bluuebunny/crossref_metadata_2025 huggingface dataset:
Cationic polymerization of isobutyl vinyl ether catalyzed by ion exchange resin (polystyrene sulfonic acid)
Authors: Aoki Shuzo , Otsu Takayuki , Imoto Minoru
Published: April 2003

The Catalytic activity of polystyrene sulfonic acid (commercial cation exchange resin) has been investigated for the cationic polymerization of vinyl monomers. Styrene, α‐methylstyrene, and isobutyl vinyl ether polymerized in the presence of this cation exchange resin giving polymers with rather low molecular weights. The kinetic behaviour of polymerization of isobutyl vinyl ether is similar to that observed in the sulfuric acid‐catalyzed polymerization of styrene, but a diffusion‐controlled mechanism is proposed for the propagation reaction. The resulting poly(isobutyl vinyl ether) has an isotactic structure.
Etude de la cristallisation des polymères I. Structure lamellaire de polyoxyéthylènes de faible masse moléculaire
Authors: Arlif J. P. , Spegt P. A. , Skoulios A. E.
Published: April 2003

Seven low molecular weight polyethyleneoxide samples have been studied by means of low‐angle X‐ray diffraction technique and dilatometry.

The thickness of the crystalline lamellae of the polymer has been found exactly to correspond to the known length of the full extended polymer chains, the gap between the lamellae being of the order of 7 Å.

The relationship between the experimental value of molar volume and the molecular weight has been established and the specific volume of crystalline polyethyleneoxide has been deduced.

Near the melting temperature of the polymer a fractionation effect has been found to occur and its dependance upon the crystallization temperature has been examined.
Über polymere methylierte vinyi‐hydrochinone
Authors: Manecke Von G. , Bourwieg G.
Published: April 2003

Die radikalische Homopolymerisation verschieden methylierter Vinylhydrochinon‐Verbindungen wurde untersucht. Durch Copolymerisation von 1‐Vinyl‐2,4‐dimethyl‐3,6‐diacetoxy‐benzol mit Styrol und Divinylbenzol und sulfonierung der Polymerisate wurden Redoxharze erhalten. Die Austauschkapazität, die Redoxkapazität, die Quellungs eigenchaften und die Reaktionsgeschwindigkeit sowie das Redoxpotential wurden gemessen und die Werte untereinander in Beziehung gesetzt.
Thermoelastieity of rubber vulcanizates. I
Authors: Yamamoto Kazuhiko , Kusamizu Sumio , Fujita Hiroshi
Published: April 2003

A new method for evaluating the temperature coefficient of the unperturbed dimensions 0 of a polymer chain from stress‐temperature data was proposed assuming that the parameter C1 in the MOONEY‐RIVLIN equation (f = (C1 + C2/α)(α−1/α2), where f is the tensile force and α the elongation ratio) has the same form as the factor in the f vs. α relation predicted by the current theory of GAUSSIAN networks. Precise stress‐temperature measurements were performed for two cis‐1,4‐polybutadiene vulcanizates and one natural rubber vulcanizate, and the results were analyzed by the new equation and also by the familiar FLORY equation. The latter equation led to dln0/dT (T is the absolute temperature) which decreased with increasing α, as had been observed for many crosslinked polymers by previous workers. The new equation, on the other hand, gave values which were actually independent of α. These are 0.4 10−3 (deg.−1) for natural rubber and ‐0.4.10−3 (deg.−1) for cis1,4 polybutadiene. This latter value is sharply contrasted with 0.4.10−3 (deg.−1) reported by CRESPI and FLISI who used the usual FLORY equation, but is consistent, at least in sign, with −1.3 · 10−3 (deg.−1) that has been deduced from recent viscosity data of ABE and FUJITA in a series of chemically similar theta solvents. However, one must wait until the molecular interpretation of the C1 term in the MOONEY‐RIVLIN equation becomes available, in order to know whether the temperature coefficient of 0 calculated by the proposed method is physically meaningful.
The synthesis and properties of β‐vinylnylon 66
Authors: Baron Arthur L. , Marshall Richard A.
Published: April 2003

The homo‐ and copolymers of β‐vinylnylon 66 have been synthesized from β‐vinyladipic acid and hexamethylenediamine (and adipic acid). The cross‐linking reaction and chemical and physical properties of these polyamides are discussed.
Activation of poly[N‐(2‐hydroxypropyl)methacrylamide] for the binding of bioactive molecules, 1. Activation with 4‐nitrophenyl chloroformate
Authors: Lääne Ants , Haga Mati , Aaviksaar Aavo , Chytrý Vladimír , Kopeček Jindřich
Published: April 2003

Proper reaction conditions were determined for the activation of water‐soluble, biocompatible poly[N‐(2‐hydroxypropyl)methacrylamide] (1) by esterification with 4‐nitrophenyl chloroformate (2). The rate constants of hydrolysis and aminolysis of the 4‐nitrophenyl ester groups in resulting polymer 3 were compared. It was shown that at pH 8 – 9 the rate of aminolysis in water solutions is high enough for binding bioactive molecules via NH2 groups. Cobra venom acetylcholinesterase was bound to the activated polymer 3 and thermostability and immunogenicity of this product were studied.
Selective step‐growth phenol‐aldehyde polymerization, 2. Synthesis of 4‐tert‐butylphenol novolac resins and related open chain oligomeric compounds
Authors: Casiraghi Giovanni , Cornia Mara , Ricci Giovanni , Balduzzi Gianluigi , Casnati Giuseppe , Andreetti Giovanni Dario
Published: April 2003

Constitutionally regular all‐ortho 4‐tert‐butylphenol‐formaldehyde novolac resins were prepared free from cyclic compounds, by reaction of bromomagnesium 4‐tert‐butylphenoxide in aprotic nonpolar media with paraformaldehyde. Short syntheses of dinuclear to decanuclear methylene‐linked chain oligomers were also achieved via bromomagnesium ion‐assisted reaction of suitable phenolic precursors with paraformaldehyde or 5‐tert‐butyl‐2‐hydroxybenzyl alcohol.
Synthèse par voie radicalaire de polymères à extrémités hydroxylées, 12. Etude de la copolymérisation du méthacrylate de méthyle avec divers acrylates et méthacrylates. Détermination des microstructures
Authors: Brosse Jean‐Claude , Gauthier Jean‐Marie , Lenain Jean‐claude
Published: April 2003

