractThe temperature dependences of the dielectric constants of solid dextran and pullulan were observed at 10 Hz for various moisture levels of the polysaccharides. Because the dielectric loss peak at about −50°C, observed both in dextran and pullulan, shifted to higher temperatures and decreased its intensity with decreasing the moisture level, this peak was considered to be caused by water molecules. The peak at about −90°C for pullulan was attributed to the rotational motion of hydroxymethyl groups, while the peak at about −120°C for dextran was attributed to the libration of glucose residues around the α‐1,6 linkage. In order to examine this lower temperature process, the frequency dependence was observed in the temperature range from −110°C to −60°C.
Soluble cyclopentadienylated polymers
Authors: Miura Masatoshi , Akutsu Fumihiko , Usui Toshio , Ikebukuro Yasuhiro , Nagakubo Kuniharu 
Published: April 2003

AbstractCopolymers from styrene and a mixture of p‐ and m‐chloromethylstyrene were reacted with sodium cyclopentadienide in THF and precipitated in methanol at temperatures lower than −20°C to obtain soluble cyclopentadienylated polymers. Due to extensive gelation, the content of cyclopentadienyl groups could not be increased to more than 4 mol‐% except with extremely low molecular weight polymers. An improved method, in which the copolymer was cyclopentadienylated in the presence of metallic sodium, gave soluble polymers with up to 29 mol‐% cyclopentadienyl groups. Pendant cyclopentadienyl groups undergo Diels‐Alder/retro‐Diels‐Alder addition to give thermoreversible cross‐linked polymers. The amount of gel fraction of a 4 mol‐% cyclopentadienylated polymer as a function of the heating time was examined in the temperature range of 40–80°C. The DSC curve of a 29 mol‐% cyclopentadienylated polymer showed an exothermic peak due to the Diels‐Alder reaction and an endothermic peak starting around 390°C, a temperature higher than that found for the degradation of polystyrene.
Iodine‐poly(vinyl alcohol) interactions, 2. Anomalous slow quenching of the chromophore after extraction of free iodine with carbon tetrachloride
Authors: Yokota Toshio , Kimura Yoshiharu 
Published: April 2003

AbstractAn equilibrium blue colored solution containing poly(vinyl alcohol) (PVA)‐iodine‐boric acid was prepared at 5°C. With increasing PVA concentration, at the same concentration of iodine, the absorption band of the chromophore I (λmax = 650 nm, band D) linearly increased and the intensities of the bands for both I− (λmax = 226 nm, band A) and I (λmax = 290 nm, band B) decreased. The band due to another iodide species (λmax = 355 nm, band C), tentatively assigned to I · I2, remained unchanged. Three solutions with different PVA concentration were then extracted with the same volume of carbon tetrachloride to remove I2 present in the system. It was found that the chomophore due to I gradually decays with repeated extractions. After one extraction the change of the absorbance of I with time was measured at 5°C. In the system with a high PVA concentration the chromophore recovers the equilibrium within three days without losing much intensity, while in the systems with lower PVA concentration recovering of equilibrium takes more than four days with a considerable loss of chromophore. In the latter case, free I2 extracted is supplied by the decomposition of polyiodide ions to I−. Analysis of the rate of re‐equilibration of iodine species revealed two reaction processes: one is a reaction involving free iodine species in an aqueous environment and the other is a slow reaction involving the polyiodide ions bound in a PVA cage.
Phase transitions in polyphosphazene films: Poly[bis(trifluoroethoxy)phosphazene]
Authors: Kojima Morio , Magill Joseph H. 
Published: April 2003

AbstractThe morphology of cast and annealed films from poly[bis(trifluoroethoxy)phosphazene] \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \{ PBFP,\rlap{--} [(CF}_{\rm 3} {\rm CH}_{\rm 2} {\rm O)}_{\rm 2} {\rm P = N\rlap{--} ]}_{\rm n} {\rm \} } $\end{document} has been studied by electron, scanning electron and optical microscopy. Several polymorphic forms and one mesophase (hexatic) have been established. From THF solution, PBFP has a chain folded morphology (α‐orthorhombic) which transforms into a chain extended 2D hexagonal mesophase at T(1). It remains in this state until final melting occurs at Tm = 245°C approximately. Upon cooling the melt, it quickly reverts to the hexagonal mesophase again, but then passes into a chain extended (3D) γ‐orthorhombic modification. This material is much more stable thermodynamically than the α‐form, which is friable or brittle. PBFP cannot be quenched to a glassy form from the molten state, but it can be disordered as assessed by its reduced T(1) enthalpy and less well defined morphology assessed by electron microscopy. Another crystal modification (β‐monoclinic) has been found in solution cast low molecular weight PBFP films.
Spin probe study of relaxation in poly(oxytetramethylene)
Authors: Lembicz Franciszek 
Published: April 2003

