bluuebunny/crossref_metadata_2025 huggingface dataset:
Etude morphologique de bloc‐copoly(éther‐amide)s
Authors: Xie Ming , Camberlin Yves
Published: April 2003

A series of ether‐amide block copolymers was studied by means of differential scanning calorimetry, mechanical analysis, and transmission electron microscopy. All of these techniques indicated a two‐phase structure. However, the degree of phase segregation was relatively low as measured by calorimetry, and in the same range as for conventional segmented linear polyurethanes. The existence of an important interphase can explain the appearance of plastic behaviour in hard domains at temperatures well below the polyamide melting points. The low ordering was confirmed by transmission electron microscopy. Only the ether‐amide copolymer with a composition in the phase inversion range exhibited a spherulitic, well‐defined polyamide structure.
Kinetics of polyamidation in solution, 2. reaction of diphenyl terephthalate and trimethylhexamethylenediamine in dimethyl sulfoxide
Authors: WeißKopf Klaus , Meyerhoff Günther
Published: April 2003

The kinetics of polyamidation was investigated for the reaction of diphenyl terephthalate as activated diester with trimethylhexamethylenediamine (1 : 1 mixture of 2,2,4‐ and 2,4,4‐trimethyl isomers) in dimethyl sulfoxide. The good solubility of the resulting polyamide (Trogamid®(poly(iminoterephthaloylimino‐x,y,z‐trimethylhexamethylene))) assured a reaction in which all reactants, especially the polyamide, were soluble. The conversion was followed by analysis of the phenol set free and by measuring the number‐average degree of polymerization P̄n of the polyamide. The reaction obeyed an overall second order with the principle of equal reactivity of functional groups fulfilled for P̄n ≿ 16. Deviations of this order of reaction were observed at the beginning of the reaction due to the enhanced reactivity of monomers and oligomers. The Arrhenius activation parameters were determined for the temperature range between 70 and 110°C.
Graph theory of configurational and viscoelastic properties of polymers, 2. Linear polymer chains containing small copolymer blocks
Authors: Yang Yuliang , Yu Tongyin
Published: April 2003

The graph theory of configurational and viscoelastic properties of polymers is extended to treat block copolymer chains. The analytical expressions for zero‐shear‐rate viscosity, η0, and steady‐state recoverable compliance, Je0, two important linear viscoelastic properties of polymers, are obtained for BmA2Bm, ABmA and BlABm type block copolymer chains. When the structure of a linear polymer is altered locally by incorporating a small amount of another monomer, the variation of the viscoelasticity cannot be ignored, their variation being strongly dependent on the block structure. Thus, the results obtained may prove useful for understanding and interpreting rheological data of block copolymers.
Funktionalisierung des perlcopolymerisationsprodukts aus methylacrylat und 1,4‐bis(vinyloxy)butan
Authors: Schott Herbert , Bretzger Waltraud
Published: April 2003

The ester groups of copolymer beads, prepared from methyl acrylate and 1,4‐bis(vinyloxy)‐butane, were substituted by aminolysis with hexamethylenediamine or aminoalcohols. The resulting gel carrying amino groups was transferred into an anion exchanger by alkylation with 2‐chloroethanol or into a cation exchanger by reaction with succinic anhydride. Hydrazinolysis of the starting copolymer beads resulted in gels with hydrazide groups which subsequently can be derivatized. Gels with hydroxyl groups linked to the matrix by means of spacers were obtained by reaction of the succinylated gels with 2‐aminoethanol. Phosphorylation of these hydroxyl groups afforded strongly acidic cation exchangers. The yields of the derivatized products are higher and the preparations are easier than those of the known methods. The 11 gel derivatives synthesized from the starting gel are mechanically stable, resistent to hydrolysis in the pH range between 1 and 14, chemically stable at temperatures up to 130°C and obtainable with a variety of pore sizes. The derivatized, cross‐linked polymer beads, applicable in aqueous systems as well as in organic solvents, should find application in chromatography, in solid‐phase synthesis and as basic gels in biotechnical processes.
Polymethacrylate‐supported linear polyethers as solid‐liquid phase transfer catalysts
Authors: Wakui Tadahiro , Xu Wen Ying , Chen Chi‐Sung , Smid Johannes
Published: April 2003

Oligo(oxyethylene)s immobilized as pendant groups on a polymethacrylate‐based resin were used as phase transfer catalysts in the reaction of solid alkali phenoxides with octyl halides in toluene and in the synthesis of benzyl acetate from benzyl bromide and solid alkali acetates in chloroform. The resins are cross‐linked homopolymers or copolymers of methyl ethers of oligo(ethylene glycol) methacrylates of the general formula H2CC(CH3)COO(CH2CH2O)n CH3 with n = 4 (MG4), 8 (MG8) or 22 (MG22), the comonomers being styrene, methyl methacrylate (MMA), acrylonitrile or 4‐vinylpyridine. The conversion of the organic halides into the respective products were found to be all pseudo first order reactions and the observed rate constants are proportional to the amount of added catalyst and decrease with increasing crosslinking density of the catalyst. Catalysts with longer oligo(oxyethylene) chains have considerably higher activity. Incorporation of more than 50 mol‐% MMA comonomer decreases the catalytic activity at least for the benzyl bromide reaction, but the structure of the comonomer has no significant effect. The catalysts are easily synthesized in large quantities from commercially available monomers.
Cationic polymerization of tetrahydrofuran initiated by multifunctional initiators
Authors: Cai Gang‐feng , Yan De‐yue
Published: April 2003