Methyl methacrylate was copolymerized with butyl or isobutyl acrylates, and butyl, isobutyl, or 2,3‐epoxypropyl methacrylates, by hydrogen peroxide, in the presence of ethanol under UV irradiation (at 254 nm) at room temperature. The analysis of the microstructures was based on resonance splitting of the methoxy protons of MMA, depending on their environment. This splitting was not obtained with isobutyl and 2,3‐epoxypropyl methacrylates. All the products were found to be predominantly syndiotactic.
Secondary structure of peptides, 11. How to synthesize helical poly(L‐phenylalanine)?
Authors: Kricheldorf Hans R. , Müller Detlef , Stulz Josef
Published: April 2003

Polymerizations of L‐phenylalanine‐N‐carobxyanhydride(L‐Phe‐NCA) were conducted under various reaction conditions and the secondary structure of the resulting solid poly(L‐phenylalanine)s was examined by means of 50,3 or 75,4 MHz 13C NMR CP/MAS spectra. When primary alkylamines were used as initiators only α‐helix contents ≤ 60% were obtained regardless of solvent and temperature. However, a part of the β‐sheet structures was thermodynamically unstable and could be converted into α‐helices by reprecipitation. An α‐helix content > 90% was achieved only when weakly nucleophilic reagents, such as aromatic amines or water, were used as initiators in methylene chloride. A kinetic explanation of these results is discussed. Aprotic bases gave low yields of poly(L‐phenylalanine) and substantial amounts of low molecular weight side products. An α‐helix content ≥ 95%, was achieved when L‐Phe‐NCA was polymerized in pyridine at 100°C. The usefulness of IR spectra for the characterization of the secondary structure of poly(L‐phenylalanine) is discussed.
Active centre determination in ziegler‐natta polymerization. An examination of the allene inhibition method
Authors: Burfield David R.
Published: April 2003

A study of the adsorption of allene on VCl3, TiCl3 Type 1.1, and TiCl3 Type H catalysts has been made. In the absence of cocatalyst, allene adsorption is observed and in the case of the TiCl3 Type 1.1 catalyst rapid oligomerization of allene occurs. Activation with Al(C2H5)3 leads to a slow consumption of allene with VCl3 and TiCl3 Type H, but shows no distinct change for the TiCl3 Type 1.1 catalyst. The amount of “adsorbed” allene is generally higher than the number of active sites and this is attributed to adsorption on sites which are inactive in polymerization and to consumption of allene through side‐reactions.
Properties of liquid crystalline polymers in solution, 1. Determination of the molecular weight of polymethacrylates with mesogenic sidegroups
Authors: Springer Jürgen , Weigelt Franz Werner
Published: April 2003

Derivatives of poly(methacrylic acid) with mesogenic sidegroups are aggregated in solution. Through structural changes which also take place in the solid state, the fraction of the aggregates increases with storage time. The formation of aggregates depends on temperature and occurs relatively slowly. In solution, the degree of aggregation strongly depends on the solvent. This aggregation leads to relatively high tacticity in products obtained by radical initiated polymerisations.
Functional monomers and polymers, 106. Enantioface differentiation by using chiral polymers derived from (—)‐2‐exo‐hydroxy‐3‐bornanone
Authors: Liu Jui Hsiang , Kondo Koichi , Takemoto Kiichi
Published: April 2003

Chiral polymers containing 2,3‐exo‐dihydroxy‐3‐endo‐p‐tolyl‐3‐bornyl groups prepared by reaction of lithiated polystyrenes with (–)‐2‐exo‐hydroxy‐3‐bornanone (3), were treated with lithium aluminium hydride to yield products which can be used as reducing reagents. Asymmetric reductions of carbonyl compounds with LiAIH4 were carried out in the presence of both the chiral polymeric and 3‐endo‐p‐tolyl‐2,3‐exo‐bornanediol (4) as low molecular model compounds and the resulting enantiomeric excess was compared. The chiral polymers derived from 3 were found to be effective catalysts for the asymmetric reduction. The enantiomeric excess tends to increase with decreasing degree of crosslinking of the chiral polystyrene resins, exhibiting a high enantioselectivity in the case of chiral linear polystyrenes.
Miscibility in blends of polycarbonate and an aromatic polyester
Authors: Mondragon Iñaki , Cortazar Mila , Guzmán Gonzalo M.
Published: April 2003

Blends of the polycarbonate of bisphenol‐A (PC) with polyacrylate (PA), an aromatic polyester formed from bisphenol A and terephthalic acid/isophthalic acid, were prepared by both melt and solution casting, and their transitional behaviour was examined by differential scanning calorimetry (DSC) and thermo‐optical analysis (TOA). Each blend composition was found to have a single glass transition temperature by DSC and by TOA. This result suggests that polycaronate and polyarylate form blends containing a single amorphous phase. Ester‐carbonate interchange reactions during melt‐mixing were experimentally found to be unimportant. Melting point depression was used to estimate the blend interaction parameter χ12.
Structural investigations on cellulose tricarbanilate: Conformation and liquid crystalline behaviour
Authors: Zugenmaier Peter , Vogt Ulrike
Published: April 2003

The phase behaviour of cellulose tricarbanilate (CTC) in ethyl methyl ketone (MEK) solutions was studied in the concentration range of 0,2 – 0,8 g/ml as a function of the temperature. By analyzing the textures in the polarizing microscope and by differential scanning calorimetry experiments several different phase transitions and mesophases were detected. At a concentration below 0,6 g/ml CTC in MEK, phase transitions were observed from the crystalline through a liquid crystalline (cholesteric) to the isotropic state. At concentrations higher than 0,6 g/ml, a different behaviour of the CTC solutions was detected and several transitions were found, but only the cholesteric‐isotropic transition could be identified. The concentration dependence of the cholesteric‐isotropic transitions was determined over the whole concentration range. The conformation of the CTC molecule was studied and a stiff, almost cylindrically shaped 3/2 helix with a repeat distance of 15,25 Å is proposed.
Cationic homopolymerization of 1,1′‐diisopropenylferrocene
Authors: Chishti Asif S. , Jablonski Chester R.
Published: April 2003

