bluuebunny/crossref_metadata_2025 huggingface dataset:
13C‐Relaxationsuntersuchungen zum Einfluß des Lösungsmittels auf die Kettenbewegung von Polystyrol
Authors: Gronski Wolfram , Murayama Nobumichi
Published: April 2003

Temperature dependent measurements of 13C spin lattice relaxation times and of nuclear Overhauser enhancement factors were carried out for atactic and isotactic polystyrene in tetrahydrofuran and for atactic polystyrene in 1,4‐dioxane. The analysis of the relaxation data by means of a Cole‐Cole distribution of correlation times confirms the additivity of intramolecular and solvent viscosity dependent activation energies. For atactic and isotactic polystyrene the same intramolecular activation energy of 21 ± 5kJ/mol is obtained for the segmental motion. A comparison with 13C relaxation measurements of other authors shows that the intramolecular activation energies and the anisotropy of the segmental motion are increasing simultaneously by changing the solvent from toluene over pentachloroethane to tetrahydrofuran. Based on the experimental findings the chain motions in polystyrene are interpreted as diffusion controlled processes in the hindering potential of the CC bonds of the chain backbone which is modified by conformation dependent interactions between phenyl groups and solvent molecules.
Molecular weight and chain length distribution of native poly(β‐1,4‐D‐mannose) from cell walls of the alga codium
Authors: Marx‐Figini Marianne , Coun de Matus María
Published: April 2003

Poly(β‐1,4‐D‐mannose)

Commonly named mannan.

was isolated from cell walls of the alga Codium decorticatum by methods proved to preserve its native degree of polymerization. The intrinsic viscosities obtained on native mannan nitrates from algae harvested in different years possess values [η]≈440ml.g−1 with a maximum deviation of 9%, independent of the year of harvest and the age of the cell walls. Osmotic measurements on one of these samples resulted DPn = 375. Fractionation experiments on the same material revealed a nearly monodisperse chain length distribution. The notable independence of the degree of polymerization from the growth conditions and the age of the plants together with its monodispersity let assume a biopolymerization mechanism which is controlled genetically and not by the time of synthesis.
Self‐quenching interaction between ferrocene units in photooxidation‐reduction sensitized by copolymers of 1‐ferrocenylethyl methacrylate
Authors: Nakahira Takayuki , Minami Chiyo , Iwabuchi Susumu , Kojima Kuniharu
Published: April 2003

Copolymers of 1‐ferrocenylethyl methacrylate (FEMA) with styrene (St) and methyl methacrylate (MMA) were prepared, and their photosensitizing capability with respect to oxidation‐reduction between L‐ascorbic acid and Fast Red A was examined in dimethylformamide. With both types of copolymers, the higher the FEMA content, the lower the relative quantum yield of the sensitization. The observed decrease in the relative quantum yield was interpreted in terms of Perrin's model of static quenching interaction between excited and near‐by ground‐state ferrocene units. The mean sequence length of FEMA in the polymer was found to be an appropriate parameter for the local ferrocene concentration with respect to the polymer. Both energy migration and quenching interaction were thus suggested to occur among nearest‐neighbor ferrocene units along the polymer chain; the latter prevails over the former. It was also suggested that the ester carbonyl group of MMA units interacts with near‐by excited‐state ferrocene units.
Catalytic properties of 4(5)‐imidazolylmethylated poly(vinyl alcohol) in the hydrolysis of p‐nitrophenyl acetate
Authors: Kida Masaaki , Nakano Hidehiko
Published: April 2003

The catalytic hydrolysis of p‐nitrophenyl acetate (PNPA) by 4(5)‐imidazolylmethylated poly(vinyl alcohol) (IMPVA) was studied. When IMPVA (\documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm DP}} \approx 2000 $\end{document}, imidazolyl content: 2,7 mole‐%) was used as catalyst, the rate of catalytic hydrolysis showed substrate saturation phenomena and could be described by a Michaelis‐Menten kinetics with Km = 3,3 mmol·l−1 and kcat = 9,4·10−3 min−1. Km and kcat increased with increasing imidazolyl content in the IMPVA (imidazolyl content = 13,0 mole‐%, Km = 53 mmol·l−1 and kcat = 8,7·10−2 min−1). Addition of ethanol to the reaction mixture resulted in a decrease in Km and kcat (ethanol conc. = 50 vol.‐%, Km = 1,5 mmol·l−1 and kcat = 1,7·10−3 min−1). In the presence of boric acid, Km increased, while kcat varied in a complicated manner. The catalytic properties of IMPVA were found to be also affected by the degree of polymerization, and when an IMPVA of \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {{\rm DP}} \approx 500 $\end{document} with an imidazolyl content of 2,7 mole‐% was used as catalyst, substrate saturation phenomena were not observed.
Preferential solvation of poly(acrylic acid) and its sodium salt in water/dioxane mixtures: A comparison with poly(α‐L‐glutamic acid)
Authors: Morcellet Michel , Loucheux Claude
Published: April 2003

The preferential solvation of poly(acrylic acid) and its sodium salt in water/dioxane mixtures was studied. The comparison with results previously obtained on poly(χ‐L‐glutamic acid) indicates the preferential solvation of the latter polymer by dioxane is due to the existence of the peptide group in the polymer. The viscosimetric behavior of poly(acrylic acid) in water/dioxane mixtures is interpreted by the existence of water‐dioxane complexes with a definite stoechiometry.
Electric field effects in the polymerization of α‐methylstyrene
Authors: Akbulut Ural , Birke Ronald L. , Fernandez Jack E.
Published: April 2003

