bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acylation of hydroxyl groups in polymers with carbonic acid derivatives in the presence of tertiary amines
Authors: Boeden Hans‐Friedrich , Büttner Werner , Rupprich Christian , Büttner Dorothea , Heinrich Sigrun , Becker Manfred , Holtzhauer Martin 
Published: April 2003

AbstractSymmetrical carbonates were formed when the corresponding carbonochloridates containing electron‐withdrawing groups were converted with tertiary amines in dry solvents at room temperature. 5‐Norbornene‐2,3‐dicarboximido carbonochloridate (1) and bis(5‐norbornene‐2,3‐dicarboximido) carbonate (5) were used for acylation of OH groups in polymers in the presence of tertiary amines under anhydrous conditions. The influence of the amounts of 1 and 5, the kind and amount of amines, the organic solvent, the reaction time and temperature on the yield of the active carbonate 7 was investigated using bead cellulose as polymer. The reaction based on the catalysis by strongly nucleophilic amines such as 4‐dimethylaminopyridine (DMAP) was optimized for preparation of acylated polymers. The formation of cross‐linking and cyclic carbonates 9 and 10, respectively, was observed as a side reaction. It was shown that carbonates 9 and 10 can also be obtained as the main products of acylation. The preparation of 9 was also carried out by treating 7 with an excess of DMAP. Examples are presented for the transesterification of 7 with compounds containing OH groups. The acylated polymers were characterized by a specific titration method, UV/VIS and IR spectroscopy. The mechanism of the DMAP‐catalyzed acylation of polymers is discussed.
The higher homologues of triphenylamine: Model compounds for poly(N‐phenyl‐1,4‐phenyleneamine)
Authors: Strohriegl Peter , Jesberger Gabrile , Heinze Jürgen , Moll Thomas 
Published: April 2003

AbstractWell‐defined model compounds of poly(N‐phenyl‐1,4‐phenleneamine)(2), the dimer5, the trimer6and the tetramer7, were prepared by stepwise synthesis. Cyclic voltametry and the mass spectra demonstrate the high stability of the radical cations from the model compounds. The UV spectra show that there is some conjugation through the lone electron pair at the nitrogen atom, but the amount of conjugation is rather small. Oligo(N‐phenyl‐1,4‐phenyleneamine)(2)with an average degree of polymerization of 10 was prepared by metalation ofN,N′‐diphenyl‐1,4‐phenylenediamine and subsequent reaction with 1,4‐diiodobenzene.
Enhanced electrochromic stability of polyaniline in polyaniline‐matrix polymer composite films in aprotic medium
Authors: Morita Mitsuyuki , Hashida Isao 
Published: April 2003

AbstractElectrochromic behavior and stability in aprotic medium of polyaniline composite films prepared by chemical oxidative polymerization at gas/liquid interface were investigated. The results are compared with chemically and electrochemically snythesized polyaniline homogeneous films. The polyaniline composite films show almost the same electrochromic behavior as the homogeneous films. The behavior is due to a two‐step oxidation mechanism, which is different from that in aqueous medium, especially in the second oxidation process. Degradation of polyaniline in aprotic medium is due to the partial formation of the electrochemically inactive quinonediimine structure in the higher oxidized state. The degradation is restrained by hybridization with an appropriate matrix polymer. The stabilization of the electrochromic behavior of polyaniline depends on molecular weight and pKa of the matrix polymer.
Synthesis of a new family of poly(amido‐amine)s carrying poly(oxyethylene) side chains
Authors: Vansteenkiste Stefan , Schacht Etienne , Ranucci Elisabetta , Ferruti Paolo 
Published: April 2003

AbstractA new class of water‐soluble poly(amido‐amine)s (PAA's) carrying poly(oxyethylene) (PEO) side chains were synthesized following two distinct pathways. The first route consists in the direct stepgrowth polymerization through addition in water of an equimolar amount of α‐(2‐aminoethyl)‐ω‐methoxypoly(oxyethylene) (6) of well‐defined molecular weight to 1,4‐bis(acryloyl)‐piperazine (7). Furthermore, this reaction was performed in the presence of an excess of the bisacrylmonomer 7, resulting in a new bisacrylic macromonomer (9) of PEO. In the second route this bisadduc 9 was then polymerized with piperazine (10), yielding a PEO‐grafted PAA. The structures of both polymers were characterized by means of 1H NMR. Viscosity and vapour pressure osmometric measurements revealed that the molecular weights in both cases were fairly low (M̄n ≈ 3 000).
Copolymerization of epoxides and five‐membered cyclic carbonates in the presence of zinc coordination catalysts
Authors: Kuran Witold , Listoś Tomasz 
Published: April 2003