A series of multifunctional cationic initiators was synthesized from 1,5,9‐cyclododecatriene and from methylbenzenes by the Wohl‐Ziegler reaction with N‐bromosuccinimid. The initiators were treated with silver perchlorate to prepare star‐shaped polytetrahydrofurans with three to six arms.
Kinetic studies on the dehydrochlorination of poly(vinyl chloride) in the presence of a phase transfer catalyst
Authors: Howang Kyu Tak , Iwamoto Kazutoshi , Senō Manabu , Kise Hideo
Published: April 2003

The reaction rate of the dehydrochlorination of poly(vinyl chloride) in the presence of a phase transfer catalyst was studied. It was found that the order of reaction for NaOH and for the catalyst is 1,1 and 0,43, respectively. A mechanism like a radical‐chain transfer reaction of the zipper‐type may well account for the experimental data.
Excluded volume effect on polymer chains: Internal parts vs. free chain expansion
Authors: Ganazzoli Fabio
Published: April 2003

A self‐consistent Fourier configurational approach is used to describe the swelling of a polymer chain and of its inner parts in a good solvent. Minimization of the free energy yields the full spectrum of the expansion coefficients for the interatomic mean‐square distances assumed to have a Gaussian distribution with the actually perturbed second moment. Due to the repulsive effect of the outer segments, the internal parts are more expanded than a free chain with the same molecular weight under identical conditions, in good agreement with recent experimental findings, but contrary to what is predicted by mean‐field theories and by the blob model.
Functional metal‐porphyrazine derivatives and their polymers, 15. Synthesis and properties of poly(γ‐benzyl‐l‐glutamate)s containing covalently bound metalphthalocyanine moieties in the side chains
Authors: Hanabusa Kenji , Kobayashi Chihiro , Koyama Toshiki , Masuda Etsuko , Shirai Hirofusa , Kondo Yoshiyuki , Takemoto Kiichi , Iizuka Eisaku , Hojo Nobumasa
Published: April 2003

Metal‐2,9,16,23‐tetracarboxyphthalocyanines (1a — d) (Mt = Fe(III), Co(II), Ni(II) and Cu(II)) were transformed into their acid chlorides 2a — d which, by Friedel‐Crafts reaction with the benzyl groups of poly(γ‐benzyl‐L‐glutamate) (3), gave the polymers 4a — d. The resulting substituted poly(γ‐benzyl‐L‐glutamate)s were found to contain about 0,2 to 2,8 mol‐% of phthalocyanine rings covalently bound to the polymer main chain. Polymers 4a — d are soluble in chloroform, 1,4‐dioxane, dichloroacetic acid, DMF etc. The coordination spheres around the metalphthalocyanine rings were characterized by electronic and ESR spectra. The polymers could be shown to have α‐helical conformation, green or blue colored lyotropic mesophases being formed in concentrated solutions.
Conformation and gas permeability of poly(α‐amino acid) membranes
Authors: Kawai Tohru , Narita Hiroki , Lai Juin‐yih , Ebert Gotthold
Published: April 2003

The permeability of some poly(ϵ‐amino acid) (PAA) membranes like such of poly(N,δ‐carbobenzoxy‐L‐lysine) (PCBL), poly(N,δ‐carbobenzoxy‐L‐ornithine) (PCBO) as well as of copolymers of L‐lysine and carbobenzoxy‐L‐lysine to oxygen and carbon dioxide were determined at different water content especially with regard to their use for artificial lungs. The conformations of these polymer membranes were studied by means of IR‐spectra and X‐ray diffraction. The results on the diffusion coefficient obtained for PCBL and PCBO were analysed in terms of Eyring's theory. They suggest that the microvoids in the interstices between the α‐helices, assumed on the basis of X‐ray analyses, play an important role, especially below the glass transition temperature Tg of the side‐chains. This seems also to contribute partly to the diffusion of gas through the membrane even above Tg and results in an abnormally high “apparent activation energy” of diffusion in the wet state below Tg. It was found that the permeability of the membrane of partially decarbobenzoxylated PCBL for oxygen in a certain temperature range is higher than that for carbon dioxide. This has never been observed for any other synthetic polymer, because usually carbon dioxide has a higher solubility in these materials than oxygen. In the case of the partially decarbobenzoxylated PCBL membranes, however, the diffusion coefficient of carbon dioxide, and therefore the permeation of this gas, decreases much more than that of oxygen with increasing decarbobenzoxylation accompanied by the formation of β‐structure and concomitantly the formation of intermolecular hydrogen bonds. Obviously, this phenomenon may be responsible for the permselectivity of these membranes for oxygen compared with carbon dioxide.
ESCA study of new antithrombogenic materials: Surface composition of poly(propylene oxide)‐segmented nylon 610 and its blood compatibility
Authors: Yui Nobuhiko , Kataoka Kazunori , Sakurai Yasuhisa , Sanui Kohei , Ogata Naoya , Takahara Atsushi , Kajiyama Tisato
Published: April 2003

Surface composition and blood compatibility of a series of segmented polymers based on poly(propylene oxide) (PPO) and nylon 610 were investigated. Electron spectroscopy for chemical analysis (ESCA) measurements revealed that the chemical composition of PPO‐segmented nylon 610 surface is regulated by nylon 610 crystallization, and the PPO enrichment effect on the air‐facing surface was correlated with both the degree of crystallinity of nylon 610 and the nylon 610 crystallite thickness. Platelet adhesion was minimized for the copolymer having a long period of approximately 12 nm and a crystallite thickness of 6,5 nm. This copolymer surface had the same chemical composition as the bulk, indicating that the particular surface microstructure composed of crystalline and amorphous phases could be a determining factor for suppressing platelet adhesion.
Unified study of the mechanical and optical properties of polyoxymethylene applying the composite model for the temperature range from −60 to 120°C
Authors: Biswas Prabir K. , Sengupta Shyamal , Basu Asok N.
Published: April 2003