We here report the boron trifluoride diethyletherate initiated polymerization of χ‐methylstyrene in 1,2‐dichloroethane. With platinum foil electrodes and an applied electric field of 1–3kV/cm, the initial rate of disappearance of monomer is the same in the absence or presence of the electric field. The rate of formation of polymer at high conversions, however, decreases when the electric field is imposed. The NMR, UV absorption, and fluorescence spectra of the polymers are affected by the field, whereas the IR, ESCA spectra, and melting point of the polymer are unaffected by the field. To probe the reasons for these field effects, we obtained oxidation and reduction potentials of monomer, solvent, and initiator by polarographic or cyclic voltammetric methods. All the components of the system were easily reduced or oxidized. Also, when the anode and cathode were separated by a sintered glass disk, the amount of polymer formed in the anode compartment was greater than that in the cathode compartment. These results suggest that the observed electric field effects are due to electrochemical reactions rather than to the second Wien effect.
Kinetische und morphologische untersuchungen zur polymerisation von oxacyclischen monomeren im festen zustand, 3. Zur morphologie der bei der polymerisation von trioxan mit chemischen katalysatoren entstehenden polyoxymethylene
Authors: Muñoz‐Escalona Antonio
Published: April 2003

The nascent crystal structure and morphology of poly(oxymethylene) (POM) obtained from 1,3,5‐trioxane crystals, induced by gaseous chemical initiators, was studied in order to clarify the solid‐state polymerization mechanisms of this monomer. The polymerization starts at the surface of the monomer crystals and propagates towards its interior. The polymerization rate, therefore, depends on the size of the crystals and not on the initiator amount. Hexagonal fibrous crystals without a main orientation were obtained on the surface of the monomer crystal. These crystals orientated themselves along the c‐axis of the monomer, due to the polymerization propagation inside the crystals by simultaneous solid‐gas polymerization and crystallization mechanisms. The orientation depended on the reactivity of the initiator, the order being: BF3‐O(C2H5)2 > SnCl4 > H2SO4‐paraformaldehyde. The orientation was also improved by increasing the polymerization temperature, obtaining POM crystals similar to those found by radiation induced polymerization. At low polymerization temperature folded chain crystals were obtained similar to those encountered by solution polymerization according to crystallization succeeding polymerization mechanisms.
Diffusion of gases in cellulose triacetate
Authors: Patel V. M. , Patel K. C. , Patel R. D.
Published: April 2003

Diffusion data of helium, nitrogen, oxygen, and carbon dioxide through glassy cellulose triacetate were obtained and analyzed by the modified time‐lag technique of DiBenedetto and Paul. Thermodynamic data were evaluated and a probable mechanism for gaseous diffusion is discussed.
15N NMR spectroscopy, 10 Investigation on structure/shift relationships of nylon‐6,6 polyamides
Authors: Kricheldorf Hans R.
Published: April 2003

Series of polyamides were prepared from p‐phenylenediamine, and aliphatic α,ω‐diamines on the one hand, and fumaric acid, isophthalic acid, terephthalic acid, and aliphatic α,ω‐diacids on the other hand. The natural abundance 15N NMR spectra of these polyamides were measured in trifluoroacetic acid, and relationships between the chemical shifts and the structure of the monomer units are discussed. Increasing chain length of the aliphatic diamines results in increasing downfield shift of the diamines themselves and of the polyamides derived from them. No “γ‐effect” or similar deviations from the monotonic shift function are observed; however, the influence of the diacid residues on the chemical shift is less regular. The shifts of the homopolyamides are useful for assigning or predicting the shifts of copolyamides. The 15N NMR spectrum of the copolyamide “Trogamide T” is discussed.
Determination of initiation rate in the copolymerization of acrylonitrile with methyl methacrylate carried out in N,N‐dimethylformamide
Authors: Szafko Jerzy , Mańczyk Krystyna
Published: April 2003

Results of studies on the determination of the initiation rate of the copolymerization reaction of acrylonitrile with methyl methacrylate, initiated by 2,2′‐azoisobutyronitrile in N,N‐dimethylformamide at 60°C are reported. The inhibition method used was that involving the stable Banfield's radical (N‐[1,1‐dimethyl‐3‐(N‐oxidophenyliminio)butyl]‐N‐phenylaminyl oxide).

In the case of acrylonitrile an effect of a side reaction of initiation with the stable radical was observed along with a retarding effect due to inhibition reaction products.

In the homopolymerization of methyl methacrylate there takes place a slight effect from a side initiation reaction due to the Banfield's radical, the inhibition reaction products not influencing the further course of the polymerization reaction.

The overall contribution of the side initiation reaction changes in the copolymerization of acrylonitrile with methyl methacrylate for different comonomer mixtures with their composition, the actual changes being non‐additive. The initiation rate depends on the composition of the monomer mixtures and may be described by the following relation:

where Ri, AN=(8,20±0,15).10−7 mol.dm−3.s−1 and Ri, MM=(7,75±0,25).10−7 mol.dm−3.s−1.
Polycondensation d'acides α‐aminés par des systèmes iode‐phosphites en présence de pyridine ou d'imidazole
Authors: Le Guilly Lionel , Brack André , Spach Gérard
Published: April 2003

Polymerization of free α‐amino acids with a pair of reagents–an oxidizing agent (iodine) and a reducing agent (phosphonic acid esters)–was achieved in organic medium in the presence of pyridine or imidazole. A standard procedure leading to optically pure polypeptides with degrees of polymerization up to 50 could be established. Polymeric material was also obtained with a dipeptide as monomer. Some preliminary polymerizations with polyfunctional reagents such as poly(4‐vinylpyridine), cyclodiphosphites, or polyphosphites were performed.
Protected polyvinylamine fragments capable of liberation under mild conditions
Authors: Carpino Louis A. , Hettrich Gernot M. , Ringsdorf Helmut
Published: April 2003

