bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultracentrifuge study of critically branched polycondensates, 4. Hinge point analysis and higher average molecular weights
Authors: Leonis Constantine G. , Suzuki Hidematsu , Gordon Manfred
Published: April 2003

Model polycondensates of 1,10‐decanediol and 1,3,5‐benzenetriacetic acid stabilised by means of diazodiphenylmethane and ketene are utilised to extend further our understanding of the critically branched state and to investigate possible contributions of the ultracentrifuge to the study of highly polydisperse macromolecules in non‐ideal, dilute solutions. By way of computerised curve fitting, the concentration gradient curve is obtained from its concentration profile in the ultracentrifuge cell. From this the weight average molecular weight M̄1 is calculated by the hinge point method. It is also confirmed that values of the two next higher moments of the molecular weight distribution, viz. M̄2/1 and M̄3/2 (i.e. Mz and Mz+1) can hardly be distinguished from infinity for these samples. Application of the hinge point method to systems of high polydispersity is found both theoretically and experimentally to furnish M̄1 after a dual extrapolation of the measured M̄ against the generalised speed parameter λ and the initial concentration c0. It is found theoretically that for estimation of the higher molecular weight moments, plots of M̄ M̄ and M̄ M̄ M̄ (not merely M̄ and M̄) must be extrapolated against the same variables, i.e. λ and c0. The quantitative results thus obtained are discussed in the context of previous results on these materials. They are compared with the classical theory for random f‐functional polycondensates and statistical cut‐off effects on the high molecular weight tail of distribution are assessed.
Synthese und eigenschaften einiger höhergliedriger cyclischer ätheracetale
Authors: Albrecht K. , Fleischer D. , Rentsch C. , Yamaguchi H. , Schulz R. C.
Published: April 2003

Optimized syntheses of 1,3,6,9‐tetraoxacycloundecane (2), 1,3,6,9,12‐pentaoxacylotetradecane (3), and 1,3,6,9,12,14,17,20‐octaoxacyclodocosane (4) as well as some physical and chemical properties and the proof of structure are reported.
Polymere aus Nitrilen, 6. Anionische Polymerisation von Fumaronitril. Isomerisierung von Fumaronitril zu Maleonitril
Authors: Helling Günter , Wöhrle Dieter
Published: April 2003

The oligomer of fumaronitrile 3, obtained by anionic polymerisation of fumaronitrile with butyllithium, is able to isomerise fumaronitrile to maleonitril. Kinetics and thermodynamics are examined and a model for the mechanism is proposed.
Crystallization of polypeptides in the course of polymerization, 7. Crystallization of poly(γ‐methyl‐L‐glutamate), poly(γ‐benzyl‐L‐glutamate) and poly(β‐benzyl‐L‐aspartate)
Authors: Kōmoto Tadashi , Kim Kea Yong , Kawai Tohru
Published: April 2003

Heterogeneous polymerizations of γ‐methyl‐L‐glutamate N‐carboxy anhydride (NCA), γ‐benzyl‐L‐glutmate NCA, and β‐benzyl‐L‐aspartate NCA were carried out using butylamine as initiator in acetonitrile at 30°C. The oligomer chains formed in the beginning of the polymerization crystallized into the antiparallel β‐form and thereafter the α‐helical chains grew from the active sites of the β‐chains. The polymerization of γ‐methyl‐L‐gultamate NCA proceeded to 100% conversion and accordingly gave rise to high molecular weight poly(γ‐methyl‐L‐glutamate). The polymerizations of γ‐benzyl‐L‐glutamate NCA and β‐benzyl‐L‐aspartate NCA stopped at 54% and 16%, resp. The levelling‐off of the conversion at such low values, in spite of the α‐helical chain growth, may be due to the occlusion of the active chain ends of the resultant poly(γ‐benzyl‐L‐glutamate) and poly(β‐benzyl‐L‐aspartate) into the crystals. It was concluded that the interlamellar crystallization was induced by the intermolecular interaction between the benzyl groups of the polymer side chains, giving rise to the occlusion of the active growing chain ends into the interstices of the crystal formed during the polymerization.
Bestimmung der geschwindigkeitskonstanten und der effektivitäten beim zerfall von 2,2′‐azoisobutyronitril in styrol, N‐vinyl‐2‐pyrrolidon und methylmethacrylat
Authors: Braun Dietrich , Quella Ferdinand
Published: April 2003

The decomposition rate constants kd of initiators can be determined by a new method directly in monomers as solvents. If a suitable inhibitor is added to a monomer mixture with the initiator the latter decomposes nearly without monomer conversion. The initiator concentration—after the inhibitor is consumed—can be found by means of the dilatometrically determined polymerization rate after the induction period. The functional connection between polymerization rate and initiator concentration found without inhibitor is used as a calibration curve for that purpose.

The dilatometrical measurements were made in the monomers styrene and N‐vinyl‐2‐pyrrolidone using 2,2′‐azoisobutyronitrile (AIBN) as initiator and p‐quinone as inhibitor. The following decomposition rate constants were found: kd=1,52 · 10−5 S−1 (styrene) and kd=1,62 · 10−5 S−1 (N‐vinyl‐2‐pyrrolidone), which is in agreement with literature values.