A unified study of the optical and mechanical properties of polyoxymethylene (POM) is attempted in the framework of the composite model for a wide range of temperature (−60 to 120°C) which covers a region well below and above the γ‐relaxation temperature. It was found that the existing two phase models for semicrystalline polymers are not adequate for interpreting the mechanical properties of POM over a wide temperature and drawing ratio range. The composite model takes into consideration the effects due to the change in crystallinity and orientation on drawing. The elastic moduli of the composite units are also calculated in terms of those of its constituents. The orientational changes on drawing were directly computed from the birefringence data. It was observed that the general agreement of the calculated and experimental values of the elastic moduli over the entire temperature and drawing ratio range is quite satisfactory.
Reusable heterogeneous catalysts of α‐amino acid racemization, 1. Immobilization of 4‐hydroxy‐3‐formylbenzenesulfonic acid (5‐sulfosalicylaldehyde) on strongly basic anion exchangers
Authors: Belokon' Yuri N. , Tararov Vitali I. , Savel'eva Tatiana F. , Saporovskaya Marina B. , Belikov Vasili M.
Published: April 2003

Strongly basic anion‐exchange resins in OH− form, partially neutralized with 4‐hydroxy‐3‐formylbenzenesulfonic acid (5‐sulfosalicylaldehyde) (SSA) could be shown to catalyse the racemization of neutral and basic optically active α‐amino acids in the presence of copper (II) ions at moderate temperatures (25‐45 °C). Under these conditions (S)‐asparagine is racemized without hydrolysis of its amide groups. The heterogeneous racemization of (S)‐alanine is accelerated by a factor of 880 as compared to a homogeneous reaction. The efficiency of heterogeneous catalysis depends on (1) the extent of neutralization of anion exchanger with SSA, (2) the type of the resin used and (3) the quantity of Cu(II) ions in the reaction mixture. The experimental data are in accordance with the fact that heterogeneous racemization of amino acids proceeds via the formation of a reactive copper(II)‐Schiff's base complex. The heterogeneous catalysts can be recycled. The anion exchangers can be regenerated and, if necessary, re‐used.
Polymerizable tautomers, 1. Tautomerism and polymerization of ethyl 3‐oxo‐4‐pentenoate
Authors: Masuda Seizo , Tanaka Masami , Ota Tadatoshi
Published: April 2003

Solvent effects on the tautomerism and polymerization of ethyl 3‐oxo‐pentenoate (1) were studied. Regression analysis of the tautomeric constant reveals that the equilibria depend on the polarity and hydrogen‐bond donor acidity of the solvents. The polymerization was investigated in benzene and acetonitrile. In both solvents, the kinetic results do not meet the conventional model of radical polymerization.
Phase transitions and defect structure in the lamellar surface of polyethylene and n‐alkane crystallites. Magic angle spinning 13C NMR studies
Authors: Möller Martin , Cantow Hans‐Joachim , Drotloff Hansotto , Emeis Detlef , Lee Kwang‐Sup , Wegner Gerhard
Published: April 2003

Variable temperature magic angle spinning 13C NMR experiments on linear alkanes and low molecular weight polyethylene allowed the observation of up to six carbon atoms at the chain ends near the surface of the lamellar crystallites. Conformational order‐disorder and intermolecular packing effects are reflected by the spectra. The effects are discussed with regard to the peculiar phase behaviour of the n‐alkanes and the fringed micella model for low molecular weight polyethylene. The solid‐solid transitions of nonadecane and hexatriacontane appear to be correlated with the occurrence of specific non‐liquid‐like conformational disordering. Thus, conformational defects were observed for the “rotator phase” which depend on the chain length and which vary along the chain. Whilst the center part of the chain remains all‐trans ordered, significant gauche defects were observed for the bonds at the chain ends. For a polydisperse low molecular weight linear polyethylene as well as for monodisperse octahexacontahectane reversible liquid‐like conformational disordering of the terminal chain segments could be detected when the melting point was approached. Hence, in this case the NMR spectra indicate pre‐melting of the lamella surface, while in case of the shorter n‐alkanes the occurrence of end‐gauche defects is correlated with solid‐solid transitions.
Lattice expansion by water absorption and side‐chain interactions in synthetic polypeptides having a urethane group in the side chains
Authors: Sasaki Shintaro , Iwanami Yoshimu
Published: April 2003

Two polypeptides with a urethane group in the side chains, poly(δ‐N‐methoxycarbonyl‐L‐ornithine) (PMCO) and poly(ε‐N‐methoxycarbonyl‐L‐lysine) (PMCL), were synthesized. Their crystal structures were investigated from X‐ray diffraction. In both polymers, the molecules take the α‐helical conformation, and helices are packed in a (pseudo)hexagonal array. The lateral size of the unit cell changes reversibly with relative humidity (rh), while the axial dimension is constant irrespective of water absorption. The expansion of unit‐cell volume for rh = 100% with reference to rh = 0% was 5,8% for PMCO and 7,1% for PMCL at 20°C. In the dry state, side chains are partly associated via hydrogen bonds. The dielectric behavior of these films is discussed in terms of side‐chain interactions.
Odd‐even variations in the melting points of some ethylene polyesters
Authors: Bhaumik D. , Mark J. E.
Published: April 2003

Molecular mechanics calculations on poly(ethylene adipate), poly(ethylene pimelate), and poly(ethylene suberate) indicate that the odd‐even variation in the melting points of the polyesters

n with the number y of methylene groups is due to differences in packing of the chains in the crystalline state.
New catalytic systems for acetylene polymerization
Authors: Catellani Marinella , Destri Silvia , Bolognesi Alberto , Albizzati Enrico
Published: April 2003