AbstractAlkylene oxides like ethylene oxide (1a) and propylene oxide (1b) were reacted with alkylene carbonates like ethylene carbonate (2a) and propylene carbonate (2b) in the presence of catalysts based on diethylzine and polyphenols (pyrogallol, 4‐tert‐butylcatechin) and catalysts based on diethylzinc‐phenol at temperatures in the range of 35–100°C. Reaction products were characterized by means of elemental analysis, IR, 1H NMR and 13C NMR spectroscopy and molecular weight determinations. The products appeared to be the respective low‐molecular‐weight copolymers – poly[oxyalkylene‐co‐(alkylene carbonate)]s: poly[oxyethylene‐co‐(ethylene carbonate)] (3 aa), poly[oxyethylene‐co‐(propylene carbonate)] (3 ab), poly[oxypropylene‐co‐(ethylene carbonate)] (3 ba) and poly[oxypropylene‐co‐(propylene carbonate)] (3 bb). Copolymers obtained with diethylzinc‐polyphenol catalysts were of higher molecular weight than those obtained with diethylzinc‐phenol catalysts. They contained more than 50 mol‐% of alkylene oxide units. Predominant head‐to‐tail arrangement of these units including those connected via carbonate linkages was observed by means of NMR spectroscopy in the case of 3 bb.
Viscometric characterization of poly(oxyethylene)‐block‐poly(oxypropylene)‐block‐poly(oxyethylene) in aqueous solution
Authors: Bloß Peter , Hergeth Wolf‐Dieter , Wohlfarth Christian , Wartewig Siegfried 
Published: April 2003

AbstractViscometric measurements were carried out to characterize poly(oxyethylene)‐block‐poly‐(oxypropy1ene)‐block‐poly(oxyethy1ene) (POE‐POP‐POE) in aqueous solution. The results were discussed in terms of a core‐shell model of intramolecular phase separation which is based on (i) the selectivity of the solvent water, and (ii) the incompatibility of the POE and POP blocks. The interaction between the two blocks was analysed by vapour pressure osmometry and vapour sorption investigations.The results are:The two homopolymer blocks (POE and POP) forming the triblock copolymer are incompatible with each other as vapour pressure osmometry and vapour sorption measurements using ethylbenzene as solvent have shown. This incompatibility of the blocks as well as the selectivity of the solvent water with respect to the different blocks causes the intramolecular (and intermolecular) phase separation of the copolymers in aqueous solution.The viscometric data of the aqueous block copolymer solutions can be discussed in terms of the generally accepted core‐shell model. This model for the structure of the self‐organized molecules includes POP gel core (“melt”) surrounded by solvated POE shell. A quantitative analysis according to this simplified view shows that the hydrodynamic volume of the copolymer molecules is determined by the POE blocks. In the temperature range ϑ > 30°C, the influence of the POP block on the molecular dimensions is negligible, whereas at ϑ < 30°C the contributions of the POP and POE to the molecular volume are comparable.Kuhn's statistical segment length of POE in the triblock molecules comprises about 4–5 monomeric units. The theta temperature of the triblock copolymer molecules is nearly identical to that of pure POE ((369 ± 3)K).
Utilisation de l'analyse viscoélastique dynamique à l'étude de la cristallisation isotherme du poly(téréphtalate d'ethylène) amorphe. Application à des composites unidirectionnels avec fibres de verre
Authors: Gauthier Catherine , Chailan Jean‐François , Chauchard Jacques 
Published: April 2003

AbstractDynamic viscoelastic analysis was used to continuously follow the “cold crystallisation” of poly(ethylene terephthalate) (PET) test bars. Samples which were cut from an amorphous PET sheet were heated to a given temperature in a hot cell. The evolution of the real part of the modulus not only allows the kinetic crystallisation parameters but also the nucleation and growth characteristics to be determined. This method was applied to unidirectional PET/glass fibre composite strips. Thus, the influence of the glass fibres on the morphological and kinetic characteristics of the matrix crystallisation has been investigated.
Magnesium stearate based titanium catalyst systems for propene polymerization
Authors: Gupta Virendra Kumar 
Published: April 2003