Initiator efficiencies f were calculated: f=0,46 (styrene), f=0,47 (N‐vinyl‐2‐pyrrolidone). In methyl methacrylate (MMA) 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) was used as inhibitor. Under certain conditions the product kdf can be calculated from the consumption rate of DPPH. The value found in MMA (kdf=3,7 · 10−6 s−1) is lower than that reported in literature (6,45 · 10−6 s−1).
Second virial coefficient of three‐block copolymers
Authors: Sikora A.
Published: April 2003

The two leading terms in the perturbation series expansion of the second virial coefficient A2 have been derived for a three‐block copolymer. The theoretical dependences of second virial coefficients on composition of a two‐block copolymers AB, b three‐block copolymers ABA and c mixtures of two homopolymers A and B have been compared at low values of the excluded volume parameters zA, zB and zAB. It follows from these calculations that with increasing thermodynamic quality of the solvent (with respect to both homopolymers) the effect of repulsive interaction between unlike segments of types A and B on the second virial coefficient of the copolymer decreases. The applicability of perturbation series to block copolymers is discussed.
Investigations on the mechanism of radiation induced crosslinking in ethylene‐propylene‐diene terpolymers
Authors: Geissler Wolfgang , Zott Hansjörg , Heusinger Helmut
Published: April 2003

The radiation induced crosslinking, double bond consumption, and radical formation of ethylene‐propylene‐copolymers (EPM) and ethylene‐propylene‐diene terpolymers (EPDM), containing either 5‐ethylidene‐2‐norbornene or dicyclopentadiene as the diene component, were investigated. The diene content was found to increase crosslinking as well as chain scission, 5‐ethylidene‐2‐norbornene being more efficient than dicyclopentadiene. The ESR‐spectra of EPM and EPDM at −196°C are almost identical, showing alkyl radicals corresponding to the ethylene and propylene component. At −50°C in EPDM allyl type radicals characteristic of 5‐ethylidene‐2‐norbornene, 6, and dicyclopentadiene residues, 4, are detected. Based on the results a mechanism for radiation induced crosslinking in EPDM is proposed.
Coupling reactions between polystyrene containing acyl chloride endgroups and poly(vinyl acetate) containing amino groups at the chain end or along the chain
Authors: Ikada Yoshito , Maejima Kazuo , Iwata Hiroo
Published: April 2003

Polystyrene (PS) and Poly(vinyl acetate) (PVAc), both carrying one terminal acyl chloride group, were synthesized by radiation‐polymerization in the presence of trichloroacetyl chloride, a chain transfer agent, and the acyl chloride groups of PVAc were converted to amino groups by reacting with excess ethylenediamine. Partial acetalization of poly(vinyl alcohol) with aminoacetaldehyde followed by acetalation of the remaining hydroxyl groups in the polymer yielded PVAc having a number of pendant amino groups distributed along the main chain. Condensation coupling reactions between the acyl chloride and amino groups were carried out in chloroform at room temperature to yield PS‐PVAc diblock copolymers and PVAc‐PS graft copolymers with many branches of PS. The pure copolymers were isolated from the reaction products by extraction and then characterized by determining chemical compositions and number‐average molecular weights.
Synthesis of Nε,N′ε‐(pyromellitoyl)dilysine and its copper (II) chelate polymer
Authors: Yang Chin‐Ping , Lin Tzu Fang , Iwakura Yoshio
Published: April 2003

Synthesis of Nε,N′ε‐(pyromellitoyl)dilysine (8) was carried out by reacting L‐lysine with dimethyl pyromellitate (6) followed by thermal imidation. The obtained product 8 was reacted with Cu2+ ions to form a light blue chelate polymer (9). Model compounds, Nε‐phthaloyllysine (4) and its copper chelate complex 5, were also synthesized by a similar process for comparison. IR spectra, optical and solubility properties of the monomer and its chelate polymer together with their corresponding model compounds were investigated. The thermal stability of chelate polymer 9 in acid solution of different pH value were also investigated.
Optimization of solution fractionation of poly(vinyl acetate)
Authors: Klein Joachim , Werner Michael
Published: April 2003

The theoretical assumptions to understand the elution mechanism of the discontinuous solution fractionation and complete elution method could be confirmed for the system poly(vinyl acetate)/butyl acetate/cyclohexane. In this case the process of complete elution, however, can only be carried out with an unfavorable high consumption of time and material. The complete elution method with all its advantages can be preserved, if the process is carried out as multistage process with a limited number of discontinuous steps. By means of such a multistage procedure improved separation results were achieved compared with the conventional single stage procedure. Furthermore some results are given which show a decrease of the separation effect of solution fractionation due to procedural limitations.
Kinetik von Copolymerisationen, 2. Dilatometrische untersuchungen der Copolymerisationen von N‐vinyl‐2‐pyrrolidon, Styrol und Methylmethacrylat
Authors: Braun Dietrich , Disselhoff Gabriele , Quella Ferdinand
Published: April 2003

The copolymerizations of N‐vinyl‐2‐pyrrolidone/styrene and N‐vinyl‐2‐pyrrolidone/methyl methacrylate—both systems with extremely different reactivity ratios—have been investigated in a recording dilatometer equipped with a thermo‐couple. The shrinkages of the systems can be described by the theory of Wittmer. The necessary values for the homopolymerizations as well as the binary reactivity ratios have been determined. The shrinkages have been verified independently by density measurements.
The effect of externally applid stresses on the structure of an ethylene‐rich EPDM terpolymer
Authors: Preedy John E. , Wallis Susan , Wheeler Ernest J.
Published: April 2003

Structural changes in an ethylene‐rich ethylene‐propylene‐diene terpolymer (EPDM) were studied as a function of applied external stress. From its initial unstretched value of 15%, the terpolymer crystallinity increased to 73% at a tensile strain of 225%. X‐ray diffraction patterns showed that, when stretched, the terpolymer assumed a hexagonal structure and an increase in the until cell a‐dimension occurred. A fibre texture developed with the lamellae inclined to the tensile axis.
Melting temperatures and enthalpies of polyethers: Poly(hexamethylene oxide)
Authors: Marco Carlos , Bello Antonio , Fatou José Gomez
Published: April 2003

An experimental study is reported of the dependence of the melting temperature Tm on the crystallization temperature Tc for molecular weight fractions of poly(hexamethylene oxide) in the range from Mn=2260 to Mn=35 500, with attention to the level of crystallinity.