The synthesis of polyacetylene (PA) films, having interesting mechanical properties and improved air stability, was performed by means of catalytic systems with Ti(OBu)4 and aluminoxanes as cocatalysts (i.e. R2AlOAlR2, R2AlSAlR2, R2AlN(n‐Bu)AlR2). Scanning electron microscopic characterizations, density and specific surface area measurements are indicative of films more dense than the ones polymerized by means of the classic Shirakawa and Luttinger methods. Draw ratios up to 3,5 were observed.
Hydrophilic silicone rubber materials containing dimethylsiloxane and urethane moieties in the main chain
Authors: Koßmehl Gerhard , Neumann Walter , Schäfer Horst
Published: April 2003

By addition of various diisocyanates (5a, b) to oligomeric organosiloxanes, oily viscous polymers with urethane and siloxane moieties were obtained, which were crosslinked by reaction with 1–10 weight‐% of a peroxide. The resulting silicon rubber material is stable to hydrolysis. Films (F1 – F21) of these materials were characterized by their FMIR‐IR‐spectra. Some films (F3, F8, F10 – F12 and F17) show oxygen permeation values and contact angles which qualify these materials for contact lenses. The other films may be useful as materials for contact lenses after hydrophilizing.
Polymeric and oligomeric dimethylsiloxanes with alcoholic groups and their conversions into polymers with dimethylsiloxane and urethane moieties
Authors: Koßmehl Gerhard , Neumann Walter , Schäfer Horst
Published: April 2003

Addition of allyloxytrimethylsilane (2a) or allyl 2,3‐epoxypropyl ether (2c) to dihydrosiloxanes (1a and 1b) leads to the protected organoalkylsiloxanes 3a, 4a, 5a, 3c and 4c, which can be hydrolyzed to the corresponding hydroxyl compounds 3b, 4b, 5b and 4d. Addition of isocyanates 6a—c to these hydroxyl compounds results the model compounds 7a—c and 8a—c. Polymers 10a, b and 11a, b were prepared under similar conditions by addition of diisocyanates 9a, b to the hydroxyl compounds.
Syntheses of telechelic oligo‐ and poly(carboxypiperazine)s
Authors: Schwalm Reinhold , Heitz Walter
Published: April 2003

Poly(carboxypiperazine) is only accessible via low temperature polycondensation methods. The melting point of the polymer is higher than the temperature of its decomposition. Oligomers with piperidine end groups were prepared to determine the melting points of the pure polymer by extrapolation from the melting points of the oligomers. The decomposition temperatures were determined by thermogravimetry. These studies led to the design of meltable telechelics.
Functional polymers and sequential copolymers by phase transfer catalysis, 21. Thermotropic aromatic poly(ether sulfone)s: A new class of thermotropic aromatic main‐chain liquid crystalline polymers
Authors: Shaffer Timothy D. , Percec Virgil
Published: April 2003

Thermotropic aromatic poly(ether sulfone)s (3a — e) were prepared by phase transfer catalyzed (PTC) polyetherification of bis(4‐chloro‐3‐nitrophenyl) sulfone (1) with mesogenic aromatic diols. The synthesized polymers were characterized by differential scanning calorimetry and optical polarization microscopy to determine their phase behavior. All polymers appear to be amorphous. Only the polyethers based on 2,6‐dihydroxyanthraquinone (2a) and 1 exhibit enantiotropic liquid crystalline behavior. This demonstrates that fully aromatic polyethers can be prepared as thermotropic liquid crystalline polymers.
Equilibria in the anionic polymerization of methyl methacrylate, 1. Chain‐length dependence of the rate and equilibrium constants
Authors: Müller Axel H. E. , Lochmann Lubomír , Trekoval Jiři
Published: April 2003

The rate constants of polymerization and cyclization and the equilibrium constants of polymerization are calculated from kinetic data of the anionic oligomerization of methyl methacrylate initiated by methyl α‐lithioisobutyrate in THF at 25°C, and of the “disproportionation” of living oligomers. The numeric method reported earlier was improved. The rate constants of cyclization decrease with chain‐length, due to increasing steric hindrance. The rate constants of polymerization depend on the concentration of active centres, due to the formation of associates. Rate and equilibrium constants of polymerization decrease with chain‐length. This is discussed in terms of intramolecular coordination of the counterion with ester groups of the chain.
Compatibility of polymers in polymer blends investigated by gas chromatography
Authors: Klotz Stephan , Schuster Robert H. , Cantow Hans‐Joachim
Published: April 2003

Polymer‐polymer and polymer‐solvent Flory‐Huggins interaction parameters are given for the systems polystyrene/poly(methyl vinyl ether), polystyrene/solvent, and poly(methyl vinyl ether)/solvent. In principle polymer‐polymer interaction should be independent of the solvent probes used. In this study it was found that polymer‐polymer interaction is influenced by the solvent probe. These influences are discussed as a function of the chemical nature of the interacting vapour phase. However, these effects are not decisive for the phase behaviour of polymer blends. Phase separation was observed at high temperature. Gas chromatography measurements facilitated a quantitative thermodynamic description of the system polystyrene/poly(methyl vinyl ether) over a wide range of temperature and composition.
Die gitterstatistik des gaußschen parakristalls
Authors: Blöchl Georg , Bonart Richard
Published: April 2003

Hosemann's ideal paracrystal is characterized by the Gaussian error propagation of shortrange lattice distortions along the edges of the lattice cells. In a Gaussian paracrystal, however, the short‐range distortions propagate radially throughout space. In contrast to Hosemann's model there is no need for the lattice cells to be parallelepipeds in Gaussian paracrystals. Based on distance and directional fluctuations, a lattice‐independent description of long‐range distortions is introduced by its so‐called characteristics. Thus, the lattice factor describing the interference effect is found by a two‐fold Fourier transform similar to the approach of Warren and Averbach. This will be explained in detail in a following paper.
Der gitterfaktor des gaußschen parakristalls
Authors: Blöchl Georg , Bonart Richard
Published: April 2003