The synthesis and polymerization of 2‐cyanoethyl N‐vinylcarbamate (3b) and of the corresponding 2‐trimethylsilylethyl isomer 3c are reported. The homopolymers 4b and 4c, derived from 3b and 3c, could be deblocked under mild conditions (ethanolamine for 4b and trifluoroacetic acid or tetraethylammonium fluoride for 4c) with essentially 100% unmasking of the amino function. Treatment of such unmasked amino groups in a copolymer derived from N‐vinyl‐2‐pyrrolidone and 3b with 4‐{4‐[bis(2‐chloroethyl)amino]phenyl}butyryl chloride (13) (chlorambucil chloride) gave the corresponding amide, a potential antitumor agent. Kinetic studies showed that fluoride ion cleavage of poly(2‐trimethylsilylethyl N‐vinylcarbamate) occurred at rates comparable to those observed for the low molecular weight analog 2‐trimethylsilylethyl N‐isopropylcarbamate (10).
The behaviour of poly(methacrylic acid) and poly(2‐hydroxyethyl methacrylate) in water/2‐chloroethanol mixtures
Authors: Carton Brigitte , Bottiglione Vincent , Morcellet Michel , Loucheux Claude
Published: April 2003

The viscosimetric behaviour and the preferential solvation of poly(methacrylic acid), (PMA, poly(1‐carboxy‐1‐methylethylene)) and poly(2‐hydroxyethyl methacrylate), (PHEMA, poly[1‐(2‐hydroxyethoxycarbonyl)‐1‐methylethylene]) in water/2‐chloroethanol mixtures were studied. The system PHEMA/water/2‐chloroethanol is a typical polymer/solvent/precipitant system in which 2‐chloroethanol is preferentially solvated in the whole range of solubility. On the contrary, the system PMA/water/2‐chloroethanol is a typical cosolvent system which exhibits the so‐called inverse adsorption. This difference is attributed to the more hydrophilic character of the carbonyl group in PMA.
Polymerization of 1‐vinylindole and its methyl derivatives. Structure of the polymers
Authors: Priola Aldo , Gatti Giuseppe , Cesca Sebastiano
Published: April 2003

The polymerization of 1‐vinylindole (1a) induced by free radical and cationic initiators is studied and the structure of the resulting polymers is elucidated by 13C NMR spectroscopy. Also 2‐methyl‐1‐vinylindole (1b), 3‐methyl‐1‐vinylindole (1c), and 2,3‐dimethyl‐1‐vinylindole (1d) are polymerized in order to understand the polymerization mechanism of this class of monomers. Radical polymerization affords a linear polyvinylic structure in the case of 1b and 1d, and cyclic indoline type structures in the case of 1a and 1c. Cationic polymerization gives linear structures for poly(1c) and poly(1d), but cyclic structures for 1a. Evidence is given that cyclization involves position 2 of the indole ring in the radical polymerization, and position 3 in the cationic polymerization. Five and six membered rings are formed, respectively. The indole ring was found to be unreactive, under the adopted conditions, in the linear radical propagation reaction.
Synthesis of polyamide‐sulfonamides by ring‐opening polyaddition of N,N′‐sebacoylbis(ethanesultam) with aliphatic diamines
Authors: Imai Yoshio , Hirukawa Horishi , Okuyama Kazuo , Ueda Mitsuru
Published: April 2003

The aminolysis of N‐benzoylethanesultam (1) was conducted as a model compound study and was found to give almost exclusively ring‐opened adduct. The ring‐opening polyaddition of N,N′‐sebacoylbis(ethanesultam) (5), synthesized from a sebacoyl chloride and ethanesultam (3), with aliphatic diamines in HMPT afforded a new class of polyamide‐sulfonamides having inherent viscosities of 0,1–0,8dl.g−1 in excellent yields. All of the polymers were soluble in polar aprotic solvents and some acidic solvents. These polymers began to decompose at around 300°C in air, as determined by TG.
Thermal polymerization of dihydro‐exo‐dicyclopentadienyl acrylate
Authors: Hatano Akira , Iwase Yoshiyuki , Toda Yoshihisa
Published: April 2003

The thermal polymerization of dihydro‐exo‐dicyclopentadienyl acrylate (DDA) (tricyclo[5.2.1.02.6]dec‐3‐en‐9‐yl acrylate) was carried out under nitrogen in the absence of any initiator to investigate the kinetics and mechanism for it. The polymerization rate was found to follow the equation: Rp=k[DDA]1.6. The rate was nearly the same as those obtained for the polymerization of other alkyl acrylates. The overall activation energy for the polymerization was determined to be 57,3 kJ/mol (13,7 kcal/mol). The kinetic data and the data obtained by spin trapping technique during the polymerization showed that the double bond of the acryl group was polymerized much faster than that of the cyclopentene ring to form the straight chain polymer and that the double bond of the cyclopentene ring began to polymerize to a small extent, at a stage where most of acryl groups were polymerized, to give some crosslinking structures.
Mechanism of the polymerization of hexamethylcyclotrisiloxane (D3) in the presence of a strong protonic acid
Authors: Chojnowski Julian , Wilczek Lech
Published: April 2003

The polymerization of hexamethylcyclotrisiloxane (D3) was studied in methylene chloride solution in the presence of trifluoromethanesulfonic acid as catalyst. The reaction occurs mostly by addition of monomer to the ends of growing molecular chains. However, an important role is played by cleavage of a siloxane bond in the monomer by acid or water as well as by reverse processes of silanol and/or +ylester end group condensation to siloxane linkages. The latter account for the formation of large amounts of cyclic products and for the coupling of linear chain fragments. They are also responsible for the regeneration of the catalyst leading to establishment of stationary concentrations of reactive species in the polymerization system.