AbstractSupported titanium catalysts are prepared by chlorination of magnesium stearate with silicon tetrachloride (Mg, Ti‐S) or titanium tetrachloride (Mg, Ti‐T) followed by treatment of the product with diisobutyl phthalate and titanium tetrachloride. The data indicate that the change in the nature of the chlorinating compound affects the composition as well as physical characteristics of the catalysts. The results of propene polymerization show that the Mg, Ti‐T/AlEt3 catalyst system has about 50% more productivity and higher isospecificity as compared to the Mg, Ti‐S/AlEt3 system. Furthermore, the isospecificity of the Mg, Ti‐T/AlEt3 system is independent of polymerization time, whereas the Mg, Ti‐S/AlEt3 system shows a change of isospecificity with time. Addition of an external Lewis base and cocatalyst [triethoxy(phenyl)silane with triethyl‐aluminium] to the Mg, Ti‐T catalyst substantially improves the isospecificity of the system.
Terpolymer relationships and ternary azeotropes
Authors: Ham George E. 
Published: April 2003

AbstractA paper by Quella which appeared in this journal (Makromol. Chem. 190, 1445 (1989)) criticized a 1983 publication by this author. Quella has suggested that my paper postulating the non‐existence of ternary azeotropes “is contradicted on the basis of mathematical solutions and further experimental results from other authors.” The present paper is in response to Quella.
Addition of oxiranes to the acids of phosphorus. Direction of ring opening
Authors: Biela Tadeusz , Kubisa Przemyslaw , Penczek Stanislaw 
Published: April 2003

AbstractThe proportion of the α‐ and β‐ring opening in the addition of unsymmetrically substituted oxiranes to POH acids namely diethyl phosphoric acid, phosphorous acid, and phosphoric acid, was established. Ring opening of propylene oxide does not depend on the number of the POH groups in the acid and, for di‐ and trifunctional acids, does not depend on the degree of substitution. After this first reaction of addition the formed hydroxyl groups add the oxirane molecules and the phosphorus‐containing polyethers are formed. All of the propylene oxide additions exhibit a ratio of α/β‐ring openings of 1:1. For the higher substituted oxiranes the proportion of the attack on the least substituted carbon atom increases, reaching for 1,1‐dimethyloxirane up to 90% of α‐addition (almost exclusive formation of the tertiary alcohol).
Emulsion copolymerization of vinyl chloride with butyl acrylate
Authors: Capek Ignac , Mrázek Zdenek 
Published: April 2003

AbstractThe emulsion copolymerization of vinyl chloride and butyl acrylate initiated by ammonium peroxodisulfate at 60°C in the presence of an anionic emulsifier was investigated. Random copolymers of butyl acrylate and vinyl chloride covering several sets of monomer compositions were synthesized by emulsion copolymerization conducted to both low and high conversions. The rate of butyl acrylate polymerization at medium conversion was found to be proportional to the 0,5 and 1,0 power of the butyl acrylate concentration for the system with and without vinyl chloride. The overall rate of poymerization was found to decrease with increasing vinyl chloride concentration in the monomer feed. The particle size increases with increasing vinyl chloride monomer concentration in the monomer feed and conversion. The decrease in molecular weight of butyl acrylate/vinyl chloride copolymer is accompanied with the incease of vinyl chloride concentration in the monomer feed and of conversion. The results are discussed in terms of radical desorption, particle nucleation and the dependence of the equilibrium monomer concentration on the reactor pressure.
Electric characteristics of polycation perchlorate composites as a solid electrolyte and its application
Authors: Ishizawa Ryosyo , Seki Miharu , Kadoi Kiyoaki , Yosomiya Ryutoku 
Published: April 2003

AbstractPolycation perchlorate composites have excellent film‐forming properties and high ionic conductivity. The ionic conductivity at 40°C is of the order of 10−7−10−5S·cm−1, depending on the kind of perchlorate. The temperature dependence of the ionic conductivity follows the Williams‐Landel‐Ferry relationship. Furthermore, the electrochemical polymerization of pyrrole using polycation perchlorate composites as a solid electrolyte produces bilayer composite films.
Styrene polymerization in oil‐in‐water microemulsions: kinetics of polymerization
Authors: Gan L. M. , Chew C. H. , Lye I. 
Published: April 2003