1,1′‐Diisopropenylferrocene (1a) was homopolymerized using trifluoroacetic acid or boron trifluoride etherate as initiators, with excellent yields (>90%) of polymer (8100 < M̄n < 14700). Spectroscopic evidence established an initial protonation of 1a to give a tertiary monocarbenium ion (3) which does not readily undergo intramolecular cyclization (into 4). Analysis of isolated homopolymers by 1H and 13C NMR spectroscopy revealed significant residual unsaturation, consistent with facile chain transfer. Adventitious oxidation occurred during workup to give a mixed valence (Fe(II)/Fe(III)) polymer which could be distinguished spectroscopically from the unoxidized polymer.
Postirradiation polymerization and ESR studies of γ‐irradiated N‐tert‐butylacrylamide
Authors: Kiliç Soner , Baysal Bahattin M.
Published: April 2003

Postirradiation polymerization of γ‐irradiated N‐tert‐butylacrylamide was studied at 80, 85, 90, and 100°C, and the activation energy was found to be 183 kJ · mol−1. By ESR spectroscopy, the half‐life for the second order decay of the irradiated monomer was found to be 13,8 h at 25°C with a decay rate constant of 4,5 · 106 g · mol−1 · h−1. The effect of oxygen and sulfur dioxide on γ‐irradiated N‐tert‐butylacrylamide was also studied. It was observed that oxygen reacts with N‐tert‐butylacrylamide free radicals resulting in a characteristic peroxyl radical spectrum. The signal decays rapidly and disappears in about 100 h. The decay was found to be of second order with a rate constant of 1,3 · 107 g · mol−1 · h−1 and a half‐life of 3,8 h at 25°C. In contrast to the situation with atmospheric oxygen, an appreciable fraction of the free radicals does not react rapidly with sulfur dioxide. The changes in the ESR spectra indicate that at least a large fraction of the original N‐tert‐butylacrylamide radicals, generated in the irradiated sample, react with sulfur dioxide rapidly to give sulfonyl radicals. Their decay is second order with a rate constant of 4,5 · 106 g · mol−1 · h−1 and a half‐life of 8,3 h.
Cationic polymerization of 1‐azabicyclo[4.2.0]octane, 2. Reactivities of ions and ion‐pairs
Authors: Matyjaszewski Krzysztof
Published: April 2003

The cationic ring‐opening polymerization of 1‐azabicyclo[4.2.0]octane (1) was studied with initiators providing small and large anions, namely F⊖, Br⊖, I⊖, picryl(Pic⊖), CF3SO3⊖. In nitrobenzene as solvent the macroions and macroion‐pairs, independently of the anion size, propagate with the same rate constant kp+ = kp± = 7,0 · 10−3 mol−1 · l · S−1 at 35°C ( Δ HP≠ = 55 ± 5kj· mol−1, Δ SP≠ = 105 ± 11 j · mol−1 · K−1). This result strongly indicates that it is not the large size of anoins which is exclusively responsible for the equality kP+ = kP±. The structure of the onium ions, their strong solvation, and the resulting weak interactions with anions are primarily responsible for the observed equalities. In methanol as solvent polymerization proceeds 30 times slowlier than in nitrobenzene and ion‐pairs are more reactive by 40% than ions, in agreement with Enikolopyan's findings.
Structure of active centers and mechanism of the anionic polymerization of lactones
Authors: Hofman Andrej , Słomkowski Stanistaw , Penczek Stanistaw
Published: April 2003

The anionic polymerization of β‐propiolactone (βPL) in DMF initiated with CH3COO−K+ or CH3O−K+ has been found to proceed via the carboxylate ion as growing species. This is valid for all polymerization steps in the former system, starting from the first monomer addition, whereas in the latter CH3O−K+ was found to produce in the initiation reaction both alcoholate and carboxylate anions in almost equal properties. The alcoholate reproduces approximately half of itself in each subsequent step; thus, after a few addition steps all of the active species have become carboxylate ones. The anionic polymerization of ε‐caprolactone (εCL), on the other hand, can only be induced by alcoholates and the growing species are alcoholate anions. Carboxylate anions, even with crowed cations, are inactive as initiators of εCL. These conclusions are based on NMR studies of the end‐groups originating from the initiator and on UV‐VIs studies of the reaction products of the active species with 2,4,6‐trinitroanisole. The difference between the polymerizations of βPL and εCL are explained in terms of ring strain and conformation.
Oligomères amphiphiles obtenus par voie radicalaire, 3. Simulation et contrôle de la synthèse d'oligomères de i'acide acrylique et de i'acrylamide à extrémité thio
Authors: Pichot Christian , Pellicer Raymond , Grossetete Pierre , Guillot Jean
Published: April 2003

The synthesis of amphiphilic oligomers through radical initiated polymerization of hydrophilic monomers in the presence of long hydrocarbon chain thiols as transfer agents was simulated using a model based on a kinetic scheme similar to that proposed by Ikada. Taking into account the solvent as a secondary transfer agent, the weight fractions of different oligomer molecules and the average degrees of polymerization versus conversion were determined as a function of the mole ratio [thiol]/[monomer] and the solvent transfer constant. A relatively good agreement was found between the theoretical and the experimental values for acrylic acid (AA) and acrylamide (Am) oligomerizations. Oligomers terminated by the solvent could complete with thiol‐terminated oligomers. It is interesting that by modifying the simulation model, it is possible to estimate the amount of thiol necessary to keep the composition of the reactant mixture constant during synthesis, thereby eliminating the drift in the oligomer composition at high conversion.
Viscosity behavior of the polyelectrolyte poly(vinyl alcohol) having some intrachain crosslinks
Authors: Ochiai Hiroshi , Kurita Yuji , Murakami Ichiro
Published: April 2003