It has been found that for the highest molecular weight fraction, at low levels of crystallinity, the extrapolated linear relation Tm vs. Tc yields an equilibrium melting temperature of 346,5K in very good accord with theoretical expectations. Moreover, the behaviour and theory for low‐molecular‐weight fractions is analyzed.

The enthalpy of fusion for poly(hexamethylene oxide) has been determined from two kinds of experiments: by measuring calorimetrically the apparent heat of fusion at different levels of crystallinity, and by using the polymer‐diluent method in decahydronaphthalene and 1,2,3,4‐tetrahydronaphthalene. The enthalpy of fusion was found to be 54–57 cal/g (=226–238J/g).
Strukturaufklärung der bei der Addition von 2‐Cyano‐2‐propylradikalen anp‐Tolyl‐ und 4‐Cyclohexylphenyl‐methacrylat entstehenden Produkte mittels1H NMR‐ und Massenspektren
Authors: Kämmerer Hermann , Pachta Jiri , Ullner Helmut
Published: April 2003

The chromatographically pure products, gained on the suppression of polymerisation ofp‐tolyl or 4‐cyclohexylphenyl methacrylates (1, 2) by a great excess of 2‐cyano‐2‐propyl radicals, could be isolated in a total yield of 95 to 100%. The structure of these products was established by1H NMR and mass spectroscopy. There arep‐tolyl or 4‐cyclohexylphenyl 4‐cyano‐2‐(2‐cyano‐2‐propyl)‐2,4‐dimethylvalerate (1a, 2a),p‐tolyl or 4‐cyclohexylphenyl 2‐(2‐cyano‐2‐methylpropyl)acrylate (1b, 2b),p‐tolyl or 4‐cyclohexylphenyl 4‐cyano‐4‐methyl‐2‐(2‐cyano‐2‐methylpropyl)valerate (1c, 2c),p‐tolyl or 4‐cyclohexylphenyl 4‐cyano‐2,4‐dimethylvalerate (1d, 2d), andp‐tolyl or 4‐cyclohexylphenyl 4‐cyano‐2,4‐dimethyl‐2‐pentenoate (1e, 2e(2f)). It is possible to give a scheme of reactions on the suppression of the radical polymerisation.
Photogalvanic effect of thin‐layer photocells composed of thionin‐polymer/Fe(II) systems
Authors: Shigehara Kiyotaka , Sano Hiroshi , Tsuchida Eishun
Published: April 2003

Two types of thionin (Th)‐polymers were prepared and their characteristics in the photogalvanic effects were studied by the use of thin‐layer photocells. One type of the polymers being soluble in methanol was somewhat cross‐linked by Th nuclei, and was cast on a water containing (Fe(II) solution) membrane between SnO2 and Pt electrodes. This membrane type thin‐layer photocell generated larger photo‐induced electricity than the similar thin‐layer photocell composed of the corresponding monomeric Th/Fe(II) solution, the reason of which was considered to be due to the electrostatic effect of cationic sites incorporated into the polymers. Another type of polymers was used as water‐containing (Fe(II) solution) gels, and the thin‐layer photocells composed of them generated a very small photo‐induced electricity due to the strong steric hindrance of entangled strands, which should decrease the possibility of the electrode reaction.
Cyclic oligomers in the cationic polymerization of 3,3‐dimethyloxetane
Authors: Bucquoye Marc , Goethals Eric J.
Published: April 2003

The formation of cyclic oligomers in the cationic polymerization of 3,3‐dimethyloxetane (1) was investigated. By means of gas chromatography coupled with mass spectroscopy, cyclic oligomers from tetramer up to nonamer (2a–f) were detected in decreasing concentration. The oligomer/polymer ratio at complete monomer consumption changes with the initiating system used. This ratio is not influenced by the initiator concentration but it increases with decreasing monomer concentration. It is proposed that the cyclic oligomers are formed by reaction of the monomer with macrocyclic oxonium ions of type 5 which in turn are formed by an intramolecular (temporary) termination reaction. The high preference to form cyclic tetramer is discussed in terms of the preferred polymer backbone conformation. In the polymerization of oxetane, cyclic tetramer is the most important oligomer, but, contrarily with previous reports, higher oligomers were also found to be present.
The formation of poly(phenylene sulfide)s and the substituent effect in reactions of substituted chlorobenzenes with sulfur
Authors: Hortling Bo , Lindberg J. Johan
Published: April 2003

The reactions of six substituted chlorobenzenes with sulfur were investigated, and the results were compared with the results of earlier investigations in which sodium carbonate also took part in the reactions. The effect of the amount of chlorine and of the different substituents on the reaction mechanism is discussed. The approximate structures of the cross‐linked substituted poly(phenylene sulfide)s are also given.
Additive effect of poly(ethylene oxide), 2. An acceleration effect of poly(ethylene oxide) in a williamson reaction
Authors: Hirao Akira , Nakahama Seiichi , Takahashi Mitsuru , Yamazaki Noboru
Published: April 2003

The additive effect of poly(ethylene oxide) (PEO) in the Williamson reaction between sodium phenolate and butyl bromide was investigated. Under certain conditions a remarkable rate acceleration by PEO was observed in this reaction, which is explained by the fact that a cooperative coordination of oxygen atoms of PEO with metal cations promotes ion dissociation. The relationship between the formation of a PEO‐sodium phenolate complex and the reaction rate, and also the dependency of the reaction rate on the molecular weight of PEO were examined.
Über die copolymerisation von (3‐vinylphenylazo)‐methylmalonodinitril mit styrol 7. Mitteilung über azo‐initiatoren
Authors: Kerber Robert , Nuyken Oskar , Dorn Maximilian
Published: April 2003