By using so‐called “characteristics”, the long‐range distortion in Gaussian paracrystals may be described in a way which is independent of the lattice, provided distance and directional fluctuations between neighbouring lattice points are used. By a two‐fold Fourier transform — similar to the approach of Warren and Averbach — the lattice factor, describing the interference effect of the Gaussian paracrystal, is found from the convolution of an ideal reciprocal lattice with a lattice‐independent profile function. Threadlike “one‐dimensional” Gaussian and ideal paracrystals are identical with each other. Making use of the two‐fold Fourier transform, Hosemann's K‐factor splits into isolated discs (“Scheibchen”) showing Lorentzian profiles. The profile function of two‐and three‐dimensional Gaussian paracrystals shows a Lorentzian‐2/3 or a Lorentzian‐2 profile, respectively. The different profiles are experimentally distinguishable when using a position‐sensitive detector. Thus, based on experimental results, paracrystalline lattice distortions with Gaussian characteristics are detectable.
Chain packing in two aromatic heterocyclic polymers, one of which has a ladder structure
Authors: Nayak Kasmath , Mark James E.
Published: April 2003

A semiempirical method was used to calculate the interaction energies in the ladder polymer poly(3,6‐dioxo‐1H‐2,3,6,6a‐tetrahydro‐2,6a,11‐triazaindeno[1,2‐b]pyrene‐2,8,9‐triyl‐1‐ylidene‐1‐nitrilo) (BBL, 1) and the single‐strand polymer poly(5,8‐dioxo‐4b,5,8,8a‐tetrahydro‐4b,8a,13,16‐tetraazadiindeno[1,2‐a:1,2‐i]pyrene‐3,10‐diyl) (BBB, 2), in order to elucidate their chain packing. The van der Waals contribution to the total intermolecular interaction energies was found to be more significant than the Coulombic one. The prediction of short‐range interplanar spacings in the neighborhood of 3,3 Å along the z axis (chains above one another) and 8,8 Å along the y axis (chains alongside one another) is in good agreement with X‐ray diffraction results.
Phase structure and compatibility studies in poly(ethylene oxide)/poly(methyl methacrylate) blends
Authors: Martuscelli Ezio , Silvestre Clara , Addonizio M. Luisa , Amelino Luciano
Published: April 2003

Morphology, crystallinity, and melting behaviour of solution‐cast films of poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends were investigated as a function of composition, using optical and scanning electron microscopy, differential scanning calorimetry, and dilatometry. Up to a content of about 40 wt.‐% of PMMA the blend films are completely filled with PEO spherulites, no separated domains of PMMA being observed. This observation suggests, in agreement with small angle X‐ray scattering analysis, that for such compositions the PMMA molecules are incorporated in interlamellar regions of PEO spherulites. Blends with higher content of PMMA show islands of crystalline PEO within a matrix of PMMA; large amorphous regions coexist with not well developed PEO spherulites. Addition of PMMA strongly increases the nucleation density for PEO crystals. The solubility parameters δ of PEO and PMMA were calculated from specific volume values as a function of temperature. It was found that at temperatures higher than that of PEO melting the difference δ(PEO) ‐ δ(PMMA) is very low suggesting that the two polymers are compatible in the melt. Compatibility of PEO and PMMA was also predicted by using a theoretical approach which allows to calculate the free energy of mixing as a function of composition and temperature.
Anionic polymerization of 4‐methyl‐2‐oxetanone
Authors: Jedliński Zbigniew , Kurcok Piotr , Kowalczuk Marek , Kasperczyk Janusz
Published: April 2003

Potassium solutions, obtained by contacting the metal mirror with a THF solution of a crown ether were found to initiate the anionic polymerization of 4‐methyl‐2‐oxetanone (1) (β‐butyrolactone). The tacticity of the resulting polymer 2 was established by means of 13C NMR spectroscopy. The results indicate that living polymers of 1 were formed, and the polymerization proceeds without abstraction of hydrogen from the monomer and no termination and transfer reactions take place.
Kinetics of the free radical copolymerization of diethyl maleate with methyl methacrylate
Authors: Braun Dietrich , Cei Gustavo
Published: April 2003

The kinetics of the free radical copolymerization of diethyl maleate (M1) with methyl methacrylate (M2) was studied in bulk at 60°C with azoisobutyronitrile (AIBN) as initiator. The reactivity ratios of the system were determined by means of 1H NMR spectroscopy. The obtained values show that diethyl maleate is not only unable to homopolymerize (r12 = 0) but also display a very low tendency to incorporate in the polymer chain (r21 = 370) under the present conditions. Molecular weight measurements showed that a normal, although very slow growth reaction involving diethyl maleate takes place. Therefore, chain transfer could be neglected in the kinetic analysis. The dependence of the initiation rate constant on the monomer feed was analysed by means of the inhibition method. An equation for describing the observed dependence of polymerization rate on feed composition was derived taking into account the influence of solution viscosity on the termination rate constant (diffusion theory).
The effect of TiBr4 on ethylene polymerization catalyzed by tetrabenzyltitanium
Authors: Giesemann Jürgen , Ernst Eberhard , Ernst Angela , Ulbricht Joachim
Published: April 2003