The viscosity behavior of aqueous poly(vinyl alcohol) (PVA)‐borax‐NaCl systems was investigated. The intrinsic viscosity [η] of PVA in borax solution increases with increasing borax concentration. In solutions containing both borax and NaCl, on the other hand, [η] decreases with increasing concentration of NaCl, and at high NaCl concentration phase separation is observed. In the absence of borax, [η] is nearly independent of the NaCl concentration. These results are interpreted in terms of a limited chain expansion due to charges and intrachain crosslinks simultaneously introduced in the PVA chain when the chain is complexed with negatively charged tetrahedral borate ions. The crosslinking density was estimated from the intrinsic viscosity [η]∞ at infinite ionic strength using the Kuhn and Majer equation.
The crystal structure of α‐TiCl3 and the reticular disorder introduced by ball‐milling
Authors: Gerbasi Rosalba , Marigo Antonio , Martorana Antonino , Zannetti Roberto , Guidetti Gian Pietro , Cojazzi Gianna
Published: April 2003

By X‐ray powder diffraction methods the crystal structures of α‐TiCl3 and of the products obtained by dry ball‐milling activation of this form were studied. TiCl3 microcrystals show initially a structural disorder in the positions of titanium atoms and the successive mechanical activation introduces into the structure some stacking faults, mainly associated to ±60° rotations of the triple layers ClTiCl. The structural investigation has been carried out by an accurate fit of observed X‐ray patterns to those calculated in correspondence of structures containing well‐defined disordered sequences and of likewise well‐defined crystallite sizes. Like γ‐TiCl3 and MgCl2, α‐TiCl3 is very sensitive to mechanical activation, which improves the performances of these three compounds when they are employed as catalysts, or supports for catalysts, in Ziegler‐Natta polymerization processes.
Polymere ammoniumsalze aus N,N,N′,N′‐tetramethylalkylendiaminen und N,N′‐alkylenbis(chloracetamid)en
Authors: Schindlbauer Hellmuth , Gusbeth Helmut
Published: April 2003

Long chain polymeric ammonium salts 3a–g and 4a were prepared in DMF/H2O from N,N,N′,N′‐tetramethylalkylenediamines 2a and 2b and N,N′‐alkylenebis(chlorocetamide)s 1a–g. Some of them can be casted to clear transparent sheets. The chlorine atoms in 1a – g are activated by the adjacent carbonyl amino group. The polymer from N,N′‐tetramethylenebis(chloroacetamide) (1d) and N,N,N′,N′‐tetramethylhexamethylenediamine (2b) shows an intrinsic viscosity of 61 ml/g, the highest value known for polyelectrolytes so far. The intrinsic viscosity decreases with increasing numbers of CH2‐groups in the monomers. The polymeric ammonium salts 3a – g and 4a give sheets from DMF solutions, which are soluble in water and stable under normal conditions. Polymers which are best suitable for the preparation of sheets show less hygroscopicity than the others, due to their structure. Intrinsic viscosities were calculated from the reduced specific viscosities measured in 0,4 M KCl but may be also determined in water by the method of Yuan et al., plotting the reduced specific viscosities as a function of 1/√c.
Synthesis of an acryloyl‐type polymer pending D‐glucose analog of N‐acetylmuramyl‐L‐alanyl‐D‐isoglutamine
Authors: Ouchi Tatsuro , Sakamoto Yoshiomi , Jokei Satoshi , Chikashita Hidenori
Published: April 2003

Poly{1‐{3‐[O‐1‐(1‐carboxyethylaminocarbonyl)ethyl]‐6‐O‐D‐glucopyranosylcarbonyl}ethylene} (3b) was synthesized as the lipophilic and polymeric model of 1‐{N‐[2‐(2‐acetylamino‐2‐deoxy‐3‐O‐D‐glucopyranosyl)propionyl]‐L‐alanylamino}glutamic acid (1) to the minimum required structure for the eimmunoadjuvant activity of bacterial cell wall. N‐[2‐(6‐O‐acryloyl‐1,2‐O‐isopropylidene‐α‐D‐3‐O‐glucofuranosyl)propionyl]‐L‐alanine benzyl ester (6) was prepared as a key monomer in the synthesis. The homopolymerization of this monomer was carried out in benzene at 50°C using 2, 2′‐azoisobutyronitrile as radical initiator to give polymer 7. From the results of copolymerization with styrene, the values of Q and e for the acryloyl type monomer 6 were estimated to be 2,0 and 0,11, respectively. The removal of isopropylidene and benzyl protecting groups from homopolymer 7 was carried out by acidic treatment with trifluoroacetic acid/water (vol. ratio 6:1) and by catalytic hydrogenolysis with palladium carbon in acetone, respectively, to afford the homopolymer 3b.
Etude du prépolymère époxyde par chromatographie et 1H NMR à 350 mhz, 2
Authors: Gulino Danièle , Galy Jocelyne , Pascault Jean Pierre , Pham Quang Tho
Published: April 2003

The epoxy resins (TGMDA) obtained from 4,4′‐methylenedianilic (2) and 1‐chloro‐2,3‐epoxypropane (epichlorohydrin) were found to consist of oligomers with large distribution of molecular weights and functionalities. The structure of the main components separated by preparative gel permeation chromatography and by high pressure liquid chromatography (HPLC) was studied by 1H NMR. The best separation was obtained by HPLC on a preparected TGMDA with tert‐butyl isocyanate at 60°C. For the impurities, as found with DGEBA prepolymers, we identified primary and secondary alcohol groups on chain ends but also secondary amino groups inside the oligomer chains.
The influence of molecular interaction on polymerization, 8. Copolymerization of monomethyl itaconate with 2‐naphthyl methacrylate
Authors: Boudevska Hrissanta , Todorova Olga
Published: April 2003

The copolymerization of monomethyl itaconate (monomethyl 2‐methylenesuccinate, MMI) with 2‐naphthyl methacrylate (2‐NM) initiated with 2, 2′‐azoisobutyronitrile (AIBN) in solvents of different dielectric constants and capability to form hydrogen bonds was investigated. The reactivity ratios of the monomer pairs in the different solvents are as follows:

IR and 1H NMR spectroscopy studies show the influence of the solvent on the capability of the monomers to form hydrogen bonds and donor‐acceptor associates. The changes in the reactivity ratios of both monomers are attributed to the interaction observed between the monomer molecules as well as between the molecules of the monomers ad the respective solvent.
Préparation de polystyrène de masse éalevée à chaîcne aliphatique ou noyaux aromatiques deuteriés
Authors: Lapp Alain , Beinert Gérard , Picot Claude
Published: April 2003

