bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the polymerization of the N‐carboxyanhydride of γ‐benzyl L‐glutamate, initiated by low‐molecular‐weight and polymeric initiators
Authors: Ovsiannikova Lujdmila A. , Rudkovskaya Galina D. , Vlasov Gennadii P.
Published: April 2003

N‐carboxyanhydride of γ‐benzyl L‐glutamate (N‐CA‐γ‐BG) was polymerized with the lowmolecular‐weight initiators 2,2′‐dithiodiglycinanilide (1) and 2,2′‐azo‐2,2′‐dimethyldipropionohydrazide (2) and with poly(methyl methacrylate) (PMMA) of different molecular weights containing amino and hydrazide end groups, exhibiting different nucleophilicities. For comparison, the N‐CA was also polymerized with initiators described in the literature. It could be shown that the induction period depends on the nucleophilicity of the end groups of the initiator. In contrast to the low‐molecular‐weight initiators, the polymerization of the N‐CA with PMMA proceeds without acceleration.
Microstructure of styrene‐methacrylic acid and styrene‐acrylic acid copolymers, 1. 1H NMR study of methylated styrene‐methacrylic acid copolymers
Authors: S̀witała Maria , Wojtczak Zbigniew
Published: April 2003

Copolymers of styrene and methacrylic acid were obtained in emulsion, benzene solution, and by grafting. 1H NMR measurements were carried out on the methoxy proton region of their methylated derivatives. From these measurements mole fractions of methacrylic acid centered triads, run numbers, number‐average sequence lengths of methacrylic acid and styrene, and the probability of finding a sequence of n methacrylic acid units were determined. All these quantities are very similar for the emulsion and random copolymers of similar composition. Emulsion styrene‐methacrylic acid copolymers can therefore not be regarded as block copolymers.
Microstructure of styrene‐methacrylic acid and styrene‐acrylic acid copolymers, 2. 1H NMR study of methylated styrene‐acrylic acid copolymers
Authors: S̀witała Maria , Wojtczak Zbigniew
Published: April 2003

The microstructure of styrene‐acrylic acid copolymers prepared in emulsion was studied and compared with the structure of copolymers prepared in benzene solution and by grafting. An analysis of the 1H NMR spectra in the methoxy proton region of methylated copolymers was carried out and mole fractions of acrylic acid centered triads, run numbers, number‐average sequence lengths of acrylic acid and styrene, and the probability of finding a sequence of n acrylic acid units were determined. From these data it is found that the difference in microstructure of emulsion and random copolymers is not great if the copolymers contain up to 30 mol‐% of acrylic acid units, but increases with increase in the acid content of copolymers.
Dielectric relaxation of poly(tolyl methacrylate)s
Authors: Kihira Yasuharu , Sugiyama Kazuo
Published: April 2003

The dielectric relaxation of poly(phenyl methacrylate) and of poly(o‐, m‐, andp‐tolyl methacrylate)s was studied over a wide frequency and temperature range. These samples show three relaxation processes termed α, β, and γ within the temperature ranges 130 to 160°C, 50 to 120°C, and −60 to −20°C, respectively. The α‐ and β‐processes are attributed to the micro‐Brownian motion of the main chain and of the entire side chain, respectively. The γ‐process is suggested to be associated with the relaxation of the tolyl group at the end of the side chain.
Molecular and crystal structure of bis(4‐mercaptophenyl) sulfide as a model compound for poly(1,4‐phenylene sulfide)
Authors: Garbarczyk Józef
Published: April 2003