(3‐Vinylphenylazo)‐methylmalonodinitrile (2) was copolymerized with styrene up to high conversion giving no remarkable change in the monomer composition. The reactions were carried out in emulsion at 5°C, in bulk at 50°C, and in solution at 60°C. The azo compound displays not only the properties of an initiator (thermolysis) and monomer (vinyl group), but also the behaviour of a retardation reagent (azo‐function) explaining the decrease of polymerization rates and of molecular weights with increasing amounts of azo compound.
Tetraaza[14]annulen‐derivate und ihre vorstufen, 3. Katalyse, halbleitereigenschaften und thermostabilität der metallkomplexe
Authors: Müller Reinhardt , Wöhrle Dieter
Published: April 2003

The use of low molecular weight, bicyclic, and polymeric tetraaza[14]annulene metal complexes 1–5 of copper(II), cobalt(II), iron(II), and nickel(II) as oxygen activating catalysts in the oxidation of ethylbenzene to acetophenone was examined. In addition semiconducting properties and thermal stabilities of these complexes were investigated.
An automatically controlled reaction vessel suitable for the kinetic investigation of polymerization processes with half life periods of 2 seconds and greater
Authors: Warzelhan V. , Löhr G. , Höcker H. , Schulz G. V.
Published: April 2003

A reaction vessel automatically controlled by magnetic valves is described which allows kinetic measurements of reactions with half lives t1/2≥2s by gravimetric determination of the conversion. Thus, it covers the gap between the flow tube and the conventional reaction vessel.

The influence of mixing time and filling time on the molecular weight distribution of an anionically prepared polymer is discussed.
Kinetic studies of the anionic polymerization of methyl methacrylate in tetrahydrofuran with Na+ as counter ion, using monofunctional initiators
Authors: Warzelhan V. , Höcker H. , Schulz G. V.
Published: April 2003

A newly designed automatically controlled stirred reactor suitable for kinetic measurements of reactions with half lives ≥2s has been applied to follow the anionic polymerization of methyl methacrylate in THF with Na+ as a counter ion in the presence of an excess of NaB(C6H5)4.

As initiators were used: benzylsodium reacted with α‐methylstyrene (I), fluorenylsodium (II), and 9‐methylfluorenylsodium (III). With I the initiation is fast as compared with the polymerization reaction which is first order in monomer concentration. Within the range of −50°C to −100°C an almost unperturbed “living” polymerization is observed. The Arrhenius plot of the rate constants results in a straight line with activation energy Ea = 4,4kcal·mol−1 (= 18kJ·mol−1) and frequency exponent A = 7,0.II and III are slow initiators, II giving rise to side reactions because of the “acidic” proton in 9‐position after initiation, III exhibiting a rate constant of initiation ki = 1l·mol−1·s−1 at −72°C. The termination reaction is becoming increasingly important with increasing temperature and seems to be a unimolecular reaction with Ea,t = 11,5kcal·mol−1 (= 48 kJ·mol−1) and At = 10. Since the basic feature of the reactor is the possibility of drawing samples, polymers from each state of the reaction were available to be investigated also with respect to their tacticity. The monomer addition was shown to follow Bernoullian statistics. A structure of the “living” end being in harmony with the results observed is discussed.
Synthesis of a polycarbonate directly from carbon dioxide, alkali metal diolates and α,ω‐dihalo compounds
Authors: Soga Kazuo , Toshida Yomishi , Hosoda Satoru , Ikeda Sakuji
Published: April 2003

A detailed study was carried out on the new synthesis of poly[oxycarbonyloxy‐(1,4‐cyclohexylene)oxycarbonyloxymethylen‐1,4‐phenylenemethylen] (3) from 4‐bromomethylbenzyl bromide (1), dipotassium 1,4‐cyclohexanediolate (2) and carbon dioxide by using a variety of crown ethers as catalysts, which has recently been found by the present authors. Crown ethers having an 18‐member‐ring showed the best catalytic property of the various crown ethers, and the reaction was conducted in various solvents at 40–120°C by using 1,4,7,10,13,16‐hexaoxacyclooctadecane (18‐crown‐6 ether). A maximum yield with the highest molecular weight was obtained from the reaction at 100°C in dioxane solvent. In addition, as result of a kinetic study a plausible mechanism could be proposed. Similar reactions were also carried out with dipotassium and disodium 1,4‐phenylenedimethanolate (6a, b) and dipotassium 4,4′‐isopropylidenediphenolate (7) in place of 2.
Photoredox polymer with incorporated thionine and alkylenepolyamine capable of inducing photopotential
Authors: Kaneko Masao , Sugai Makio , Yamada Akira
Published: April 2003

A new type of photoredox polymer with incorporated thionine, (7‐amino‐3H‐phenothiazin‐3‐iminium chloride). (TH) and alkylenepolyamine groups was prepared by the reaction of poly(acrylic acid) with TH and alkylenepolyamines such as ethylenediamine (en), tetraethylenepentamine (3,6,9‐triazaundecane‐I,II‐diamine), (tetraen) and poly(iminoethylene). The photoredox polymers were able to induce photopotential in aqueous solution in the absence of any other redox reagents. The polymers from TH with on and with tetraen induced photopotentials of 180 mV and 167 mV, respectively. The photopotential of the former system was much higher than that of the system, TH/en. The induced photopotential of the polymer systems did not depend so much upon the mole ratio [en]/[TH] of the pendent groups, while the photopotential of the TH/en system was strongly dependent upon [en]/[TH]. Effects of the polymer structure were discussed.
Optimization of solution fractionation of poly(vinyl chloride)
Authors: Klein Joachim , Schriever Eckhard
Published: April 2003