Isotopically substituted styrene, (phenyl‐2H5) styrene (3), and selectively labled styrene, [alpha;, beta;‐2H2] styrene (6), were prepared by the classical two step synthesis, starting with the correspondingly labeled compounds. By anionic polymerization in an inert atmosphere labeled high molecular weight polystyrences 10 and 11 were prepared.
HPLC analysis of cyclo‐oligoamides 6 and 66
Authors: Guaita Cesare
Published: April 2003

A new HPLC method for cyclo‐oligoamides 6 and 66 separation is proposed. Using an RP 8 column and an H2O/CF3CH2OH mixtures, all cyclic amides up to the decamer were separated and quantitative results were obtained using an internal standard.
Examples of triphase reactions involving a crosslinked polymer, a solid, and a liquid phase
Authors: Hodge Philip , Khoshdel Ezzatollah , Waterhouse Janette
Published: April 2003

Several reactions involving crosslinked polymers, a solid, and a liquid phase were investigated. Witting reactions between crosslinked polymers (1 and 5) contaning phosphonium salt residues, solid potassium carbonate, and aldehydes in tetrahydrofuran were found to proceed satisfactorily, even in the absence of a phase transfer catalyst. The Oxidation of 2‐phenyl‐1,2‐propanediol in methylene chloride by solid sodium periodate (but not postassium periodate) is catalysed by the periodate form (9a) of an anion exchange resin. The reaction of 1‐bromooctane in benzene, tetrahydrofuran, or acetonitrile with potassium cyanide or sodium cyanide and of benzyl bromide in tetrahydrofuran or acetonitrile with potassium acetate or sodium acetate are catalysed only slightly, if at all, by the cyanide or acetate forms (9e and 9f) of an anion exchange resin. Crosslinked polymers containing crown ether residues catalyse the reaction of 1‐bromooctane in toluene with sodium iodide. It is not clear how the crosslinked polymers and solid reagents manage to react with each other, but possible mechanisms are discussed. The importance of carrying out control reactions in such studies is stressed.
Functionalized polyionenes, 3. Polyionenes with pendant l‐menthyloxymethyl groups and chiral recognition by means of hydrophobic domains
Authors: Suzuki Yasuzo , Tazuke Shigeo
Published: April 2003

To understand hydrophobic interaction as a function of polymer structure, the binding of 1‐anilino‐8‐napthalenesulfonic acid magnesium salt (ANS) by polyionenes was investigated by means of fluorescence spectroscopy. Three ionenes having ammonium groups in the main chain and pendant l‐menthyloxymethyl (PIPM‐6, OIM‐6)

PIPM‐6: poly[(dimethyliminio)hexamethylene(dimethyliminio)methylene‐5‐(l‐menthyloxy‐methyl)‐l,3‐phenylenemethylene dibromide]. OIM‐6: poly[(dimethyliminio)hexamethylene‐(dimethyliminio)‐5‐ethyl‐5‐(l‐menthyloxymethyl)‐2,8‐dioxo‐3,7‐dioxanonamethylene dichloride]. PIA‐6: poly[(dimethyliminio)hexamethylene(dimethyliMINIO)‐5‐(9‐anthryl‐methyl)‐2,8‐dioxo‐3,7‐dioxanonamethylene dichloride].

OR 9‐anthryl groups (PIA‐6) were used together with their model compounds. The emission intensity of aqueous solution of ANS in the presence of PIPM‐6 an OIM‐6 is about 40 and 90 times that in pure water, respectively, indicating that a hydrophobic domain is effeciently formed in water. The corresponding emission increment in the presence of PIA‐6 is only 8 times larger than that in pure water. These results suggest that the hydrophobic domains formed by OIM‐6 and PIPM‐6 are less polar than those formed by PIA‐6 and, consequently, the l‐menthyloxymethyl group is more hydrophobic than the anthryl group. The reduction of viscosity in salt solution runs parallel with the strength of hydrophobic interaction. The emission intensity of dansyl‐D‐phenylalanine is 1,3 times higher than that of dansyl‐L‐phenylalanine in the presence of PIPM‐6. These results indicate that the hydrophobic domains formed by PIPM‐6 have some ability of chiral recognition.
Synthesis and X‐ray photoelectron spectroscopy of poly(α‐ethyl‐α‐methyl‐β‐propiolactone) terminated with a perfluoroalkyl group
Authors: Albert Brigitte , Jérôme Robert , Teyssié Philippe , Pireaux Jean‐Jacques , Verbist Jacques Joseph
Published: April 2003

Perfluorinated carboxylates are efficient initiators of the α‐ethyl‐α‐methyl‐β‐propiolactone polymerization resulting in perfluoroalkyl‐terminated polyester. The X‐ray photoelectron spectra of the C8F17‐end‐capped polyester agree with an enrichment in fluorine atoms of the surface layer corresponding to an average number of 7 perfluoro groups per chain or to 36,6 wt.‐% of C8F17‐groups instead of 8,4 wt.‐% as calculated for a random distribution.
Polymeric schiff's base chelates and their precursors, 7. Dioxygen binding and catalytic oxidation of 2,6‐di‐tert‐butylphenol
Authors: Wöhrel Dieter , Bohlen Heike , Aeinger Christa , Pohl Dieter
Published: April 2003

Dioxygen binding and catalytic oxidation of 2,6‐di‐tert‐butylphenol(9) were investigated by employing various low molecular chelates (1 and 2), covalently or coordinatively bound polymeric chelates (3, 4, 5, 6, and 7), and polymeric Schiff's base chelates (8). Particularly the covalently bound polymeric chelates 3 and 4 were found to exhibit activities similar to low molecular 1 in regard to dioxygen binding. It is suggested that these polymers can reversibly form mononuclear superoxo‐complexes. In the oxidation of 9 the covalently bound polymeric chelates 3 – 5 exhibit good activity which does not decrease after repeated use.
Polymers from renewable sources, 1. Diamines and diisocyanates containing difurylalkane moieties
Authors: Cawse John L. , Stanford John L. , Still Richard H.
Published: April 2003