The molecular and crystal structure of bis(4‐mercaptophenyl) sulfide (3) was determined by means of an X‐ray diffraction analysis. The crystals are monoclinic, P21 /n with four molecules in the unit cell of the dimensions: a = 5,752 (1), b = 25,767 (9), c = 7,954 (2) Å and β = 95,2 (1)°. The structure was solved by direct methods and refined by least‐squares techniques up to R = 0,075 for 1 280 independent reflections. The molecules of 3 do not have own symmetry and are arranged in the unit cell in chains along the 21 axes. Between sulfur atoms of neighbouring molecules hydrogen bonds are formed. From investigations of 3 and poly(1,4‐phenylene sulfide) (2) at low temperatures (down to 90 K) similarities of changes in the crystal structures of both substances were evidenced.
Polymeric bound porphyrines and their precursors, 3. Photoredox properties of combined moieties of porphyrine and phthalocyanine, covalently bound to polystyrene
Authors: Wöhrle Dieter , Krawczyk Gerhard
Published: April 2003

Copolymers containing covalently bound phthalocyanine moieties (4) or tetraphenylporphyrine moieties (5) were prepared by the reaction of partially chloromethylated polystyrene (3) with the low molecular substituted phthalocyanine 1b and tetraphenylporphyrine 2b, respectively. Combined binding of moieties of 1b and 2b yielded polymer 6. The photoredox behavior of 1, 2, 4, 5 and 6 was investigated under irradiation with visible light in the presence of a donor and an acceptor. Mixtures of sensitizers (1 + 2 and 4 + 5) resulted in reduced photocatalytic properties. Only in the case of 6, due to reduced intermolecular interactions, higher yields of photochemical reaction products were obtained.
N‐carboxyanhydride of 4‐amino‐4‐carboxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl, a new paramagnetic monomer
Authors: Seidemann Rolf , Dulog Lothar
Published: April 2003

N‐carboxyanhydride of 4‐amino‐4‐carboxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (5), a new paramagnetic monomer, was synthesized, starting from 2,2,6,6‐tetramethyl‐4‐oxo‐piperidine (1), which was oxidized to 2,2,6,6‐tetramethyl‐4‐oxo‐piperidine‐1‐oxyl (2). Applying the Bucherer‐Bergs synthesis, 4‐amino‐4‐carboxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (4) was obtained. The key step in the synthesis of 5 is the reaction of the derived amino acids 4a and 4c with phosgene. From the two procedures which were considered the reaction of 4c with phosgene affords the N‐carboxyanhydride 5 in good yield. 5 is suited for spin labeling.
High molecular weight chitosan 6‐O‐sulfate. Synthesis, ESR and NMR characterization
Authors: Focher Bonaventura , Massoli Alberto , Torri Giangiacomo , Gervasini Antonella , Morazzoni Franca
Published: April 2003

Selective sulfation of the primary hydroxyl group of chitosan was performed by means of the pyridine‐SO3 complex after the positions 2 and 3 of the aminoglucopyranosidic ring were protected by coordination with copper ions. The requirements for complexing copper ions were investigated as a function of the pH and Cu(II)/chitosan mole ratio of the starting solution. Cu(II)‐chitosan complexes were characterized by ESR and 13C NMR CP‐MAS investigations; two different paramagnetic Cu(II) species were observed, whose relative quantity changes by changing the pH of the starting solution. The g tensor values (species I: g1‖ = 2,28, g1‖ = 2,06, A2‖ = 160 G; species II; g2‖ = 2,24, g2‖ = 2,06, A2‖ = 160 G) are consistent with a CuN2O2 chromophore. The sulfation reaction was studied in the range of 25 to 75°C using 2 : 1 to 6 : 1 pyridine‐SO3/Cu(II)‐chitosan mole ratios. Under optimized reaction conditions, a selective 6‐O sulfation was obtained in more than 90% yield.
The characteristic ratio of poly(methacrylic acid) in organic solvents
Authors: Horský Jiří , Petrus Vladimír , Bohdanecký Miloslav
Published: April 2003