AbstractUsing the spin probe method, the rotational mobility of two probes in poly(oxytetramethylene) (POT) in the region of rapid and slow rotation was investigated. Based on the relaxation diagram the obtained ESR results are compared and discussed in connection with other literature data. It was found that the behaviour of the probes corresponds to the α + β relaxation in the range of high frequencies. Differences in mobility of the probes as well as anisotropy effects of rotations are also discussed.
The chemical dehydrochlorination of poly(vinyl chloride), 2. Studies on N,N‐dimethylformamide solutions
Authors: Bowley Heather J. , Gerrard Donald L. , Maddams William F. 
Published: April 2003

AbstractThe chemical dehydrochlorination of poly(vinyl chloride) was studied in solution in N,N‐dimethylformamide. By comparison with solutions in tetrahydrofuran, examined previously, the reaction was found to occur at a significantly enhanced rate for the four systems studied, a mass polymer of 55% syndiotacticity and a low temperature polymer of 63% syndiotacticity, dehydrochlorinated with potassium hydroxide or with potassium tert‐butoxide. Furthermore, at dehydrochlorination levels up to about 60%, markedly longer polyene sequences are formed, the more so in the case of potassium tert‐butoxide., where they reach values of at least 65, as assessed by Raman spectroscopy. For levels of 80%, and greater, there is a significant decrease in the sequence lengths, the result of cross‐linking, which is facilitated by the substantial loss of the \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} ({\rm CHCl \hbox{---} CH}_{\rm 2} \rlap{--} )_n$\end{document} sequences that sterically protect the long polyenes in the les heavily dehydrochlorinated materials. Limited results are also presented for chemically dehydrochlorinated PVC prepared by the urea clathrate method; the insolubility of this polymer probably leads to degradation on the surface of the particles only.
A polymeric prodrug of quinidine for controlled and programmed release
Authors: Astinotti Daniel , Lapicque Françoise , Dellacherie Edith 
Published: April 2003

AbstractA macromolecular prodrug of quinidine was synthesized by linking the amino ester of L‐phenylalanine with quinidine to carboxymethylcellulose via an amide bond. The release of the drug results from the hydrolysis of the ester linkage which occurs only in the presence of α‐chymotrypsin at pH 8. This specificity is relative to the nature of the ester derivative whose carboxylic moiety is an aromatic amino acid residue with L‐configuration. This prodrug contains 160 mg of quinidine per g of dry powder and allows a prolonged release (5–7 h) of the drug in an intestinal medium.
Etude des propriétés électro‐optiques de l'ADN par biréfringence électrique à faible champ, 4. Influence des interactions ADN‐histones
Authors: Marion Christian , Roux Bernard 
Published: April 2003

AbstractThe interactions of DNA with histone complexes (H2A, H2B, H3, H4) were studied by lowfield electric birefringence measurements. Electro‐optical measurements revealed that histones induce a folding of the DNA molecules: with increasing ratio histones/DNA, the steady‐state birefringence and the orientational relaxation time decrease gradually. A contribution of a permanent dipole moment to the orientation mechanism appears, while the electrical polarizability decreases quickly without significant differences in the optical anisotropy factors.
Poly(Ferulic acid) by thionyl chloride activated polycondensation
Authors: Elias Hans‐Georg , Palacios Joaquin A. 
Published: April 2003

AbstractFerulic acid (= 4‐hydroxy‐3‐methoxycinnamic acid) was condensation polymerized at temperatures between 0 and 50°C in bulk or various solvents, using thionyl chloride as activator in the presence or absence of bases. Depending on reaction conditions, true relative yields up to 100% and reduced viscosities (at 0,005 g/mL solute concentration) up to 96 mL/g were observed. The polycondensation follows a 2‐stage kinetics.
Effect of thermodynamic strength of solvent on structure formation of crosslinked copolymers
Authors: Krakovyak Mark , Ananieva Tatiana , Anufrieva Elisaveta , Nekrasova Tatiana , Sinitsina Galina 
Published: April 2003

AbstractThe effect of the thermodynamic strength of the solvent used in the copolymerization of mono‐ and bifunctional monomers on the molecular‐topologic structure of soluble copolymers with bridge bonds was investigated. The investigation was carried out taking as an example radical copolymerization of methyl methacrylate (MMA) and 9,10‐anthrylenedimethyl dimethacrylate. The presence of anthracene groups in the molecules of the crosslinking agent made it possible to follow the number of intra‐ and interchain bridge bonds formed in the polymer system. Toluene/octane mixtures with an octane content from 0 to 35 vol.‐% were used as solvents of different thermodynamic strengths with respect to PMMA. It was found that over a narrow range of changes in the composition of the solvent (from 30 to 33 vol.‐% of octane) the values of M̄n and [η] of the copolymers increase drastically. It is shown that this increase is due to an increase in the number of interchain crosslinks occurring when the strength of the solvent under the copolymerization conditions used decreases.
Large deformation of hydrogels of poly(vinyl alcohol), agarose and kappa‐carrageenan
Authors: Watase Mineo , Nishinari Katsuyoshi 
Published: April 2003