The kinetics of the ethylene polymerization catalyzed by Ti(CH2C6H5)4/TiBr4 in toluene at 0°C was studied. The effects of the mole ratio of the catalyst components and of the quantity of catalyst on the polymerization were investigated. Using the number of active centres, the rate constant of the propagation reaction was evaluated. The number of active centres was determined by quenching the polymerization with 1‐butanol tritiated at the hydroxyl group. Compared with the kinetic data of the catalyst system Ti(CH2C6H5)4/AlBr3, the present results indicate that the nature of the cocatalyst mainly affects the conditions for the formation of active centres, but has no essential influence on their reactivity. These results support the concept of monometallic structure of the active centres in Ziegler‐Natta catalysts.
Epitaxial polymerization of acetylene
Authors: Yamashita Yuhiko , Nishimura Setsuro , Shimamura Kaoru , Monobe Kazuo
Published: April 2003

Epitaxial polymerization of acetylene was studied using systematic series of homologous isomorphic compounds as substrates for the purpose of establishing techniques for preparing well oriented polyacetylenes. From electron microscopy, it was confirmed that polyacetylenes grow on the substrate in the form of fibrils whose orientation is strongly dependent on the lattice matching between polyacetylene and substrate crystals: e.g. with naphthalene and anthracene as substrates the fibrils assume zigzag orientation in three specific directions on the crystal but with biphenyl and terphenyl the zigzag fibrils assume predominantly two specific directions. The mechanism of epitaxial growth during polymerization on the various substrates is discussed on the basis of the features of the epitaxial fibrils.
Photochimie des polyamides aliphatiques, 5. Oxydation du polydodécanamide (PA12) photocatalysée par TiO2 et ZnO
Authors: Roger Agnès , Sallet Daniel , Lacoste Jacques , Lemaire Jacques
Published: April 2003

The influence of two photoactive pigments (ZnO and TiO2 in the rutile form) on the dual photochemistry occurring in polydodecanamide was analyzed, on analytical and kinetics grounds. Variations in the concentration of amino, hydroperoxide and imido groups as function of the photoactive pigment content were studied. At wavelengths longer than 300 nm, zinc oxide exhibits an inner filter effect at low content; an antagonist photocatalytic influence is observed at high content (5–10%). The inner filter effect and the photocatalytic activity of titanium dioxide are observed simultaneously even at low content of titanium dioxide (1–10%). At 254 nm and 25°C, the filter effect of ZnO is prevalent on the formation of amino and acidic groups. Titanium dioxide acts as a filter and a photocatalyst: the formation of amino groups is inhibited, whereas the rate of formation of acidic groups is apparently not modified.
Preparation and thermolysis of N‐ammonioamidates as model precursors of new type of segmented poly(ether‐urethane)s
Authors: Masuyama Araki , Iwasaki Tadashi , Okahara Mitsuo
Published: April 2003

N‐Ammonioamidates 2 (aminimides) containing a hydroxyl group, oxyalkylene units, and an alkylene chain or a phenylene group in an acyl moiety were prepared in satisfactory yields from the corresponding esters 1. By thermolyses in diglyme, cyclic urethanes (type of crown ethers) 3 and oligo(ether‐urethane)s 4 were formed, depending on the structure of the N‐ammonioamidates. The latter are applicable to the syntheses of new model compounds of segmented poly‐(ether‐urethane)s.
Réaction époxide amine: Réactivité du sulfonyl‐4,4′ dianiline vis‐à‐vis du groupement époxy
Authors: Grenier‐Loustalot Marie‐Florence , Cazaux Frédéric , Grenier Philippe
Published: April 2003

Mechanism and kinetics of the polycondensation of 4,4′‐sulfonyldianiline (2) with 2,3‐epoxy‐1‐phenoxypropane (1) were analysed in the absence or presence of a catalyst [N,N‐(dimethyl)‐benzylamine or BF3 complex]. Chemical data obtained by 13C NMR and HPLC show that secondary reactions (homopolymerisation, reaction of hydroxyl groups with the epoxy groups) take a prominent part.
A facile synthesis of monodisperse carboxylated polystyrene and derivatives
Authors: Argyropoulos Dimitris S. , Bolker Henry I.
Published: April 2003

A method is presented for the synthesis of monodisperse carboxylated polystyrene (3) and derivatives by a Friedel‐Crafts acylation of monodisperse polystyrene with ethyl oxalyl chloride (1). Saponification of the resulting α‐keto ester yields the randomly carboxylated copolymer, whose structure was confirmed by NMR and infrared spectra. Viscosity measurements and gel permeation chromatography showed that no chain cleavage operated during the process of functionalization. The value of the technique lies in its simplicity of execution and the availability of starting materials.
Synthesis and characterization of polyamine graft copolymers with a poly(2‐hydroxyethyl methacrylate) backbone
Authors: Maruyama Atsushi , Senda Eiichi , Tsuruta Teiji , Kataoka Kazunori
Published: April 2003

Radical copolymerizations were carried out with 2‐hydroxyethyl methacrylate (HEMA) and a polyamine macromonomer (1). 1H NMR, IR, liquid chromatography and turbidity measurements showed the polymer obtained to be poly[(HEMA)‐graft‐polyamine]. The monomer reactivity ratio for the polyamine macromonomer was found to be similar to that of a low‐molecular‐weight analogous monomer. Microphase separated structure was observed on thin films of the copolymer by means of transmission electron microscopy. Using the column method, the biomedical behavior of the copolymer was estimated in terms of its interaction with rat lymphocytes. Strikingly, the copolymer surface was found to differentiate the lymphocyte subpopulations without any added adjuvant protein.
Block copolymers with controlled interphase width. Effects of interphase and composition on domain dimensions
Authors: Bühler Fritz , Gronski Wolfram
Published: April 2003