Parameters of the Mark‐Houwink equation for poly(methacrylic acid) (PMAA) in methanol at 25°C, [η] = 0,0224 · M0,679, were determined and found to differ markedly from those reported earlier for 26°C. The value of the exponent along with the high value of the second virial coefficient confirms that near to 25°C methanol is not a theta‐solvent for PMAA. By employing extrapolation according to Tanaka, the characteristic ratios C of PMAA in methanol (C = 12,0) and in 2‐ethoxyethanol (C = 9,7) were determined from viscosity data at 25°C. The unperturbed dimensions of PMAA depend on the solvent used. They are larger in organic solvents than in water, but the difference is not so high as assumed before. By using the Stockmayer‐Fixman extrapolation, the characteristic ratio for PMAA in 2‐ethoxyethanol was determined at 70°C, i.e. at a temperature not too far from theta‐conditions (Θ = 65°C, C = 8,2). A comparison with the value for 25°C shows that the unperturbed dimensions of PMAA decrease with increasing temperature.
Influence of termination and transfer on molecular weight distribution of polymers, 6. Chain transfer to monomer and spontaneous termination
Authors: Yuan Cui‐ming , Yan De‐yue
Published: April 2003

In the previous parts of this series, a mathematical procedure was developed for the derivation of molecular size distribution functions of polymers generated in several ionic polymerizations. This paper follows this mathematical procedure to treat theoretically the kinetics of cationic and anionic polymerizations with instantaneous initiation, chain transfer to monomer, and spontaneous termination. The expressions of molecular size distribution functions and other molecular parameters are derived rigorously. Moreover, the simultaneous influence of chain transfer to monomer and spontaneous termination on molecular size distribution is illustrated by means of several numerical examples.
On the preferential extraction of the more isotactic parts of PVC with acetone. A verification by 13C NMR analysis
Authors: Martínez Gerardo , Mijangos Carmen , Millán José Luis , Alemany Antonio
Published: April 2003

Acetone‐soluble and ‐insoluble fractions were obtained from two different PVC samples: a polymer prepared in our laboratory at 60°C using 2,2′‐azoisobutyronitrile (AIBN) as initiator (sample A) and a commercial polymer prepared at 70°C (sample B). The content of isotactic, syndiotactic and heterotactic traids was accurately measured by high resolution 13C NMR. From the obtained data it follows that the isotactic triads accumulate preferably in the soluble fraction, the amount of which depends on the type of polymer. In agreement with earlier results, the soluble fraction is about 40% less stable than the insoluble fraction. The reasons for this behaviour are discussed in the light of the higher content of both isotactic triads and some defect structures, as found in the low molecular weight soluble extracts of PVC.
Photoreaktionen von Biscyclopentadienyltitandichlorid in einer monomerhaltigen polymethylmethacrylat‐matrix
Authors: Kopietz Michael , Lechner M. Dieter , Steinmeier Dietrich G. , Franke Hilmar
Published: April 2003

It could be demonstrated that methyl methacrylate (MMA) in a poly(methyl methacrylate) (PMMA)‐matrix can be polymerized by photoinduction with titaniumbiscyclopentadienyl dichloride (titanocene chloride). The photoinduced polymerized portion of MMA consists practically only of isotactic PMMA. The differences in polymerization by irradiation with laser light and with monochromatic light of a mercury light source with the same wavelength are discussed.
Copolymerization of 2‐chloro‐N,N‐dimethylacrylamide
Authors: Smets Georges , Samyn Celeste , Swaelen Kathleen
Published: April 2003

2‐Chloro‐N,N‐dimethylacrylamide (CNA) does not homopolymerize easily (2% after 12 days) in contrast to 2‐chloroacrylic esters. Its copolymerization with styrene (St) and methyl methacrylate (MMA) is governed by the following copolymerization parameters: rCNA = 0,03 and rMMA = 3,4; rCNA = 0,2 ± 0,05 and rSt = 1,5 ± 0,2. The very low rates of copolymerization and the low molecular weights of the copolymers are interpreted on the basis of the formation of sterically hindered resonance stabilized radicals, and of high chain transfer constants.
Comparisons among some tetraalkoxysilanes in the hydrolytic precipitation of silica into elastomeric networks
Authors: Sur G. S. , Mark J. E.
Published: April 2003