AbstractMicroemulsion polymerization of styrene was carried out in water, hexadecyltrimethylammonium bromide or sodium dodecyl sulfate, and butyl carbitol (system. name: 2‐(2‐butoxyethoxy)ethanol) using water‐soluble potassium peroxodisulfate (KPS) or oil‐soluble 2,2′‐azoisobutyronitrile (AIBN) as initiator. The latexes have been stable for one year. The effects of temperature, initiator and monomer concentrations on the polymerization kinetics were investigated. The polymerization rates were measured by dilatometry and show two stages (nucleation and growth). A longer nucleation period was found in the polymerization initiated by KPS as compared to AIBN. The initial polymerization rate varied with the 0,47 power of KPS concentration and the 0,39 power of AIBN concentration. The activation energy of the polymerization was found to be relatively low (ca. 50 kJ/mol) for the system initiated with AIBN and about 90 kJ/mol for the KPS‐initiated system. Molecular weights of polystyrene of several millions were obtained in all cases, especially for systems initiated with AIBN. The latex particles were nearly spherical with an average particle diameter of about 25 nm. The mechanism of polymerization in the oil‐in‐water microemulsion is discussed.
Synthesis and properties of water‐soluble polyphosphazenes with aminoalcoholic functions
Authors: Crommen Jan H. L. , Vandorpe Joke , Schacht Etienne H. 
Published: April 2003

AbstractPhosphazene polymers with 2‐(trimethylsiloxy)ethylamino, 3‐(trimethylsiloxy)propylamino and 2,3‐bis(trimethylsiloxy)propylamino substituents are described. These polymers have been prepared by reaction of the corresponding hydroxy‐protected aminoalcohol with poly(dichlorophosphazene). Total halogen replacement was achieved only with the 2‐(trimethylsiloxy)ethylamino and 3‐(trimethylsiloxy)propylamino groups. Replacement of remaining chlorine was achieved by subsequent introduction of glycine ethyl ester groups as co‐substituents. The trimethyl silyl‐protecting groups were removed by reaction of the polymer with tetrabutylammonium fluoride. This yielded water‐soluble degradable polyphosphazene derivatives with 2‐(hydroxyethyl)amino, 3‐(hydroxypropyl)amino or 2,3‐(dihydroxypropyl)amino substituents. The structures and physical properties of the prepared polymers were investigated using NMR, IR, and thermal analyses. The hydrolytical degradation of the final water‐soluble polymers was also evaluated. A significant reduction in reduced viscosity and the release of 3‐amino‐1‐propanol was observed during incubation in water at 37°C of the polyphosphazene derivative substituted with 3‐(hydroxypropyl)amino groups.
High‐molecular‐weight polyethylene: growth reactions at bis(dichloroaluminium)ethane and trialkylaluminium
Authors: Martin Heinz , Bretinger Helmut 
Published: April 2003

AbstractWhen the temperature of the reaction of 1,1‐bis(dichloroaluminium)ethane or trialkylaluminium with ethylene is reduced to room temperature, polyethylenes with a largely linear structure having molecular weights between 300 000 and 9300 000 are produced. The stepwise addition of trialkylaluminium to ethylene then leads to highly crystalline products having melting ranges around 140°C. The reaction is no longer accompanied by the displacement reaction forming a‐olefins.
Effect of the alkyl residues on the glass transition temperature of methacrylonitrile/alkyl methacrylate copolymers
Authors: Román Julio San , Vázquez Blanca , Valero Miguel , Guzmán Gonzalo Martín 
Published: April 2003

AbstractThe glass transition temperature of copolymers of methacrylonitrile with methyl, ethyl and butyl esters of methacrylic acid, together with those of the corresponding homopolymers, were determined by differential scanning calorimetry. The variation of the glass transition temperature (Tg) of copolymers with the composition of the samples was analyzed for each system on the basis of treatments suggested by Barton, Johnston and Suzuki‐Mathot, determining the values of the glass transition temperature of the alternating diad (Tg12). It was observed in all the cases that the alternating diad presents a flexibility higher than that expected from the combination of both kinds of monomeric units according to the Tg of the corresponding homopolymers and that the Tg12 values decrease with the length of the side chain of the methacrylate ester in the system, as the Tg values of the polymethacrylates.
Synthèse de polystyrènes chlorométhylés renfermant de nouveaux groupements tétrathiafulvalénylcarbonyloxyméthyles
Authors: Mora Henri , Fabre Jean‐Marc , Giral Louis , Montginoul Claude , Sagnes René , Schué François 
Published: April 2003

AbstractIn order to conserve high contrast while improving the sensitivity of microlithographic resins made up of polystyrene bearing tetrathiafulvalene (TTF) units, we prepared new polystyrenes containing tetrathiafulvalenylcarbonyloxymethyl groups which are methylated or non‐methylated. The polymers were synthesized by reaction of poly[styrene‐co‐(p‐chloromethyl‐styrene)] with the corresponding caesium tetrathiafulvalenecarboxylate. To optimize this grafting reaction, preliminary reactions were carried out with model molecules.
Crystal structure of the form I of syndiotactic poly(1‐butene)
Authors: De Rosa Claudio , Venditto Vincenzo , Guerra Gaetano , Corradini Paolo 
Published: April 2003