AbstractThe deformation behaviour of hydrogels of poly(vinyl alcohol) (PVA), agarose and kappa‐carrageenan was investigated and compared with each other. PVA gels prepared by periodically repeated freezing‐thawing cycles showed a much larger breaking force and breaking deformation than agarose and kappa‐carrageenan gels.
Photo‐sensitized oxidation of styrene‐butadiene copolymer. Role of singlet oxygen
Authors: Nowakowska Maria 
Published: April 2003

AbstractThe potosensibilization effect of anthracene and its substituted derivatives on the oxidation of styrene‐butadiene copolymer (SBR) was investigated. The potosensitized oxidation of SBR is explained on the basis of a reaction between singlet oxygen and the copolymer.
Studies on electrochemically prepared oxidized polypyrrole salt films
Authors: Bi Xiangtong , Yao Youxin , Wan Meixiang , Wang Ping , Xiao Ke , Yang Qiyung , Qian Renyuan 
Published: April 2003

AbstractIt was found that oxidized polypyrrole (PPy) film, electrochemically polymerized from aqueous H2SO4 solutions, shows correct stoichiometry in the mole ratio C : H : N, although still containing a large amount of oxygen. The apparent density of the film obtained was close to its flotation density of 1,514 g/cm3. Morphology studies by SEM showed an aggregation of ca. 1 μm properties into hollow bowls of 30 μm diameter in the case of PPy‐BF4, PPy‐PF6 and PPy‐CIO4 films, electrochemically prepared from CH3CN (1% H2O) solutions, while a PPy‐HSO4 film from aqueous solution gave a much smoother film surface and no hollow bowls. Interesting morphology was observed for the growth of electrochemically oxidized PPy in CH3CN solution on a wire net anode of 27 × 27 μm2 holes. The nucleation of the oxidized PPy growth was found to be always initiated at the mid‐points of the four sides of the square holes so that regular arrays of hollow bowls resulted. In aqueous H2SO4 solution the oxidized PPy grew on the surface of the net wires. Besides particles of ca. 0,3 μm diameter numerous solid blocks of 5 μm size with sharp edges were observed. The metallic temperature dependence of the conductivity of various oxidized PPy films was demonstrated by voltage shorted compaction (VSC) measurements, while a partially electrochemically reduced PPy‐BF4 film showed a broad maximum in VSC conductivity around 100 K.
Heat capacity of semicrystalline, linear poly(oxymethylene) and poly(oxyethylene)
Authors: Suzuki Hidematsu , Grebowicz Janusz , Wunderlich Bernhard 
Published: April 2003

AbstractThe heat capacities of 38 semicrystalline poly(oxymethylene)s and poly(oxyethylene)s were determined by differential scanning calorimetry from 205 K through the melting transition. By comparison with the well known limiting heat capacities of the supercooled liquids and the crystals of the macromolecules it was found that there are negative and positive deviations from additivity of the heat capacities with crystallinity between the glass transition and the melting transition. The negative deviations are linked with “rigid amorphous” material, and the positive deviations were previously linked to defect formation or early melting. The rigid amorphous fraction in poly(oxymethylene) is constant up to the melting region, in contrast to polypropylene, where it is decreasing with temperature. The proposed mesophase transition in poly(oxymethylene) is shown to be a minor effect. The poly(oxyethylene) heat capacity is governed by positive heat capacity deviations within the rather short temperature range between glass transition and melting.
Structure determination by two‐dimensional NMR of α‐hydro‐ω‐butyloligostyrenes fractionated by liquid chromatography
Authors: Ray G. Joseph , Pauls Richard E. , Lewis Jerry J. , Rogers Lockhart B. 
Published: April 2003

AbstractTwo aspects of the reversed‐phase liquid chromatographic separation of α‐hydro‐ω‐butyloligostyrene stereoisomers are presented. In the first part, two‐dimensional NMR is employed to make stereochemical assignments on isolated dimer, trimer and tetramer species. This work established the elution pattern of the stereoisomers as isotactic, heterotactic and syndiotactic for tetramers. In the second part, the elution behavior of these stereoisomers in reversed‐phase chromatography is compared to that observed in size exclusion chromatography, and these comparisons suggest that differences in the effective sizes of the stereoisomers are important factors in their separation.
Water‐insoluble polyacrylamide, 1. Syntheses and characterization of polymers from acryloylaminobenzoic acids
Authors: Patel Kishore , Desai Trushar , Suthar Bhikhu 
Published: April 2003

Abstract2‐, 3‐ and 4‐Acryloylaminobenzoic acids were prepared in overall yields of 72, 78 and 83%, respectively. Radical polymerizations of all three monomers were studied using 2,2′‐azoisobutyronitrile as initiator in 1,4‐dioxane at three different temperatures. The unfractionated polymers were characterized by their physical properties, IR and NMR spectral studies, viscosity measurements and vapour pressure osmometry. The thermal properties were elucidated by thermogravimetry.