Ultrathin osmium tetroxid stained sections of solution cast block copolymer films were studied by electron microscopy. Two morphological systems were prepared from diblock copolymers containing 80 wt.‐% styrene and 20 wt.‐% isoprene: Systems with asymmetric lamellar morphology cast from cyclohexane, a preferential solvent for PI; and spherical morphology of rubber spheres in a continuous PS matrix, cast from tetrachloromethane, a non‐selective solvent. For the two morphologies the variation of domain dimensions was studied in dependence of molecular weight in the range from 70 000 to 600 000 g/mol. Two types of block copolymers were investigated: Unmodified block copolymers and block copolymers containing 10 wt.‐% of a random interblock between the pure polystyrene and polyisoprene blocks. For both kinds of morphologies the domain dimensions of the unmodified systems vary with Mn2/3 as predicted by Helfand's theory. In the modified block copolymers a much weaker increase with Mn is found for both morphological systems. The results can be understood in terms of equilibrium domain dimensions controlled by an interfacial tension depending on both composition and sequence structure of the block copolymers.
Transformation of oligodimethylsiloxanols in the presence of a strong base. Reactivity enhancement of the siloxane bond by the adjacent hydroxyl group
Authors: Chojnowski Julian , Kaźmierski Krzysztof , Rubinsztajn Stawomir , Stańczyk Wlodzimierz
Published: April 2003

The kinetics of the base catalysed disproportionation of polydimethylsiloxanes having silanol end groups was studied using the model systems 1,1,3,3,3‐pentamethyldisiloxane‐1‐ol (1) and 1,1,3,3,5,5,7,7,9,9,9‐undecamethylpentasiloxane‐1‐ol (5) in 2‐propanol in the presence of alkali metal 2‐propanolates and in THF containing 2 vol.‐% of water in the presence of NaOH. The results did not confirm our earlier mechanistic proposition. Silanone is not formed intermediately. The process proceeds according to the kinetic law for a bimolecular process and shows a high negative value of activation entropy. However, the reaction exhibits some features better explained by an elimination‐addition than by an SN2 mechanism. The hydroxyl group exerts a specific role making the cleavage of the adjacent siloxane bond much easier. The reaction is also accelerated by the assistance of the alkali metal counter ion and its rate seems to be little dependent on the basicity of the nucleophile. A mechanism combining elements of both the SN2 and the elimination‐addition pathways is proposed.
Thermal dehydrochlorination of poly(vinyl chloride), 2. Transiently and permanently acting structural defects
Authors: Lukáš Rudolf , Přádová Olga
Published: April 2003

Samples with an increased content of chloroallyl structures were prepared by chemical degradation of poly(vinyl chloride) (PVC) using potassium tert‐butoxide. The samples were thermally dehydrochlorinated in an inert atmosphere, and their dehydrochlorination curves were determined by the continuous potentiometric method. The results show that the chloroallyl structures affect the dehydrochlorination of PVC only transiently. The same conclusion is obtained by an analysis of experimental data of the dehydrochlorination of PVC samples enriched in structures with the chlorine atom bound to the branching site (structures with the chlorine atom at the tertiary carbon atom). A general conclusion is that all structural defects, which facilitate the elimination of hydrogen chloride along the polymer chain and exist in the polymer before its heat stress, play only a transient role in the thermal dehydrochlorination of PVC. These structural defects initiate the splitting‐off of hydrogen chloride during the induction period of dehydrochlorination and form conditions for a gradually increasing effect of the basic initiation mechanism, which in the course of dehydrochlorination gives rise to chloroallyl structures. The formation of chloroallyl structures is brought about by a reaction between regular structural PVC units and s‐cis‐enone, dienone, or polyenone structures. A possible mechanism of this reaction, consisting in an interchain syn‐elimination of hydrogen chloride, is suggested.
Kinetics and mechanism of formation and properties of polymers composed of paired macromolecules
Authors: Korshak Vasili V. , Suprun Anna P. , Slonimskii Grigorii L. , Askadskii Andrei A. , Birshtein Tatyana M. , Vointseva Irina I. , Mustafayeva Balakhanum B. , Nikolskii Oleg G.
Published: April 2003

The influence of formation conditions on structure and properties of reaction products from two different macromolecules (paired polymers) such as polystyrene and poly(1,1,2‐trichlorobutadiene) or polystyrene and poly(vinyl chloride) is investigated. Mechanical properties, molecular mobility, heat resistance, thermostability, and fire resistance are shown to be regulated over a wide range by changing the molecular weight of the initial polymers, their ratio in the reaction mixture, etc. The interaction of different macromolecules in solution to form paired polymers is analyzed theoretically and experimentally. An analysis of structure and properties of the resulting products by refractometry, viscometry, sedimentation velocity, statistical analysis, and others shows that paired polymers are systems of the “coil‐in‐coil” type held together by chemical bonds in the zones of mutual penetration.
13C and 1H NMR study of polymers obtained by polymerization of styrene oxide using diethylzinc/water system as initiator
Authors: Kasperczyk Janusz , Jedliński Zbigniew J.
Published: April 2003

Styrene oxide was polymerized by the initiator ZnEt2/H2O and the structure of the resulting polymers was determined by means of 1H and 13C NMR spectroscopy. Both the crystalline and the amorphous fraction have regular head‐to‐tail structure indicating that the oxirane ring opens exclusively at the β position. The stereochemistry of the growth of the crystalline, highly isotactic fraction follows first order Markov statistics, while that of the amorphous fraction follows Bernoulli statistics.
Empirical molecular weight distribution functions as determined from gel permeation chromatography data
Authors: Jakeš Jaromír , Saudek Vladimír
Published: April 2003