Furan‐based diisocyanates and diamines were prepared unambiguously as potential monomers for polyurethane and polyamide production, starting from methyl furoate and furfurylamine, respectively. The syntheses were optimized and the product identity was confirmed by elemental analysis, IR and NMR spectroscopy, and also by preparation of derivatives which were similarly characterized.
Untersuchungen zur klärung der sensibilisierten photodegradation von polystyrol in lösungen, 2. Energieübertragungsphänomene
Authors: Woliński Leszek , Wilkowski Konrad , Turzyński Zbigniew
Published: April 2003

A new approach is presented to explain “the sensitized photodegradation effect”, which was observed in polystyrene solutions irradiated with the light of a mercury lamp of wavelength λ ≥ 270 nm. The radiationless electronic excitation energy transfer from solvent molecules as energy donors to polystyrene (PS) macromolecules is considered to be the main factor influencing the polymer photodegradation rate in solution. Possible mechanisms of the energy transfer are discussed, the total energy transfer rate in eight investigated PS‐solvent systems is evaluated and compared with PS photodegradation rates, determined by light scattering in the first part of this series.
Temperature dependence of the viscosity of dilute poly(N‐vinylcarbazole) solutions in 1,4‐dioxane
Authors: Urizar Mercedes , Rodriguez Matilde , León Luis Manuel , Gonzalez M. Carmen , Zamora Fernando
Published: April 2003

The dependence of the viscosity of dilute solutions of poly(N‐vinylcarbazole) in 1,4‐dioxane on the temperature is studied by Moore's treatment. The numerical values of the constants from this treatment Ke, Kβ, and β indicate that this polymer in 1,4‐dioxane assumes the characteristic behaviour of flexible polymers. The numerical values of the parameters KΘ and B from the Stockmayer‐Fixman plot and the Mark‐Houwink constants K and a are determined and the temperature coefficient of the unperturbed dimensions is evaluated for this system.
Enantioselective hydrolysis of dipeptide amino acid esters by di‐ and tripeptide‐type L‐histidine derivatives in a bilayer vesicular system
Authors: Ohkubo Katsutoshi , Ogata Harumi , Yamaki Kazuhiro , Yamashita Kohichi
Published: April 2003

The enantioselective hydrolysis of dipeptide‐type amino acid esters (Z‐(L)‐Ala‐(L or D)‐Ala‐PNP (5a), Z‐(L)‐Ala‐(L or D)‐Leu‐PNP (5b), and Z‐(L)‐Ala‐(L or D)‐Phe‐PNP (5c)) by di‐ or tri‐peptide nucleophiles (Z‐(L)‐Leu‐(L)‐His (2a), Z‐(L)‐Phe‐(L)‐His (2b), and Z‐(L)‐Leu‐(L)‐His (3)) in the bilayer vesicular aggregates of didodecyldimethylammonium bromide (6) resulted in the enantiomer rate ratio of LL/LD = 1, 1 to 18, the value of which was considerably higher than that (L/D = 1,0 to 4,6) in the hydrolysis of Z‐(L or D)‐Ala‐PNP (4a), Z‐(L or D)‐Leu‐PNP (4b), and Z‐(L or D)‐Phe‐PNP (4c) by the identical vesicular system and that (L/D = 0,7 to 3,1) in the hydrolysis of the dipeptide substrates 5a – c by Z‐(L)‐His (1) and 6. The high enantioselectivity (LL/LD = 18) in the hydrolysis of 5c by the system of 2a and 6 was enhanced to be LL/LD = 36 by lowering the temperature from 25 to 10°C.
Thermodynamische verträglichkeit und wechselwirkungsparameter des systems oligoethylenglycol‐oligopropylenglycol
Authors: Shilov Valeri V. , Gomza Yuri P. , Kovernik Grigori P. , Lipatov Yuri S.
Published: April 2003

The thermodynamics of the binary system oligo(ethylene glycol) (OEG) ‐ oligo(propylene glycol) (OPG) is investigated by lightscattering. The Flory‐Huggins interaction parameter χ12 for this system is determined by the decrease of the OEG melting point in a mixture with OPG. At 310,8 K the system is compatible in the concentration range between 0 and 30 vol.‐% of OPG in the mixture. The analysis of the temperature dependence of χ12 according to the novel Flory theory leads to the assumption that mixing in this system occurs at a lower critical mixing temperature.
The molecular structures of methacrylates with bulky ester substituents, (RS)‐1,2,2,2‐tetraphenylethyl methacrylate and (1S, 2R)‐(+)‐1‐benzyl‐3‐dimethylamino‐2‐methyl‐1‐phenylpropyl methacrylate
Authors: Kageyama Hiroyuki , Yanagisawa Yoshihiko , Kasai Nobutami , Okamoto Yoshio , Yashima Eiji , Takeda Takahiro , Hatada Koichi
Published: April 2003

The molecular structures of (RS)‐1,2,2,2‐tetraphenylethyl methacrylate (TrBzMA) and (1S, 2R)‐(+)‐1‐benzyl‐3‐dimethylamino‐2‐methyl‐1‐phenylpropyl methacrylate (ChMA) were determined by means of X‐ray diffraction: (RS)‐TrBzMA .0,5C6H6; triclinic, space group P1, a = 9,271(2), b = 33,965(4), c = 9,167(2) Å, α = 90,26(2), β = 118,80(2), γ = 88,03(2)°, and Z = 4; ChMA; monoclinic, space group P21, a = 12,482(1), b = 9,184(1), c = 9,246(1) Å, β = 93,49(1)°, and Z = 2. Both structures were solved by the direct method and refined by the block‐diagonal least‐squares procedure to R = 0,054 and 0,057 for non‐zero reflections, respectively. Both of the two crystallographically independent molecules of TrBzMA have the same structure; each molecule has a synperiplanar (sp) conformation as to the CC and CO double bonds about the C(1)C(2) bond and also an sp conformation as to the CO and CO bonds about the C(1)O(1) bond. The ChMA molecule has an antiperiplanar (ap) and a sp conformation about the C(1)C(2) and C(1)O(1) bonds, respectively.
Expansion coefficients of hydrolysed polyacrylamides from intrinisc viscosities
Authors: Kulkarni Rajendra A. , Gundiah Subbaraya
Published: April 2003