The optimization of solution fractionation of poly(vinyl chloride) (PVC) is described with regard to the variation of several parameters. The best separation efficiency is obtained by a single‐step discontinuous solution fractionation at the following conditions: solvent: cyclohexanone (CHN); nonsolvent: ethylene glycol (EG); temperature: 130°C, isothermal; contact‐time: 2 h per fraction; amount of polymer: 2 mg/g support (glass beads). An essential improvement with respect to the separation of high molecular weight species can be achieved, applying a re‐deposition method of the polymer remaining in the column after half of the fractionation steps. This diminishes the unfavorable formation of a molecular weight‐ and concentration gradient along the column, occurring during fractionation. The optimally controlled single‐stage discontinuous solution fractionation of PVC turns out to be superior to multistage processes. This is attributed to the very critical problem of formation of insoluble microcrystalline aggregates with increasing duration of stay of the polymer in the column. The efficiency of the fractionation technique can be established by the characterization of fractions (center fractions: M̄w/M̄n < 1.1) and by confirmation of small differences in molecular weight distributions, shown by other methods.
Effect of polymer matrix on the cis‐trans isomerization of azobenzene residues in bulk polymers
Authors: Eisenbach Claus D.
Published: April 2003

Several acrylates and methacrylates were copolymerized with two 4‐aminoazobenzene methacrylic derivatives. The photochemical and thermal cis‐trans isomerization about the azolink was investigated in the bulk polymers. All the copolymers show photochromic behaviour without fading; the photostationary states upon irradiation with UV‐light of the appropriate wavelengths were similar in bulk and in solution. The thermal cis‐trans isomerization follows simple first order kinetics in the rubbery specimens as in solution. Below the glass transition temperature Tg, the isomerization can only be described by two simultaneous first order reactions. Depending on the conditions of irradiation and on the reaction temperature, a portion of the azoaromatic compound reacts anomalously fast. The temperature dependence of the relaxation time of the isomerization reaction in all the polymer films investigated can be represented by a single WLF‐type graph; the corresponding Arrhenius plot is curved above Tg. The findings are interpreted by considering the effects of the free volume and of the chain segmental mobility on the cis‐trans isomerization. A rotational and a translational relaxation mechanism is discussed for the normal and the anomalously fast reaction below Tg.
Surface photografting, 2. Modification of polypropylene film surface by graft polymerization of acrylamide
Authors: Tazuke Shigeo , Kimura Hitoshi
Published: April 2003

The hydrophobic surface of oriented poly(propylene) film (OPP) was modified to a hydrophilic one by a novel photo‐grafting procedure using acrylamide (AM) as monomer. A deoxygenated acetone solution containing AM and benzophenone (BP) or other sensitizers was brought into contact with OPP film and the reaction system was photoirradiated from the other side of the polymer film. Within a few minutes, surface photo‐grafting resulted. The influences of solvent, sensitizer, and additives revealed that the graft polymerization was initiated by hydrogen abstraction from the polymer surface by the triplet excited state of the sensitizer. IR Spectroscopy as well as ESCA measurements confirmed that the graft polymerization occurred on the film surface. The wettability of the grafted OPP film is discussed and correlated with the relative amount of surface grafting. The contact angle of untreated OPP film to water (101°) decreased to ≈40° after surface photografting. The drastic change of surface properties makes the practical application of the present technique feasible.
Dilute solution behavior of poly(vinylidene fluoride). Intrinsic viscosity and light scattering studies
Authors: Ali Sabz , Raina Autar K.
Published: April 2003

Light scattering and viscosity measurements of poly(vinylidene fluoride), (PVF2), were made in three solvents; namely, N,N‐dimethylacetamide (DMA), N,N‐dimethylformamide (DMF), and N‐methyl‐2‐pyrrolidone (NMP). The following relations between the intrinsic viscosity, [η], (in deciliters per gram) and the weight‐average‐molecular weight, M̄w, were obtained: [η] = 17,8·10−6 M̄(in DMA at 125°C), [η] = 31,7·10−6 M̄ (in DMF at 125°C) and [η] = 48,8·10−6 M̄ (NMP at 125°C). Treatment of the data by the method of Inagaki et al. indicates that the steric factor, σ, is 1,89, 1,65 and 1,60 in DMA, DMF, and NMP respectively. It is found that the root‐mean‐square radius of gyration of the chain measured by light scattering is in good agreement with the root‐mean‐square radius of gyration of the chain calculated by using the viscosity theory of Inagaki et al. The relations between the root‐mean‐square radius of gyration of the chain in the three solvents and the molecular weight obtained were as follows: 〈S̄2〉 = 2,95·10−1 M̄ (in DMA); 〈S̄2〉 = 8,13·10−2 M̄ (in DMF) and 〈S̄2〉 = 2,82·10−1 M̄ (in NMP). From the estimation of the second viral coefficient, A2, and the values of B (cf. Eq. (6)) obtained from viscosity data, it is concluded that the polymer chains are more extended in DMA than in DMF and NMP.
Copolymerization of 1‐vinylindol with maleic anhydride
Authors: Priola Aldo , Gatti Giuseppe , Santi Giuliano , Cesca Sebastiano
Published: April 2003

The formation of a charge‐transfer complex between 1‐vinylindole (1a) and maleic anhydride (MA) was detected by 1H NMR analysis, and the corresponding Keq was measured (Keq=0,251 mol in CDCl3 at 25°C). It could be shown that this complex can be involved both in the initiation and propagation steps of the 1a‐MA copolymerization by carrying out spontaneous copolymerization experiments and studying the influence of the feed composition on the conversion and [η] of the copolymer. The structure of the 1a‐MA copolymer, investigated by 13C NMR spectroscopy, was found to be complicated due to the formation of indoline rings along the chains by an attack of the propagating MA radical at position 2 in the indole ring. As a consequence an excess of MA, with respect to a 1:1 mole ratio of monomer feed, was usually found in the copolymer. The mechanism of the cyclization reaction was clarified by copolymerizing MA with 2‐methyl‐1‐vinylindole (1b), 3‐methyl‐1‐vinylindole (1c), or 2,3‐dimethyl‐1‐vinylindole (1d). An alternating copolymer with MA (mole ratio 1:1 of monomeric units), without irregularities, was obtained only by employing 1d as a comonomer.
Telechelic oligomers, 4. Synthesis of telechelic oligobutadienes by rh‐catalysis
Authors: Arlt Klaus , Heitz Walter
Published: April 2003