Four tetraalkoxysilanes Si(OR)4 were absorbed into networks of polydimethylsiloxane and then hydrolyzed, using a variety of catalysts, to give reinforcing silica particles. On the basis of the amount of silica precipitated and the extent of reinforcement, the (decreasing) order of effectiveness was found to be tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and tetramethoxysilane.
Thermodynamics of gas solubility in polymeric liquids
Authors: Panayiotou Constantinos G.
Published: April 2003

A modified fluid‐lattice model for mixtures of fluids is presented. Expressions for the basic thermodynamic quantities of mixing are given. From the equation for vapor‐liquid equilibrium, the expression for the Henry constant at low pressure is derived. Weight fraction Henry constants for gas‐polymer and gas‐polymer‐polymer systems are derived as limiting cases. Predictions of theory about the effect of temperature on the Henry constants are compared with experimental data for twenty two polymer‐organic vapor systems. In almost all cases the Henry constants are reproduced within the limit of experimental error. The effect of pressure on gas solubilities is considered. The effect of polymer‐polymer binary interaction parameter on the Henry constant in a gas‐polymer‐polymer mixture is also discussed.
Lyotropic mesophase of imogolite, 1. Effect of polydispersity on phase diagram
Authors: Kajiwara Kanji , Donkai Nobuo , Hiragi Yuzuru , Inagaki Hiroshi
Published: April 2003

The acidic aqueous solution of imogolite is proposed to be an ideal lyotropic system. No temperature dependence was marked on the two phase boundary concentrations (A and B points) of imogolite solutions as predicted by the theories of Flory and Onsager. A satisfactory quantitative agreement was observed with Onsager's theory. The polydispersity of rod lengths was found to shift the A point towards lower concentrations than expected from theory.
Synthesis and characterization of poly(dimethylsiloxane) based liquid crystals
Authors: Allen Richard C. , Wilkes Garth L. , Yilgor Iskinder , Wu Dshilian , McGrath James E.
Published: April 2003

A novel set of low molecular weight copolymers have been synthesized which were based on the attachment of mesogenic groups to the terminal points of oligomer backbones. The placement of the groups at the end of the chains apparently allowed a second phase to form more easily than if the groups were attached along the backbone as pendant groups. The nature of the coupler or spacer was determined to influence whether the end groups crystallized or formed liquid crystallinity. The observation of liquid crystallinity was found to depend primarily on the relative concentration of mesogen to backbone molecular weight. Depending upon the specific coupler, there existed two critical values of molecular weight between which mesophase behavior was observed. Below a certain value, the end groups were found to crystallize. Above another critical value, there was no measureable second phase. Liquid crystallinity was only observed when the molecular weight was intermediate between the two critical values.
Second virial coefficient revisited, 3. Viscosity of dilute polymer solutions: Molecular weight dependence of the Huggins coefficient
Authors: Gundert F. , Wolf B. A.
Published: April 2003

The variation of the Huggins coefficient KH with the relative molecular mass M of the polymers was measured for solutions of polystyrene and of polyisobutylene and found to be most pronounced in the case of thermodynamically good solvents but vanishing at the theta‐temperature, where the individual curves kH (T; M) intersect with each other. The experimental results are interpreted as a consequence of the rheological inequality of inter‐ and intra‐molecular contacts between polymer segments. A model is presented according to which kH should be a linear function of M−(a−0,5), where a is the exponent of the intrinsic viscosity‐relative molecular mass relationship (Kuhn‐Mark‐Houwink). The evaluation of the present data, together with information from the literature, yields the individual effects from inter‐ and intra‐molecular intersegmental contacts, their interdependence, and their variation with the thermodynamic quality of the solvent. In thermodynamically poor solvents, were the polymer coils are nondraining, these effects are found to differ extremely; however, they approach each other as the goodness of the solvent improves and the coils become draining; their identity can be extrapolated for a = 1.
Study on the mechanism of 1‐cyanoguanidine cure of epoxy resins using model compounds
Authors: Galy Jocelyne , Gulino Danièle , Pascault Jean‐Pierre , Pham Quang Tho
Published: April 2003