Partially hydrolysed polyacrylamide samples were used as model polyelectrolytes and the variations of the intrinsic viscosities with the extent of hydrolysis and molecular weight were used to determine the relative applicability of the various macroion expansion theories. Expanison coefficients solely attributable to the presence of electrostatic charges were calculated with reference to the intrinisic viscosities of the parent polyacrylamides, assuming that the polyacrylamide corresponds to the discharged state of the macroion from hydrolysed polyacrylamides. Similarly, total expansions and expansions attributable to long‐range interactions were evaluated using the estimated intrinsic viscosities at the theta temperature of the parent polyacrylamide and the hydrolysed sample, respectively. The electrostatic expansion coefficients are independent of molecular weight and the long‐range expansion coefficients are almost independent of the extent of hydrolysis at high charge densities. In the absence of closed expressions predicting the variation of the expansion coefficients with the concentration of ionizable groups, equivalent expressions based on different theories were deduced assuming that i2/Cs is proportional to the concentration of ionizable groups where i is the extent of ionization of the polyelectrolyte and Cs is the concentration of the added salt. The variation of the electrostatic expansion coefficient with the charge density could not be represented according to any of the theories on macroion expansion. However, attributing the total expansion to the presence of electrostatic charges alone, the Fixman and Chien‐Ishihara theories allow a good representation of the data. At very low charge densities, the expansions due to long‐range interference effects also can be accounted for by the Fixman and Chien‐Ishihara theories.
Charakterisierung von disperisionen durch gekopplete H2O/D2O‐ultrazentrifugenmessungen
Authors: Mächtle Walter
Published: April 2003

The particle size distribution is one of the most important characteristics of aqueous polymer dispersions (diameter range 20 < D < 2000 nm). In addtion, the knowledge of the average particle density ρPM, the density distribution, and the particle refractive index nPM gives information about the chemical composition of dispersions. We report of an ultracentrifuge method which allows to determine all these values simultaneously in one single run. For that purpose the dispersion is measured simultaneously in 3 media of different density, i.e., in H2O, H2O/D2O (1:1, by wt.), and D2O. We use a preparative ultracentrifuge with an analystical rotor with trubidity optics, but instead of an 1‐cell‐rotor an 8‐cells‐rotor and a multiplexer are used. In order to measure very small and very large particles simultaneously in one single run we do not work at the usual constant number of rotor revolutions, but at a rate of revolutions increasing from 0 to 40000 min−1. The ultracentrifuge is connected with a computer on‐line. The calculations are based on Stokes' law and Mie's light scattering theory for homogeneous isotropic spherical particles.
Syntheses and properties of tertiary peptide bond containing‐polypeptides, 3. Syntheses of monodisperse‐sequential polypeptides having the sequence of L‐leucyl‐L‐leucyl‐L‐leucyl‐L‐prolyl‐L‐prolylglycine
Authors: Narita Mitsuaki , Nagasawa Satoshi , Chen Junn‐Yann , Sato Hisaya , Tanaka Yasuyuki
Published: April 2003

In order to demonstrate the usefulness of the “peptide segment separation method” for syntheses of large peptides and proteins, a model series of sequential polypeptides, Boc‐[(Leu)3‐(Pro)2‐Gly]n‐OBzl (n = 4, 6, 8, 10, and 12), were prepared by the reaction of Boc‐[(Leu)3‐(Pro)2‐Gly]2‐OH with H‐[(Leu)3‐(Pro)2‐Gly]n‐OBzl (n = 2, 4, 6, 8, and 10) using dicyclohexylcarbodimide and 1‐hydroxy‐1 H‐benzotriazole as coupling reagents. The resulting peptides are assembled by the sequence of Gly‐(Leu)3 separated by the (Pro)2 sequence. Regardless of the increase in peptide chain length of the amino component, the coupling reactions with 1‐methyl‐2‐pyriolidone were achieved in high yields. Throughout the investigation, excellent solubility in usual polar solvents used for peptide syntheses is preserved. The purification of the peptide series by recrystallization could be completely achieved and HPLC on a gel filtration (styrenedivinylbenzene copolymer) column showed all the peptides to be monodisperse.
Micellization of a radial copolymer with four polystyrene‐block‐polybutadiene branches
Authors: Procházka Karel , Glöckner Gottfried , Hoff Miloš , Tuzar Zdeněk
Published: April 2003

Similarly to the three‐block copolymer poly(styrene‐b‐butadiene‐b‐styrene), a radial block copolymer with four brances consisting of inner polybutadiene and outer polystyrene blocks forms, in a mixed solvent tetrahydrofuran/ethanol, spherical micelles with a polybutadiene core and polystyrene shell. The equilibrium between these micelles and the molecularly dissolved copolymer was studied as a function of the solvent composition by means of light scattering, sedimentation velocity, and GPC. The sedimentation diagrams were interpreted taking into account the Gilbert theory of mobile equilibrium in systems of associating macromolecules.
Novel syntheses of alternating copolymers with amide and thioether linkages by polyaddition reactions of bifunctional cyclic iminoethers with dithiols
Authors: Nishikubo Tadatomi , Iizawa Takashi , Tokairin Atsushi
Published: April 2003

Alternating copolymers with amide and thioether linkages were synthesized by addition reactions of bisoxazolines 1a – 1f and bisoxazines 2a and 2b with dithiols 3a – c in aprotic polar solvents. The reactions of the aromatic bifunctional cyclic iminoethers such as 1a, 1c, 2a, and 2b with the dithiols 3a and 3c in N‐methyl‐2‐pyrrolidone gave polymers with high molecular weight. However, the reactions of the aliphatic derivatives such as 1e and 1f with dithiols as well as the reactions of the bifunctional cyclic iminoethers with 3b led to polymers of low molecular weights. The reactions of methyl substituted bisoxazolines 1b and 1d with dithiols gave also polymers of low molecular weight.
Electro‐optical effects of azo dye containing liquid crystalline copolymers
Authors: Ringsdorf Helmut , Schmidt Hans‐Werner
Published: April 2003