Polymerisation of butadiene using different Rh‐compounds, specially Rh(NO3)3, in allyl alcohol results in oligobutadienes with carbonyl functionality of 1 and hydroxyl functionality between 0—1. Under proper conditions telechelics are formed. Catalysis by Rh(NO3)3 can be accelerated by the addition of alcoholate or phosphine. The oligomers have exclusively 1,4‐trans‐structure. The combined use of alcoholate and triphenylphosphine results in oligobutadienes with 40% 1,4‐cis‐, 35% 1,4‐trans‐ and 25% 1,2 structure. Determination of the structure of isolated oligomers shows that both functional groups are incorporated by insertion of a complete allyl alcohol unit. According to the frequently found endgroup CH2C(CH2OH) … the incorporation of the hydroxyl group in the termination reaction by β‐hydride transfer is most likely. The carbonyl functionality is formed in the initiation step by hydride transfer from allyl alcohol to Rh. Analogous use of allyl chloride or allyl bromide results in telechelic oligobutadienes containing two halogens per molecule. but the structure of isolated oligomers shows that only one allyl halogenide unit is incorporated. The second terminal halogen is fixed to a butadiene unit. Again the characteristic group CH2C(CH2Cl)—… is found, suggesting a termination by β‐hydride transfer.
Polymerization of lactams, 29. On the initial stage of the activated anionic polymerization of 2‐pyrrolidone
Authors: Roda Jan , Kučera Otakar , KrálíčEk Jaroslav
Published: April 2003

The activated anionic polymerization of 2‐pyrrolidone in the initial stage was studied at 30–70°C in the range of 1–60 min. Potassium tert‐butoxide and N‐benzoyl‐2‐pyrrolidone were used as initiator and activator, respectively. It can be seen from the polymerization process that side reactions occur parallel to the fast propagation reaction.
Préparation et étude des propriétés chiroptiques de poly(tert‐butyloxiranne)s optiquement actifs
Authors: Sepulchre Maurice , Khalil Ahmed , Spassky Nicolas , Vert Michel
Published: April 2003

Optically active poly(tert‐butyloxirane)s of various molecular weights were prepared by polymerization of R(–)‐tert‐butyloxirane with different initiators or by stereoelective polymerization of the racemic monomer. Using identical conditions of polymerization (initiator, temperature etc.) it was found that the pure enantiomer polymerizes much faster than the racemic monomer. The chiroptical properties of the obtained polymers showed similarities in behaviour with those of a synthetized linear model molecule representative for a monomeric unit of the polymer. The enhanced optical activities of low molecular weight polymers were correlated with the presence of chelated hydroxylic end‐groups.
15N NMR spectroscopy 14. Neighboring residue effects in glycine‐containing polypeptides
Authors: Kricheldorf Hans R. , Hull William E.
Published: April 2003

The sequence polypeptides (Ala*‐Ala‐Gly)n, (Ala‐Gly*‐Gly)n, (Leu‐Gly‐Gly)n, (Val‐Gly‐Gly)n, and (Pro‐Gly‐Gly)n were synthesized by known methods, and their natural abundance 15N NMR spectra were measured in trifluoroacetic acid. These spectra were compared with those of other previously described sequence polypeptides and with the corresponding homopolypeptides. The spectra of all sequence polypeptides exhibit neighboring residue effects, so that glycine nitrogen atoms acylated by other χ‐(or ω‐)amino acids have chemical shifts different from that of the Gly‐Gly bond. These neighboring residue effects cannot be summarized or explained by simple rules; however, they are useful for the characterization of copolypeptides. Such an application was tested in the case of four sequence polypeptides consisting of isomeric sequences of identical monomeric units. All isomeric sequences can be distinguished from each other, and the observed shift effects could be related to the neighboring residue effects of other copolypeptides.
Synthese und halbleitereigenschaften von hemiporphyrazinartigen polymeren mit tetrathiafulvalen‐einheiten
Authors: Koßmehl Gerhard , Rohde Michael
Published: April 2003

Hemiporphyrazine type macroheterocycles with 2,2′‐bi‐1,3‐dithiolylidene (tetrathiafulvalene) units in the polymeric chains (3a–e) were obtained by reaction of 2,2′‐bi‐1,3‐dithiolylidenetetracarbonitrile (tetracyanotetrathiafulvalene) (1) with several diamines (2a–e). The black polymers were characterized by elemental analyses and IR spectra. Thermoanalytic measurements showed that decomposition starts without melting at temperatures > 300°C. The polymers were found to be polymeric organic semiconductors with activation energies of 0,6–1,4eV and electrical conductivities in the range from 10−14 to 10−10Ω−1.cm−1. In the case of the polymers 3a and 3b it was possible to obtain metal complexes (4a–b) by substituting the two hydrogen atoms inside the macroheterocyclic rings. Depending on the metal atoms the electrical conductivities were enhanced up to two orders of magnitude.
Polymerization of α,α‐disubstituted β‐propiolactones and lactams, 12. Properties and crystalline structure of poly(β‐propiolactam)s
Authors: Eisenbach Claus D. , Lenz Robert W. , Duval Michel , Marchessault Robert H.
Published: April 2003

A series of α,α‐disubstituted β‐propiolactams (substituted nylon 3 polymers) was prepared from non‐optically active lactams. Their thermal characteristics, densities, and x‐ray fiber diffraction patterns were recorded. One of the α‐substituents was always a methyl group while the other was either CH3, C2H5, n‐C3H7, or n‐C4H9. The melting point for the dimethyl substituted polymer was 268°C; the others were respectively 76, 74, and 72°C. X‐ray fiber diffraction data on all four samples yielded the same fiber repeat of ≈8,4 Å. A minimum energy based conformational analysis for the α,α‐dimethyl derivative indicates that two conformations correspond to this repeat, each of which is a 21 helix.
Crystallization of poly(L‐proline) in the course of polymerization
Authors: Kim Kea Yong , Kōmoto Tadashi , Kawai Tohru
Published: April 2003