AbstractThe crystal structure of the form I of syndiotactic poly(1‐butene) is presented. According to the present analysis, chains having s(2/1)2 helical conformation are packed in an orthorhombic unit cell with a = 16,81 Å, b = 6,06 Å and c = 7,73 Å. The density is 0,96 g/cm3 with two chains in the cell (8 monomeric units), the space group is C2221. Disorder, corresponding to the statistical presence of right‐ and left‐handed helices in each site of the lattice, could be present. The space group for the completely disordered structure is Cmcm.
Copolymerization reactivities and electron structure of 2‐alkyl‐5‐vinyltetrazoles
Authors: Ivashkevich Oleg A. , Gaponik Pavel. N. , Kovalyova Tamara B. , Makarevich Nonna I. , Sushko Natalia I. 
Published: April 2003

AbstractThree novel monomers: 2‐ethyl‐, 2‐isopropyl‐ and 2‐tert‐butyl‐5‐vinyltetrazole were synthesized. The copolymerizations of these monomers and 2‐methyl‐5‐vinyltetrazole with styrene and methyl methacrylate were examined and the corresponding reactivity ratios r1, r2 and the Alfrey‐Price Q, e values estimated. The obtained results, together with IR, 1H NMR and 13C NMR data and quantum‐chemical calculations of vinyltetrazole molecules by the AM‐1 method, indicate that the type and the size of the substituent does not essentially influence the reactivity of 2‐alkyl‐5‐vinyltetrazoles in radical copolymerization with vinyl monomers.
Synthesis and characterization of amphiphilic and microphase‐separated graft copolymers, 1. Synthesis and bulk characterization of polystyrene‐graft‐ω‐stearyl‐poly(ethylene oxide)
Authors: Qiu Yongxing , Yu Xiaojie , Feng Linxian , Yang Shilin 
Published: April 2003

AbstractUsing the rigid and hydrophobic polystyrene (PS) chain as backbone, onto which flexible and hydrophilic stearyl‐poly(ethylene oxide) (SPEO) chains are grafted, a new kind of amphiphilic, microphase‐separated graft copolymer was synthesized using the macromonomer technique. Stearyl‐poly(ethylene oxide) macromonomers with acryloyl end‐group (SPEO‐A) were prepared through an end‐group exchange reaction of α‐stearyl‐ω‐hydroxypoly(ethylene oxide) (SPEO‐OH) and acryloyl chloride in the presence of triethylamine. The radical copolymerization of styrene with SPEO‐A was carried out under various experimental conditions. Following a careful examination of their purity, the structure of the prepared copolymers was characterized by means of IR, 1H NMR and GPC analyses. A new feasible method using first derivative UV spectrometry was developed for quantitative determination of the bulk composition of the graft copolymers. Copolymers with a wide range of bulk composition and satisfactory grafting degree were obtained.
Synthese von nitrogruppenhaltigen copolymeren durch radikalische copolymerisation
Authors: Tauer Klaus , Wedel Armin , Morozova Elena M. 
Published: April 2003

AbstractRadical copolymerization of a nitro group containing azo‐dye monomer (1) and methyl methacrylate leads to significantly higher polymerization rates and higher molecular weights when dispersion technique is used instead of solution polymerization. The preparation of mechanically stable coatings and free films with good mechanical properties and transparency for electro‐optical investigations is possible by a spin coating technique with the dispersion copolymers. The dye side chains of these copolymers can be poled in an electric field. The orientation of the side chains leads to a change of the light absorption in the dye absorption band. Results of m‐line spectroscopy show that the copolymers possess wave guiding properties.
External silane donors in Ziegler‐Natta catalysis. Computerbased molecular model calculations on alkoxysilanes
Authors: Härkönen Mika , Kuutti Lauri , Seppälä Jukka V. 
Published: April 2003

AbstractThe electronic factors of external alkoxysilane donors used in modern Ziegler‐Natta catalyst systems were estimated by quantum mechanical MNDO (modified neglect of diatomic overlap) calculations on model compounds. The calculated electron densities of oxygen atoms in alkoxy groups were plotted against the experimental activity and the isotacticity of propene polymerization. The steric hindrance and the volume of the compounds were investigated as structural factors important to the polymerization. The results indicate that the performance of the external alkoxysilane donor is affected by both electronic and structural factors. The average electron density around the electron‐donating oxygens has some influence on the deactivating power of the donor, but when the hydrocarbon part is sterically large the sterical effects apparently dominate.