Two‐ and three‐parameter functions commonly used for the description of the molecular weight distribution of polymers were determined from gel permeation chromatography data for 80 water‐soluble samples of polymers derived from glutamic acid. Two methods were applied: the moment method in which two or three different molecular weight averages are used, and a least squares adjustment method using the whole chromatogram. Convergence difficulties observed in the past were overcome, and a fully automated computer procedure was developed. The moment method, although virtually the only one still in use, often gives inexact results: sometimes the type of two‐parameter distribution is wrongly assigned, or the description of experimental data cannot be improved by adding yet another parameter. On the other hand, in all cases under study the least squares method gave a function which describes the real distribution within the limits of experimental error. Although the majority of samples could be described by employing one of the common two‐parameter functions, the more general three‐parameter function, encompassing all two‐parameter ones as special cases, has the advantage of wider applicability. It is shown that the standard gel permeation chromatography data often cannot provide reliable values of higher molecular weight moment averages, including M̄z. Hence, it may be inferred that in the description of the experimental molecular weight distribution curves the least squares method should be preferred over the moment method.
Molecular characterization of soluble poly(1,4‐divinylbenzene) obtained by anionic polymerization of 1,4‐divinylbenzene with lithium alkylamide as initiator
Authors: Kajiwara Kanji , Suzuki Hidematsu , Inagaki Hiroshi , Maeda Mizuo , Tsuruta Teiji
Published: April 2003

A series of soluble poly(1,4‐divinylbenzene) (PDVB) samples was prepared by anionic polymerization of 1,4‐divinylbenzene (DVB) in tetrahydrofuran with a varying amount of diisopropylamine. The dilute solution properties of the PDVB samples were examined with conventional methods including viscosimetry, sedimentation equilibrium, and light scattering measurements. The results suggest a considerable amount of long branches in soluble PDVB though not all of the pendant vinyl groups are consumed to form branches. A tree‐like model was proposed for the present system. The data were analysed quantitatively according to this model which yielded a consistent pair of values of the z‐average mean‐square radius of gyration 〈S2〉 and the intrinsic viscosity [η].
Synthesis of a rhodium‐poly(4‐vinylpyridine) complex: Electrochemical behaviour of a modified platinum electrode
Authors: Cancela Juan J. , Fernández‐Otero Toribio
Published: April 2003

Complexes of Rh(I) with 4‐vinylpyridine and poly(4‐vinylpyridine) were isolated and studied by infrared and electronic spectra and elemental analysis. The electrochemical behaviour of a platinum electrode coated with metal‐polymer complex was studied by consecutive potential sweeps. The complex was oxidized at potentials higher than 600 mV (S.C.E.) in 0,5 M H2SO4 and reduced at lower potentials. Consecutive sweeps produce a reticulation of the complex and therefore lead to electrode stabilization. The influence of the anodic and cathodic limits of the potential sweeps and of the metal to polymer ratio was also studied. The cathodic photoresponse of this electrode and its conductivity in a Fe2+ /Fe3+ solution is also reported.
Theta‐behaviour of poly(p‐tert‐butylstyrene)‐block‐poly(dimethylsiloxane)‐block‐poly(p‐tert‐butylstyrene)
Authors: Küçükyavuz Zühal , Küçükyavuz Savaş
Published: April 2003

The theta‐behaviour of poly(p‐tert‐butylstyrene)‐block‐poly(dimethylsiloxane)‐block‐poly(p‐tert‐butylstyrene) ABA type triblock copolymers containing ca. 28% by weight tert‐butylstyrene was studied in the selective solvents 1‐nitropropane and 2‐butanone using the phase separation method. The theta‐temperatures in these solvents were found to be 157°C and 31°C, respectively. The intrinsic viscosities of the copolymers in 2‐butanone (MEK) were obtained at different temperatures. The Mark‐Houwink‐Sakurada exponent α in MEK at 31°C is greater than 0,5, suggesting that the theta‐behaviour of block copolymers is different from that of the homopolymers due to the presence of repulsive interactions between incompatible blocks.
Molecular weights and molecular dimensions of perfluoropolyether fluids
Authors: Cantow Manfred J. R. , Larrabee Richard B. , Barrall Edward M. , Butner Richard S. , Cotts Patricia , Levy Frank , Ting Thomas Y.
Published: April 2003

The weight‐average molecular weights of a series of fractions from two structurally different types of perfluoropolyether fluids were determined by low‐angle laser light scattering. The limiting viscosity numbers of both sets of fractions were measured in Freon TF® and related to molecular weights. By using established polymer solution theory, the coil dimensions of the molecules were calculated. Samples from both sets of fractions were subjected to analysis by gel permeation chromatography and the coil dimensions were derived by using the principle of universal calibration. Results from both methods agree well. Bulk viscosities and molecular weights were correlated.
Addition polymerization of 1,4‐diethynylbenzene with 1,4‐benzenedithiol and properties of the resulting copolymer
Authors: Kobayashi Eiichi , Ohashi Toyoshi , Furukawa Junji
Published: April 2003

A novel addition polymerization of 1,4‐diethynylbenzene (1) with 1,4‐benzenedithiol (2) was studied under UV‐irradiation in toluene solution at −20°C. The addition polymerization was found to proceed rapidly and a pale‐yellowish polymer precipitated with the progress of the reaction (M̄n = 7500). A soluble polymer was recovered from the toluene solution by evaporation. Its M̄n value was estimated to be 3000. When an excess amount of 2 was used (mole ratio 1:2 = 2:3), the yield of the insoluble polymer increased. TG of the polymer indicated its decomposition point to be ≈500°C in air. The electroconductivity of the insoluble and soluble polymers was found to be 10−2 S · cm−1 and 10−5 S · cm−1 when doped with I2 at room temperature, respectively, and the conductivity was reversibly increased with increasing temperature up to 90°C. At T > 90°C the iodine was released and the conductivity decreased.