The involvement of the above mentioned processes of condensation and siloxane bond cleavage contributes to a dramatic change in kinetics of the polymerization with introduction of water into the reaction system. In particular, the polymerization when carried out without water addition shows three interconnected features: 1 Strong acceleration of the rate with addition of small amounts of water to the system. 2 An apparent negative value of the activation energy. 3 Increase of the rate with decreasing initial concentration of the monomer. Above a certain level of water content the polymerization rate is only slightly dependent on the concentration of water. The energy of activation is 50 kJ/mol and the reaction is of 1st order in monomer, internally as well as externally.
Inverse problems in polymer characterization: Direct analysis of polydispersity with photon correlation spectroscopy
Authors: Provencher Stephen W.
Published: April 2003

A method is presented for inverting the Fredholm integral equations of the first kind that arise in many experimental determinations of molecular weight distributions of high polymers. The well known problems of instability and nonuniqueness are minimized by constraining the distribution to be the smoothest nonnegative one that is consistent with the data. Analyses of simulated photon correlation spectroscopy data show that good accuracy can be obtained for unimodal distributions and fair accuracy for certain bimodal ones, provided that systematic errors are kept below the random noise level. The method is completely automatic in that no initial estimate or prior information about the distribution is needed. However, if there happens to be a priori knowledge that the distribution is unimodal or that it is bimodal, constraining the distribution accordingly can further improve the stability and accuracy.
Properties of blends of poly(ethylene oxide) samples with different molecular weight: Kinetics of crystallization from melt
Authors: Cimmino Sossio , Greco Roberto , Martuscelli Ezio , Silvestre Clara
Published: April 2003

The crystallization kinetics of binary blends of samples of poly(ethylene oxide) with different molecular weights, namely 2000, 20 000, and 197000 has been investigated by means of polarized light microscopy in order to establish the dependence of the kinetic parameters upon the composition. The temperature and composition dependence of the growth rates of spherulites in thin films of supercooled melt has been analyzed by means of the theoretical expressions given by Hoffman and Lauritzen. The experimental results indicate that some kinetic and thermodynamic quantities such as the rate of crystallization, the equilibrium melting temperature, the free energy of formation of a nucleus of critical size, and the surface free energy of folding are strongly dependent upon the composition of the blends.
Melting behavior of syndiotacticity‐rich poly(vinyl alcohol)‐water gel
Authors: Matsuzawa Shuji , Yamaura Kazuo , Maeda Ryuzo , Ogasawara Kenji
Published: April 2003

The melting temperatures of a syndiotacticity‐rich poly(vinyl alcohol)‐water gel were measured for concentrations below 70g.dm‐3. In the gel chilled at a temperature below about 15°C the melting point first decreased monotonously then sharply in a jump and again monotonously with decreasing concentration, whereas in the gel chilled above 20°C the melting point decreased monotonously through‐out. The change of the shear modulus of a gel chilled at 0°C with the rise of temperature from 0°C to the melting point was also measured. Initially the shear modulus decreased, then increased to a maximum value, and at last decreased towards the melting temperature, whereas a gel chilled at 40°C kept an almost constant value during heating from 40°C up to a high temperature and then decreased with further rise of temperature. The turbidity of dilute solutions chilled at 0°C passed a minimum and maximum with the rise of temperature in accord with the minimum and maximum of the shear modulus. It is thus concluded that in the gel chilled at temperatures below 15°C the junctions grow to some extent with the rise of temperature.
Oxidation of tertiary amines with N‐chloronylon 66
Authors: Sato Tsuneyuki , Schulz Rolf C.
Published: April 2003

Oxidation of tertiary amines with N‐chloronylon 66 (NCN) was investigated in several organic solvents. NCN was found to oxidize N,N‐dimethylaniline (DMA) at room temperature to give N‐methylaniline with 15–50% yield, depending on the solvents used. Oxidation of N,N‐dimethylbenzylamine (DMBA) gave benzaldehyde with 15–30% yield and a small amount of N‐methylbenzylamine. A mechanism was discussed. For comparison, N‐chlorosuccinimide, a low molecular N‐chloro‐compound, was also used for oxidation of DMA and DMBA.
Gpc study of thermo‐oxidative degradation of poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Hudec Pavel , Sláma Zdeněk , Štěpánková Helena
Published: April 2003

The method of gel permeation chromatography was used to study the structural changes of poly(2,6‐dimethyl‐1,4‐phenylene oxide) in the course of thermooxidative degradation. During the degradation two principal processes occur: random scission and crosslinking. The latter process leads to the formation of insoluble fractions. The reaction rates and activation energies of both processes have been determined. The mechanism of degradation as well as the influence of some additives is discussed on the basis of experimental data.
Pharmakologisch‐aktive polymere, 18. Körperverteilung und ausscheidungsverhalten von monomerem und polymerem sulfadiazinacrylamid
Authors: Hofmann Volker , Ringsdorf Helmut , Schaumlöffel Erich
Published: April 2003

Sulfadiazinacrylamid was absorbed after oral and intraperitoneal application in rats to a high extent; the absorption from the intraperitoneum was retarded. Glucose treatment delayed the absorption after both application forms. At comparatively high renal and enteral excretion rates the biological half life time of the monomer was estimated to 8 h. A tumouraffinity was not found but there were indications for a preferred storage in the RES.