The synthesis and phase behaviour of azo dye containing liquid crystalline side group copolymers are described. These Copolymers show the same electro‐optical effects as low molar mass guest‐host systems. Their macroscopic oriented nematic structure can be frozen in below the glass transition temperature resulting in a polymer film with dichroic properties. The behaviour of the copolymers (phase behaviour, surface and electric field orientation) can be improved via mixtures with low molar mass liquid crystals.
Segmented block copolymers of uniform chain length and defined structure, 2. Investigation of some physical properties
Authors: Krüger J. K. , Marx A. , Roberts R. , Unruh H.‐G. , Bitar M. B. , Nguyen‐Trong Hao , Seliger H.
Published: April 2003

Some physical investigations of segmented block copolymers of uniform chain length and defined structure and their constituents are described. Special attention was payed to the thermal behaviour of these new substances with respect 1. to the phase transformations in the solid and liquid state and 2. to the thermal stability of the materials. Several of these oligomers show phase transitions in the solid state. In some instances, the morphology of the solid material depends strongly on the sample history. The influence of the crystallization conditions is discussed. For the special case of esters of 4,4′‐isopropylidenediphenol (bisphenol A) with isophthalic acid detailed investigations by dielectric and Brillouin spectroscopy of the glass‐forming process are presented.
Propene polymerization with a magnesium chloride‐supported Ziegler catalyst, 2. Molecular weight distribution
Authors: Keii Tominaga , Doi Yoshiharu , Suzuki Eiichi , Tamura Masanori , Murata Masahide , Soga Kazuo
Published: April 2003

The kinetic features of the molecular weight distributions (MWDs) of polypropylene produced with TiCl4/MgCl4/C6H5COOC2H5/Al(C2H5)3as catalyst are investigated as functions of the polymerization time and the concentrations of Al(C2H5)3, C6H5COOC2H5and hydrogen. The MWDs are dependent upon the concentrations of Al(C2H5)3and C6H5COOC2H5, and are correlated with a change of the isotactic index of the produced polymers. In contrast, both MWD and the number‐average molecular weight M̄nremain unchanged during the polymerization from 5 s to 3 h. When hydrogen is added as a chain transfer reagent, M̄ndecreases as anticipated but the polydispersity index (M̄w/M̄n) is independent of the hydrogen concentration. The MWDs obtained with this supported catalyst are rather narrow (3≤ M̄w/M̄n≤8)and are represented by a log‐normal form or Wesslau equation, which is different from the MWDs (6≤ M̄w/M̄n≤20) obtained with the traditional TiCl3catalysts, which are represented by the Tung equation. Broadening of the MWD obtained with heterogeneous catalysts is also discussed. The constancy of M̄w/M̄n, independent of the hydrogen concentration leads to the important conclusion that non‐uniform surface sites on heterogeneous catalysts are responsible for the broadening of the MWD. A surface heterogeneity of the propagation rate constant,kp, is demonstrated on the basis of the kinetic data, concerning the effect of CO‐inhibition on the polymerization rate. A surface distribution function ofkp, capable of accounting for the broad MWDs, is presented and discussed in terms of a distribution of the activation energy for the propagation step.
Télomérisation du chlorure de vinylidène, 1. Réaction avec le tétrachlorure de carbone par catalyse rédox
Authors: Belbachir Mohamed , Boutevin Bernard , Piétrasanta Yves , Rigal Gérard
Published: April 2003

The redox telomerization of vinylidene chloride with carbon tetrachloride catalyzed by iron or copper salts was thoroughly studied. The DP of the telomers obtained vary from 1 to 100, roughly. The concentration of the reactants and the nature of the solvents exert some effect on the molecular weight distribution. The first adducts 1a – 1d (n = 1 to 4) were isolated and identified by NMR spectroscopy and viscosimetry.
Etude des propriétés électro‐optiques de i' adn par biréfringence électrique a faible champ, 2. Mécanismes d'orientation et de relaxation
Authors: Marion Christian , Perrot Brigitte , Roux Bernard , Bernengo Jean‐Claude
Published: April 2003

The electric birefringence of calf thymus DNA is measured at different low electric field strengths with rectangular and bipolar pulses as a function of concentration, ionic strength and molecular weight, and these results are interpreted in terms of orientation and relaxation mechanisms. The orientation of DNA is mainly due to an induced dipole, but the results reveal a slow induced moment, which is saturated, when low field strengths are applied. A well‐defined slow relaxation mechanism is demonstrated, which is attributed to the orientation of DNA as a whole. The long relaxation time decreases when high electric fields or high DNA concentrations are used, and the fact that the decay of the birefringence also contains short relaxation times does not reflect the polydispersity of the samples. The comparison between the molecular lengths determined from long relaxation times and the theoretical lengths of rigid cylinders shows an important coiling of DNA, when the fragments are longer than 110 – 120 nm.
Secondary structure of peptides, 14. FT‐IR and 13C NMR CP/MAS investigation of the helix stability of solid poly(L‐proline)s
Authors: Müller Detlef , Stulz Josef , Kricheldorf Hans R.
Published: April 2003

Primary amine and pyridine‐initiated polymerizations of L‐proline‐N‐carboxyanhydride (Pro‐NCA) at 20 or 100°C yield exclusively or predominantly 103‐helices. Only primary amine‐initiated polymerizations in 1,4‐dioxane at 100°C result in partial formation of 31‐helices. The stability of both 103‐ and 31‐helices against conformational transitions was investigated in various organic non solvents or salt solutions at 100 or 150°C. A 103 → 31 transition was only observed in protic non solvents such as formamide, water, or propionic acid, but not in alcohols. A 31 → 101 helix transition was observed in alcohols and most aprotic solvents but not in formamide, water, or propionic acid. Hence, it is concluded that the formation of 31 helices by primary amine‐initiated polymerizations in 1,4‐dioxane at 100°C is a kinetically controlled consequence of the reaction mechanism. The usefullness of 13C NMR CP/MAS spectra and Fourier‐Transform IR spectra for the quantitative analysis of composed secondary structures is compared and discussed.