The mechanism of the reaction of 2,3‐epoxypropyl phenyl ether (2), as a model compound, with 1‐cyanoguanidine (3), for which different pathways have been proposed, is investigated using HPLC and 1H NMR spectroscopy. The effect of stoichiometric ratio, temperature and catalytic reagent was studied. It was found that, independent on the stoichiometric ratio, at low temperature, etherification and addition at the primary amino group takes place and reaction of the cyano group only to a low extend. At higher temperature, HPLC diagrams show different peaks indicating a different mechanism.
Experimental evidence for the regiospecific primary mode of styrene insertion into metal‐carbon bonds of an isospecific Ziegler‐Natta catalyst
Authors: Benaboura Ahmed , Deffieux Alain , Sigwalt Pierre
Published: April 2003

Styrene/1‐hexene copolymers of different chemical composition were prepared with a classical isospecific Ziegler‐Natta catalyst, TiCl3(H)‐AlEt3. Their structure and the distribution of the monomeric unites was analyzed by GPC double detection and 1H and 13C NMR. The chemical arrangement of isolated and blocked styrene monomeric units between sequences of hexene monomeric units was also investigated. 13C chemical shifts of carbon atoms in the copolymers and in addition in model molecules of the two modes of styrene addition indicate that styrene insertion into carbon‐metal bonds of the catalyst proceeds according to a primary mode. Mechanistic implications of these results are discussed.
Polymères porteurs de dérivés du glycérol, 7.. Synthèse d'esters d'époxy‐2,3 propyle
Authors: Soutif Jean‐Claude , Razermera Faly , Brosse Jean‐Claude
Published: April 2003

2,3‐Epoxypropyl esters were obtained in two steps from carboxylic acids or in one step from their alkali salts by reaction with 1‐chloro‐2,3‐epoxypropane or from the acid chloride with 2,3‐epoxy‐1‐propanol. The kinetic parameters of these reactions were studied with acetic acid and sodium acetate to evaluate the optimal conditions for the synthesis of these esters with the intention to apply them to polymers containing carboxylic groups.
Additive rules for the 13C NMR shifts of methyl‐substituted alkanes and ethylene‐propylene copolymers
Authors: Cheng H. N. , Bennett Mark A.
Published: April 2003

Detailed 13C NMR chemical shift rules are devised for ethylene and propylene polymers and for low‐molecular‐weight analogs. The rules are additive and account for substituent effects as well as for configurational sequences. The agreement between the observed and the predicted shifts is excellent. A computer program has been written to obtain the predicted shifts quickly and with minimum effort.
Influence of termination and transfer on molecular weight distribution of polymers, 7. Impurity transfer
Authors: Yan De‐yue , Yuan Cui‐ming
Published: April 2003

A mathematical procedure is developed to deal with the kinetics of ionic polymerization with impurity transfer and instantaneous initiation. Besides the technique of variable transformation, the integration of an implicit function is applied. The expressions of the molecular size distribution function and other molecular parameters are derived regorously, and several examples for numerical computations are given.
Water‐soluble copolymers, 16. Studies of the behavior of acrylamide/N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide copolymers in aqueous salt solutions
Authors: McCormick Charles L. , Hutchinson Brewer H. , Morgan Sarah E.
Published: April 2003

The behavior of N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide more commonly known as diacetone acrylamide (DAAM) polymers and acrylamide/diacetone acrylamide copolymers in aqueous and non‐aqueous solutions has been examined. 13C NMR and IR studies do not support the formation of a six‐membered hydrogen‐bonded ring structure in the DAAM moiety as an explanation of the unusual increase in solution viscosity shown by these copolymers upon addition of salt. A 12‐membered hydrogen‐bonded structure involving the diacetone acrylamide side chain and an adjacent acrylamide unit is proposed which is consistent with the available data and which would explain the viscosity behavior. Another possible structure involves hydrogen bonding between adjacent comonomers through amide/imine resonance structures. Copolymer microstructure as indicated by calculated pentad and triad frequencies supports either of these proposed structures.
Polymerization of acetylene with Ti(OC4H9)4/butyllithium as catalyst system and silicone oil as reaction medium
Authors: Munardi Adriantono , Theophilou Nicolas , Aznar Raymond , Sledz Joseph , Schué François , Naarmann Herbert
Published: April 2003