The heterogeneous polymerization of L‐proline N‐carboxy anhydride was carried out in acetonitrile and benzene, using butylamine as the initiator. Polyproline I was formed in acetonitrile and polyproline II in benzene in the course of the polymerization. The conversion attained 99% and 66% after 1 week‐polymerization in acetonitrile and benzene, resp. Extended chain crystals were obtained by the polymerization in acetonitrile. On the other hand, poly(L‐proline) obtained by the polymerization in benzene gave aggregates into which many growing chain ends were occluded. The differences in the crystallization behaviour during the polymerization between the two different liquids may be due to the conformation of the resultant polymers. Polyproline I exhibits a cross‐section per chain of 0.709 nm2, whereas polyproline II shows only one of 0,386 nm2. The wider the cross‐section per chain the more the growing, active chain ends can react with the monomer, giving rise to a higher conversion. In contrast with the case of crystallization of such α‐helical chains as poly(L‐alanine) during polymerization, hexagonal lamellar crystals were formed.
Interferenzmikroskopische charakterisierung von faserstrukturen, 4. Zusammenhänge zwischen der farbstoffdiffusion und der faserstruktur beim färben von polyethylenterephthalat‐fasern mit dispersionsfarbstoffen
Authors: Kühnle Gerhard , Schollmeyer Eckhard , Herlinger Heinz
Published: April 2003

Concentration distributions of dyestuffs C. I. Disperse Red 60 and C. I. Disperse Blue 139 in microtomic cuttings of fibers of poly(ethylene terephthalate), (poly(oxyethyleneoxyterephthaloyl)) are discussed. An interpretation of the results in relation to order and orientation along the fiber radius by interferometric investigations gives informations about the diffusion process. It is shown, that the diffusion of dyestuffs in high polymers depends—in a complicated way—on fiber structure (as a function of the diffusion path), fiber history, and experimental conditions: C. I. Disperse Red 60 shows a lower diffusion rate at higher radial orientations, whereas the diffusion rate of C. I. Disperse Blue 139 does not depend on the radial dependence of these structure parameters.
Sequential homogeneity of copolymers
Authors: Georgiev George Stefanov
Published: April 2003

Using the finite Markov chains, a method for deriving the relations about the sequential homogeneity indexes for s‐component (s ≥ 2) copolymers is developed. The sequential homogeneity index for binary copolymers as proposed by Tosi and Catinella is proved to be a particular case of the sequential homogeneity index for s‐component copolymers as derived in the present paper. Moreover a method for determination of average lengths and composition of sequences, situated among every two arbitrarily chosen monomeric units is proposed. The sequential homogeneity indexes, the lengths and composition of the above‐mentioned sequences for ternary copolymers of styrene (M1), methyl methacrylate (M2) and acrylonitrile (M3) and quaternary copolymers of styrene (M1), methyl methacrylate (M2), acrylonitrile (M3) and vinylidene chloride (M4) are calculated as an illustration of the method developed.
Mechanism of the NCA polymerization 7. The primary and secondary amine‐initiated polymerization of β‐amino acid NCAs
Authors: Kricheldorf Hans R. , Mülhaupt Rolf
Published: April 2003

The reaction of β‐alanine N‐carboxyanhydride (β‐Ala NCA) (1) with various primary and secondary amines was investigated at room temperature. Three reaction products were found: poly(β‐alanine), β‐alaninamides, and N′‐substituted β‐ureidopropionic acids. The mole ratio of these reaction products depends on the reaction conditions, above all on the NCA/amine ratio, and on the nucleophilicity/basicity ratio of the amines. All amines with pKa‐values > 8,0, including the amino end‐groups of the growing chains, cause the formation of β‐isocyanatocarboxylate ions by deprotonation of the β‐NCAs, and thus, the formation of β‐ureidocarboxylic acids. If the chain ends are involved, this reaction sequence is a termination step, and it is this termination step which is responsible, for that high polymerization degrees (> 60) are not accessible by a primary or secondary amine‐initiated polymerization of β‐NCAs. The β‐ureidocarboxylic acid end‐groups are detectable in the 13C NMR spectra of the poly(β‐amide)s.
The influence of intermolecular interactions on the polymerization, 3. Radical polymerization of 1‐naphthyl methacrylate and 2‐naphthyl methacrylate in acetone and acetonitrile
Authors: Boudevska Hrissanta , Brutchkov Christo
Published: April 2003

Polymerizations of 1‐naphthyl methacrylate and 2‐naphthyl methacrylate in acetone and in acetonitrile were carried out in the presence of 2,2′‐azoisobutyronitrile at 55 and 60°C, respectively. The polymers precipitate during the polymerization. Poly(1‐naphthyl methacrylate)s are partly soluble in common organic solvents. The polymerization medium does not influence noticeably the intrinsic viscosity of the resulting polymers. The tacticity was determined by 1H NMR analysis after conversion of the poly(naphthyl methacrylate)s into poly(methyl methacrylate)s. Poly(naphthyl methacrylate)s obtained in acetone and acetonitrile have a higher content of isotactic triads than those obtained in solvents with low dielectric constants. The observed results correlate with the changes in the 1H NMR spectra of the monomers depending on the dielectric constants of the solvents.
15N NMR spectroscopy, 16. Stereospecificity and racemization in the course of the synthesis of (ε‐Aca‐D,L‐Ala‐D,L‐Ala)n
Authors: Kricheldorf Hans R. , Hull W. E.
Published: April 2003