Poly[sulfadiazinacrylamide] was absorbed after intraperitoneal injection to a clear extent, where at the beginning of the treatment under simultaneous glucose load the absorption was delayed. 24 h after injection higher concentrations in metabolic organs and those of the RES were established. After oral application of the polymer an effective resorption was excluded. The elimination of the intraperitoneally injected polymer happened at negligibly low dose rates; after oral application the elimination process was finished within 24 h after treatment of the test animals. The polymer showed no tumouraffinity.
Azoinitiatoren, 9.Synthese und pfropfung azogruppenhaltiger polycarbonate
Authors: Kerber Robert , Gerum Johannes , Nuyken Oskar
Published: April 2003

Polycarbonate 3 was synthesized by copolymerisation of 4‐(p‐hydroxyphenylisopropyl)phenol with [3,5‐Bis(hydroxymethyl)phenylazo]‐methylmalonodinitrile (2a). This azo groups containing polycarbonate was employed as initiator for graft copolymerisations. The content of azo functions in the resulting copolymers was determined by 1H NMR, microanalysis, and DSC‐measurements, and Mn by vapor pressure osmometry. Grafting was carried out with styrene in 1,4‐dioxane and the resulting products were characterized by IR, 1H NMR, HPLC, and vapor pressure osmometry.
Haloaldehyde polymers, 12. Preparation and polymerization of bromodifluoroacetaldehyde
Authors: Campbell R. W. , Vogl O.
Published: April 2003

Bromodifluoroacetaldehyde (5) was prepared from methyl bromodifluoroacetate (4) by reduction with lithium aluminium hydride. 4 was in turn prepared by bromination of chlorotrifluoroethylene (1) and treatment of the resulting 1,2‐dibromo‐1‐chlorotrifluoroethane (2) with fuming H2SO4 and HgO. 5, properly purified, could be polymerized with anionic and cationic initiators to poly[oxy‐2‐(bromodifluoro)ethylidene] (12). Certain initiators produce partially or entirely amorphous soluble 12 of relatively low molecular weight. Most polymers, however, are insoluble, crystalline, and presumably isotactic. Thermal vacuum degradation of the polymers 12 gave monomer 5 in essentially quantitative yield. The thermal stability of polymers can significantly be improved by endcapping or treating with agents which replace unstable end groups. The ceiling temperature of the polymerization of 5 was determined to be +48°C. 5 was copolymerized with trichloroacetaldehyde with cationic or anionic initiators to copolymers containing predominantly units of 5. 5 could also be copolymerized with phenyl isocyanate to a polymer containing oxycarbamido linkages.
Self‐diffusion of benzene in the presence of macromolecules
Authors: Reimschüssel Władysław , Hawlicka Ewa
Published: April 2003

To measure the self‐diffusion coefficients the open‐end capillary method was used. The solvent self‐diffusion coefficients in benzene solutions of polystyrene and poly(methyl methacrylate) were determined in a concentration range up to 30g·dm−3 and in dependence of temperature. It was observed that in very dilute polymer solutions (for polymer concentration smaller than 4g·dm−3) the benzene self‐diffusion coefficients were higher than the one of pure benzene. The hypothesis is given that this effect is due to the change of benzene structure in the presence of macromolecules.
Synthesis and study of poly(8‐hydroxyquinoline‐7,5‐diylethylene)
Authors: Patel B. S. , Choxi G. S. , Patel S. R.
Published: April 2003

Poly(8‐hydroxyquinoline‐7,5‐diylethylene) (3) was prepared both by Friedel‐Craft's condensation of 8‐hydroxyquinoline (1) with 1,2‐dichloroethane (2) in the presence of anhydrous aluminium chloride and by condensation of 1 with ethylene glycol in the presence of an acid catalyst. The polymer samples were found to be insoluble in acetic acid, sulfuric acid, conc. hydrochloric acid, or formic acid. They were characterized by IR and UV spectra. Their molecular weights were determined by conductometric titration in pyridine. Viscometric studies were carried out in formic acid and in glacial acetic acid at 35°C. Solutions of the polymer samples in formic acid showed normal behaviour, whereas those in glacial acetic acid showed an abnormal behaviour. Various empirical relations were applied to correlate the viscosity data of solutions in glacial acetic acid with the appropriate concentration function. Aqueous acetic acid and simple electrolytes were used as solvents to supress the abnormal behaviour.
Polarographische Untersuchungen an monomeren und polymeren N‐Chlorcarbonamiden
Authors: Günster Engelbert , Schulz Rolf C.
Published: April 2003

The polarographic reduction of low molecular and high molecular N‐chlorocarboxamides at the dropping mercury electrode proceeds in two one‐electron‐transfer steps, which are highly irreversible. In the case of the low molecular models 1 and 2 the reaction is diffusion‐controlled, whereas in the case of the poly(N‐chloroamide) 3 the reaction is adsorption‐controlled. Reduction of several poly(N‐chloroamide)s shows always two reduction waves with a distance of 0,5 V. There is, however, no relation between the polyamide‐type and the position of the half‐wave potentials. The polarographic reduction can be used as an analytical method for quantitative determination of N‐chlorocarboxamide groups in polymers.
Über die Kinetik der Reaktion von Hexamethylendiisocyanat mit 2‐ethyl‐1,3‐hexandiol in verschiedenen Lösungsmitteln
Authors: Hager Wilhelm , Ueberreiter Kurt
Published: April 2003

The kinetics of the polyaddition reaction of hexamethylenediisocyanate with 2‐ethyl‐1,3‐hexanediol were investigated in various aprotic solvents with zero dipole moment. The reactions were followed by means of IR‐spectroscopy. The reaction is of 2nd order. Rate constants depend on the dielectric constants of solvents. Energy of activation does not depend on the nature of the solvent, its value for the first isocyanate group is 28,97 kJ/mol and 17,79 kJ/mol for the second one. It is surprising that the consecutive reaction of the second isocyanate group is faster than that of the first one, if the diol is 2‐ethyl‐1,3‐hexanediol. This has not been found before. It could be shown that in the addition reaction of the same isocyanate with 2‐methyl‐2,4‐pentanediol the reactivity of the second isocyanate group is much smaller than that of the first one, as has been found with other dioles investigated until now.
Ring opening in the polymerization of propylene oxide by the initiator systems aluminium isopropoxide or aluminium isopropoxide/zinc chloride (1:1) and the microstructure of the resulting polymers
Authors: Jedlinski Zbigniew , Dworak Andrzej , Bero Maciej
Published: April 2003

2‐Methyloxirane (propylene oxide) was polymerized by aluminium isopropoxide [Al(OiPr)3] and by the initiator system Al(OiPr)3/zinc chloride (1:1). The microstructure of the resulting polymers was investigated by 13C NMR spectroscopy. The polymer obtained with Al(OiPr)3 alone was found to contain head‐to‐tail and head‐to‐head linkages in the chain, indicating an oxirane ring opening in both α‐ and β‐positions. The polymerization by the aluminium isopropoxide/zinc chloride initiator system led to the formation of a crystalline, highly isotactic fraction and to an amorphous, almost atactic fraction of the polymer with head‐to‐tail linkages only.
Metachromasia of pinacyanol chloride induced by synthetic polyanions
Authors: Pal M. K. , Ghosh Bijan Kumar
Published: April 2003

The metachromasia of the cyanine dye pinacyanol chloride sharply depends on the nature of the polyanions the dye interacts with. The metachromatic spectra of the dye induced by polymethacrylate (only at polymer/dye mole ratios P/D>3), polyacrylate and poly(vinyl sulfate) are broad and multiple‐banded; whereas the spectra are sharp and single‐banded with poly(methacrylic acid) and polystyrenesulfonate as the chromotropes. Poly(methacrylic acid) and polystyrenesulfonate form compounds with the dye with 2:1 stoichiometry, whereas the polyanion‐dye complexes with polyacrylate and poly(vinyl sulfate) as polyanions have 1:1 stoichiometry. This observed difference in the metachromasia of this dye has been discussed in terms of the differences in stoichiometry, flexibility and conformation of the polyanion chains.
On the copolymerization of acrylonitrile with styrene in the presence of Lewis acid, 3. Photoinitiated copolymerization
Authors: Bartoň Jaroslav , Werner Peter , Capek Ignác
Published: April 2003

The rate of the acrylonitrile (AN)‐styrene (St) copolymerization (Rp) photoinitiated (λ=365 nm) by the StANZnCl2 complex at 30°C is proportional to the square root of the intensity of radiation. The limiting viscosity number [η] of alternating copolymers increases with the intensity of radiation. The 1/[η] vs. Rp relationship for the StAN copolymers is similar as has been found for the initiation of copolymerization by thermal decomposition of 2,2‐azoisobutyronitrile. Provided benzophenone combined with 2‐propanol is used as a photosensitizer, the rate of the StAN copolymerization in acetone—at constant concentrations of both comonomers, zinc chloride, and benzophenone—decreases with 2‐propanol concentration in the reaction mixture. If benzophenone alone (e.g. without 2‐propanol) is used as a photosensitizer under equal conditions, the observed values of the rate of copolymerization are lower in comparison with the system where the ternary molecular complex is empolyed as a photosensitizer. Moreover, Rp decreases with increasing concentration of benzophenone in the system. These findings are interpreted as a result of the termination reactions of ketyl radicals (hydroxydiphenylmethyl radicals) with macroradicals of copolymer.
13C NMR‐Spektroskopische Untersuchungen über den Einfluß anorganischer Salze auf die Solvatation von N,N′‐Dibenzoyl‐m‐phenylendiamin in N,N‐Dimethylacetamid
Authors: von Goldammer Eberhard , Schollmeyer Eckhard , Hirt Peter , Aichele Wilfried , Herlinger Heinz
Published: April 2003

Changes of the solvation sphere of N,N′‐dibenzoyl‐m‐phenlyenediamine (as a model substance for aromatic polyamides) in N,N′‐dimethylacetamide caused by electrolytes such as LiCl, LiBr or BeCl2 were studied by 13C NMR chemical shift measurements. The observed variations of the chemical shift data were interpreted by a stronger interaction of the solvent molecules with the carbonamide group. The relation of the carbonyl and the amide group interaction with the solvent or the solvated cations depends on the kind of electrolyte. It is not possible to correlate the obtained results with the influence of these electrolytes upon the molecular weight of the aromatic polyamides prepared in N,N′‐dimethylacetamide. Therefore some possible explanations are discussed.
Properties of solution grown crystals of aliphatic polyesters with variable amount of double bonds along the chain
Authors: Crispino Luigi , Maglio Giovanni , Martuscelli Ezio , Palumbo Rosario , Pracella Mariano
Published: April 2003

In order to elucidate the relations between morphological habits, thermal behaviour and chemical structure of polymers, aliphatic polyesters with variable amount of trans‐double bonds along the backbone chain were crystallized from dilute solutions in 1‐propanol and 1‐butanol. The crystals were studied with electron microscopy, differential scanning calorimetry, and wide angle X‐ray diffraction. The morphology of solution grown single crystals and some thermodynamic quantities such as the equilibrium dissolution and melting temperature and the enthalpy and entropy of fusion are influenced by the percentage of unsaturated comonomer. The thermal behaviour and the X‐ray diffraction of these crystals suggest that saturated and unsaturated repeating units are able to cocrystallize.
Application of spin trapping technique to radical polymerization, 16. Photo‐decomposition of diphenyl disulfide and initiation mechanism: Evaluation of relative reactivities of vinyl monomers toward phenylthio radical
Authors: Sato Tsuneyuki , Abe Masao , Otsu Takayuki
Published: April 2003