H‐D,L‐Ala‐D,L‐Ala‐OH (3) synthesized from Boc‐D,L‐Ala‐OH and H‐D,L‐Ala‐OMe by means of ethyl 2‐ethoxy‐1,2‐dihydroquinoline‐1‐carboxylate was shown by 15N NMR spectroscopy to be a mixture of the L‐L and D‐D enantiomers. Using this racemic mixture N‐(6‐isothiocyanatohexanoyl)‐D,L‐Ala‐D,L‐Ala‐OH (1a) was synthesized and then polymerized in N,N′‐dimethylformamide at 120°C. The 15N NMR and 13C NMR spectra of the resulting polymer (ε‐Aca‐D,L‐Ala‐D,L‐Ala)n (2) demonstrate that the polymerization involved to a large extent racemization. The 15N NMR spectra taken in various solvents turned out to be ca. 5 times more sensitive to stereoisomerism than 13C NMR spectra. The solvents were found to have a strong influence on the chemical shift and on the line width.
The photochemistry of ring substituted polystyrenes, 5. Photolysis of poly(p‐amino) and poly(p‐nitrostyrenes)
Authors: Weir Neil A. , Milkie Terence H.
Published: April 2003

The short‐wave (λ = 254 nm) photochemistry of poly(p‐aminostyrene) (PPAS), and poly(p‐nitrostyrene) (PPNS) films was studied under high vacuum conditions (≈ 10−6 mbar) at 25°C. The principal reaction product in both cases was hydrogen, but both polymers also underwent coloration, crosslinking, and chain scission. Rates of chain scission and hydrogen formation were found to be considerably greater for PPAS, and these was attributed to the stabilizing effect of the p‐amino group (relative to that of the p‐nitro group) on the intermediate free radicals. The very high rate of crosslinking of PPAS would suggest the participation of the p‐amino group in crosslinking reactions.
Association of block copolymers in selective solvents 2. Viscosity, diffusion and light‐scattering measurements on hydrogenated poly(styrene‐isoprene) in trans‐decalin/decane mixtures
Authors: Mandema W. , Emeis C. A. , Zeldenrust H.
Published: April 2003

The association of a hydrogenated poly(styrene‐isoprene) block copolymer has been studied in mixtures of a selective (decane) and a non‐selective solvent (trans‐decalin). Viscosity, diffusion and light‐scattering studies were made within the temperature range of 25–100°C. Relatively small, compact micelles with a rather monodisperse distribution are found at low temperatures and high decane concentrations; very large, polydisperse associates are formed at intermediate decane concentrations and also at increasing temperature from the compact micelles prior to complete dissociation. These large particles have no particular effect on the inherent viscosity, which shows a gradual, continuous decrease as the polymer passes from the associated to the dissociated state. The association also gives rise to drastic changes in the UV absorption of the polystyrene part of the polymer. Kinetic experiments indicate a time scale of the order of ten seconds for the association‐dissociation transition.
Relationships between linear expansion factors of polymer coils from viscosity and light scattering
Authors: Chiantore Oscar , Guaita Marino
Published: April 2003

The validity of several relationships which have been explicitly or implicitly proposed to describe the dependence of the linear expansion factor αη, as obtained from viscosity data, on the linear expansion factor αs, as given by light scattering measurements, was tested by applying standard statistical procedures to 133 pairs of αη and αs values. The results so obtained show that the simple identity αη = αs does not disagree with the experimental data. In limited ranges of αη values, however, a better fit is given by two relationships obtained by combining a theoretical equation by Tanaka et al., relating αs and the excluded volume variable z, with the empirical dependence between αη and z, as observed by the same authors. Following a similar empirical approach, a new realtionship is derived which describes the dependence of αη on αs, in the whole range of αη values, better than the identity; nevertheless the αη values calculated from αs through such a new relationship are always very close to αs, the differences being most probably smaller than the errors affecting the experimental determination of the expansion factors.
Head‐to‐head polymers, 14. Thermal degradation of head‐to‐head and head‐to‐tail polystyrenes and poly(vinylcyclohexane)s
Authors: Lüderwald Ingo , Vogl Otto
Published: April 2003

The thermal degradation behavior of head‐to‐head (H‐H) and head‐to‐tail (H‐T) polystyrenes and poly(vinylcyclohexane)s has been investigated by direct pyrolysis in a mass spectrometer. Both H‐H and H‐T isomers show only small differences in their initial temperatures of decomposition but remarkably different degradation processes. Whereas H‐T polystyrene decomposes in accordance with earlier investigations mainly by a radicalic depolymerization into the monomer and yields only a small amount of dimer and trimer, the H‐H polystyrene shows no unzipping and only a statistic degradation into oligomeric styrenes. The formation of stilbene is a diagnostic reaction of H‐H polystyrene. The pyrolysis‐mass spectra of H‐H and H‐T poly(vinylcyclohexane)s are more similar than those of the polystyrenes but the favored thermal cleavage between the two tertiary carbon atoms or next to the tertiary carbon atoms of the polymer backbone chain leads to some characteristic fragments, e.g. 1,3‐dicyclohexylpropene from the H‐T and 1,2‐dicyclohexylethane from the H‐H polymer.
Effect of pressure on the sedimentation coefficient in dilute and semi‐dilute solutions of polyisobutylene in octane
Authors: Nyström Bo , Roots Jaan
Published: April 2003

Sedimentation measurements over the concentration interval 3–16 kg. m−3 and the pressure range 0,1–5 MPa are reported for the system polyisobutylene/octane. The pressure influence on the sedimentation process was found to be less pronounced at higher than at lower concentrations.
Gelchromatographische refraktionierung, molekulargewichtsabhängigkeit der axialen dispersionsfunktion
Authors: Berger Knud C.
Published: April 2003

The knowledge of axial dispersion is necessary for the determination of molecular weight distributions from gel permeation chromatograms. This work deals with the determination of the axial dispersion function and its dependence on the molecular weight using refractionation method. The results of a number of fractionated and unfractionated samples of polystyrene reveal that peak dispersion in GPC arises mainly from diffusion in the stationary phase on the basis of the theoretical expression proposed by Kubin.