To clarify the initiation process in radical polymerizations with diphenyl disulfide (DPDS) as initiator, spin trapping technique was applied to the reaction of vinyl monomers with the phenylthio radical (1), which was produced by photolysis of DPDS. 2‐Methyl‐2‐nitrosopropane (BNO) was used as a spin trapping agent. When DPDS was photo‐decomposed in benzene in the presence of BNO radical 1 was trapped as the corresponding aminyl oxide radical 2, which is unstable at room temperature. The photolysis of DPDS in vinyl monomers of type H2CCXY, however, gave only aminyl oxide radicals resulting from their propagating radicals C6H5SCH2C˙XY. Contrary to the results obtained with tert‐butoxyl radicals, radical 1 was found to undergo exclusively addition reaction to the double bond of the α‐methyl‐substituted monomers, such as methyl methacrylate or methacrylonitrile, with no hydrogen‐abstraction reaction from their α‐methyl group. Relative rates of the initiation reactions of vinyl monomers with radical 1 were also determined by spin trapping technique. It was found that the reactivities of vinyl monomers toward radical 1 are controlled by both polar and resonance effects.
Dilute solution properties of methyl methacrylate/acrylonitrile random copolymers, 1. Mark‐Houwink relation
Authors: Kashyap A. K. , Kalpagam V.
Published: April 2003

Studies on the dilute solution properties of methyl methacrylate/acrylonitrile random copolymers of 0,566 mole fraction (m. f.) of acrylonitrile (AN), designated as MA3 and of 0,657 m. f. of AN, designated as MA4 reveal that the Mark‐Houwink exponent values a for MA3 lie in the range 0,6 to 0,8 and for MA4 in the range 0,8 to 1,1 in the solvents studied, viz. acetonitrile (MeCN), 2‐butanone (MEK), N,N‐dimethylformamide (DMF) and γ‐butyrolactone (γ‐BL) at the temperatures 30°C, 45°C and 60°C. Such large values of a suggest that these copolymer chains are highly extended in these solvents. The decrease of [η] with an increase in temperature also supports the above conclusion that these are very good solvents.
Gelchromatographische refraktionierung, 1. Ein verfahren zur korrektur von gelchromatogrammen
Authors: Berger K. C.
Published: April 2003

A mathematical method is proposed for calculating the gel chromatogram w(v0) after correction with the instrument spreading function D(v, v0) and for calculating D(v,v0) using experimental data on the basis, that a gel chromatographic polymer fraction of the chromatogram e(v) is collected and injected again. The chromatogram of this fraction c(v) can be described by the integral equation:

where v0 is the elution volume and v1 is the volume at which the fraction is collected. The solution of this equation simultaneously with Tung's equation by way of minimizing is suggested.
Über Polyarylenalkenylene und Polyheteroarylenalkenylene, 10. Synthesen und Charakterisierung von Poly‐(3,5‐dimethylthiazolo [4,5‐f]benzthiazoldiium‐2,6‐diylvinylenarylenvinylen)en und einigen Modellverbindungen
Authors: Koßmehl Gerhard , Bocionek Peter , Manecke Georg
Published: April 2003

From 2,3,5,6‐tetramethylthiazolo [4,5‐f]benzothiazoldiium diperchlorate (2) and dialdehydes of the benzene and the thiophene series the corresponding poly(3,5‐dimethylthiazolo[4,5‐f]benzothiazoldiium‐2,6‐diylvinylenarylenevinylene diperchlorate)s 6a–c were synthesized via Knoevenagel condensation. Analogous reactions with comparable monoaldehydes gave a series of model compounds 4a–c. The structures were confirmed by elemental analyses and by IR and electronic spectra. In addition, the model compounds were characterized by their 1H NMR and mass spectra. The electrical dark conductivities of all substances and the thermooxidative degradation of the polymers were studied.
Kalorimetrische Untersuchungen zum Lösungsverhalten von Polyacrylsäure und Poly(natriumacrylat) in Wasser, Formamid und Ethylenglykol
Authors: Klein Joachim , Scholz Wilfried
Published: April 2003

Heats of solution and heats of dilution of poly(acrylic acid) (PAAcH), poly(sodium acrylate) (PAAcNa), and poly(acrylamide‐co‐sodium acrylate) (1:1) (PAAm/PAAcNa) in water, formamide (FA), and ethylene glycol (EG) as measured at 25°C, are reported. While for PAAcH/H2O and PAAcH/EG only minor caloric effects are observed, the heats of solution for PAAcNa/H2O are strongly exothermic as a result of dissociation of the polysalt. Heats of dilution in this system are endothermic because of the hydrolysis reaction. PAAcH/FA shows large negative enthalpies on dissolution as well as on dilution. This is due to the dissoziation of the COOH‐groups which is much more pronounced in FA than in the aqueous system because formamide has a greater ionizing capability. Comparison between the behaviour of copolymer PAAm/PAAcNa and physical admixing of the homopolymers confirms the specific neighbouring group interaction of carboxylate and carbonamide groups along the same chain. Comparing the calorimetric results for PAAcH with those for the low‐molecular‐weight model compound propionic acid, it becomes evident that the differences are mostly due to the different state of order of the pure compounds, namely, due to the chain structure, the COOH‐groups in the polymers are not as flexible as in the monomers. Therefore, in the pure polymer less hydrogen bonds are formed than in the pure propionic acid. The calorimetric results are discussed in the light of previous work on viscosimetric dilute solution behaviour of these systems, showing the consistency of the different experimental findings.
Association of block copolymers in selective solvents, 1. Measurements on hydrogenated poly(styrene‐isoprene) in decane and in trans‐decalin
Authors: Mandema W. , Zeldenrust H. , Emeis C. A.
Published: April 2003

The dilute solution properties and association of hydrogenated poly(styrene‐isoprene) two‐block copolymers in decane and trans‐decalin have been studied by means of viscosity, diffusion and light‐scattering measurements. Data were obtained for two samples with molecular weights of 48 000 and 80 000, and both with a styrene content of 38%. In trans‐decalin the normal behaviour of a non‐associating polymer is found. Association occurs in decane with the formation of compact micelles, composed (at ambient temperatures) of about 80 molecules. In contrast to what is observed in other associating two‐block systems, the transition to the completely dissociated state at elevated temperatures causes a drop of the intrinsic viscosity. Moreover, and this is not evident from the viscometric results, the diffusion and light scattering studies reveal that in the intermediate region between association and dissociation another kind of structure with very large dimensions is formed that exists over an extended temperature range. A qualitative description of the observed phenomena is given.
Block copolymers of fluoral oligomer with urethanes: Preparation and thermal properties
Authors: Busfield W. Ken , Cowie Ian M. G. , Mondal M. A. Sattar
Published: April 2003

Two series of block copolymers have been synthesized comprising of soft polytrifluoroacetaldehyde (polyacetal) segments and of hard 4,4′‐methylenedi(phenyl isocyanate)/cis‐cyclohexane‐1,4‐diol polyurethane segments. The series‐A copolymers in which the soft segments were directly bound to the hard segments had significantly lower thermal stability than the series‐B copolymers in which the soft segments were linked to the hard segments by sebacic ester units. In both series the thermal stability decreased with increasing soft segment content. The series‐A copolymers exhibited two thermal transitions both characteristic of Tg's and separated by about 60 K. In contrast the series‐B copolymers exhibited two characteristic Tg's separated by 200–250 K, depending on composition, together with an additional endothermic transition at about ambient temperature. All transitions for both series decreased with increasing soft segment content. The observations have been compared with those of other polyether and polyester based polyurethanes.
Investigation of the topochemical solid‐state polymerization of a diacetylene by X‐ray methods and brillouin‐spectroscopy
Authors: Enkelmann V. , Leyrer R. J. , Wegner G.
Published: April 2003

The topochemical polymerization of the substituted diacetylene, 2,4‐hexadiynylene bis(p‐toluenesulfonate) (1), has been followed by X‐ray crystallography and by determination of the elastic constants of polymerizing crystals. For the first time the crystal structure of a polymerizable diacetylene monomer has been solved and the coordinates of all atoms prior and after the reaction have been determined. The length of the growing polymer chains and their distribution in the monomer matrix can be determined by the evaluation of the Brillouin spectra in terms of a model which considers the polymerizing crystal as a composite material of high‐modulus rod‐like macromolecules dispersed in the low‐modulus matrix of the residual monomer.
Zur stabilität der komplexen anionen bei der kationischen polymerisation
Authors: Heublein Günther , Spange Stefan , Hallpap Peter
Published: April 2003

The counterions appearing in the mechanism of the cationic polymerization are able to decay according to
magnified image
and so give rise to termination reactions. For the model systems (C6H5)3C⊕MtX⊖n+1(Mt = B, Al, Sn, P, As, Sb, In, Ti, Fe; X = F, Cl, Br) the decay has been investigated by spectroscopic and conductometric methods. The overall decay rate constant kz is hardly influenced by traces of water (cH2O<10−3mol.l−1) and by structure variations of the cation. On the other hand, kz increases by decreasing the concentration of the salt. When the structure is varied kz increases with decreasing donor strength of the ligands X; the sensitivity of the anion to changes in the ligand sphere increases corresponding to the ionization potential of the central atom Mt. Addition of tetracyanoethylene raises the stability of the anions.

The results can be explained by the HSAB principle and fit well in a scheme of stabilization of anions by acceptors.
Mechanical denaturation of high polymers in solutions, 34. Nucleation and growth of poly(vinyl alcohol) crystals from flowing solution
Authors: Matsuzawa Shuji , Yamaura Kazuo , Umeda Yōichi , Inoue Yūji , Kitamura Hisako , Pak Sang‐Yong
Published: April 2003

The nucleation and growth of the crystals of poly(vinyl alcohol) (PVA) from its solution keeping in contact with air under steady‐state flow were investigated. The nucleation was considered to occur close to the solution surface because of the adsorption of PVA molecules to the solution surface. It was ascertained by the following results. The initial fibrillar crystal appeared under the solution surface after a few seconds of stirring. From the measurement of the surface tension of PVA solutions, PVA molecules were recognized to be adsorbed to the solution surface in a very short time. The random coil of PVA molecule cannot be extended and oriented in a solution stirred under steady‐state flow with a shear rate below 5.103 s−1 applied in this experiment. This was concluded from an evaluation of the chain extension in a velocity gradient in shearing flow using the dumbbell model. The propagation of the precipitate is accelerated by turbulent flow induced by the flow of the solution itself, foams and precipitates.
Coordination polymers of 1,2,5,8‐tetrahydroxyanthraquinone
Authors: Banerjie Vishwanath , Dey Arun K.
Published: April 2003

From analytical studies, infrared and reflectance spectra, magnetic and thermogravimetric measurements of Cu(II), Ni(II), Co(II), Mn(II), Fe(II), and UO2(VI) complexes of 1,2,5,8‐tetrahydroxyanthraquinone, it was concluded that the complexes are polymeric coordination complexes with octahedral geometry. These were synthesized by refluxing an equimolar mixture of the ligand and hydrated metal acetates in N,N‐dimethylformamide at 140°C. Elemental analyses indicated a ligand: metal ratio of 1 : 1 and the association of water molecules with the central metal. The decreasing order of thermal stability of the complexes is: Mn(360°C)>Fe(340°C) ≈︁ Co(340°C)>Ni(320°C)>Cu(300°C).