A polymerization reaction catalyzed by Ti(OC4H9)4/butyllithium in a reaction medium of silicone oil yields a homogeneous and highly conductive polyacetylene when doped with iron (III) chloride. The effect of the transition metal halide on polyacetylene was studied by solution doping with FeCl3/nitromethane as a function of time.
Graph theory of configurational and viscoelastic properties of polymers, 3. Cyclic and star‐shaped chains containing small copolymeric blocks
Authors: Yang Yuliang , Yu Tongyin
Published: April 2003

Graph theory of configurational and viscoelastic properties of polymers has been extended to treat cyclic and star‐shaped chains containing small copolymeric blocks in the free‐draining limit. Analytical expressions of the zero‐shear‐rate viscosity η4 and the steady‐state recoverable compliance J of these types are obtained. In the Rouse theory of viscoelastic behaviour η0 and J are directly related to the moments of the radius of gyration 〈S2〉 and 〈S4〉, hence both can be obtained simultaneously. Particularly, the relaxation spectrum of cyclic alternating block copolymer chains can also be obtained. The results obtained in this paper indicate that the structures of these types of chains are altered locally by the incorporation of a small concentration of another type of segments; the variation in viscoelasticities cannot be ignored and shows a strong dependence on block configuration. The results obtained may prove useful for understanding and interpreting the rheological data of block copolymers.
Phase‐transfer catalysis of phosphonium ions derived from poly[(P‐phenyl)trimethylenephosphine]
Authors: Kobayashi Shiro , Suzuki Masato , Sakaya Tai‐ichi , Saegusa Takeo
Published: April 2003

Polymeric phosphonium ion species having different content of phosphonium units (4a and 4b) were prepared from poly[(P‐phenyl)trimethylenephosphine] (3). Phase‐transfer catalysis of 4 was examined by means of a typical SN2 reaction (1) in a bi‐phase system. The apparent rate constant (kobs) was determined, its magnitude being smaller by about one order than that of the corresponding monomeric phosphonium ion 5. Crosslinked polymeric phosphonium ion species were coated on powdery alumina and used as a phase‐transfer catalyst for reaction (1) in a triphase system. Due to the inhomogeneous reaction, the kobs value was much smaller (1/5) than that in presence of 4.
Strictly alternating copolymers containing parabanic acid and amide or imide moieties
Authors: Bennett Cynthia , Heitz Walter
Published: April 2003

1,3‐Bis(4‐aminophenyl)imidazolidinetrione dihydrochloride (1) was synthesized and used as starting material for the synthesis of strictly alternating copolymers. Fully aromatic copolymers containing parabanic acid and amide moieties (7a, b) were found to exhibit high glass temperatures and good thermal stability. Meltable copolymers with parabanic acid and amide moieties (7d–j) could be obtained by introducing flexible aliphatic spacers. The use of an unusually short, but symmetrically branched spacer was particularly effective. The strictly alternating, thermally stable copolymer 10 was synthesized from 1 and pyromellitic dianhydride. By using the trimethylsilyl ester of polyamic acid 11, the imidization temperature could be lowered by 100°C.
Determination of kinetic parameters of ethyl methacrylate polymerization by using the dead‐end procedure
Authors: Çatalgil Huceste H. , Baysal Bahattin M.
Published: April 2003

Kinetics of polymerization of ethyl methacrylate initiated by 2,2′‐azoisobutyronitrile (AIBN) was studied applying the “dead‐end” theory. This theory is appropriate to examine the solution polymerization of this monomer in benzene at θ > 60°C. Radical polymerizations of ethyl methacrylate were carried out at 60–110°C. By using the procedures of the dead‐end theory, the rate of decomposition and the initiator efficiency of AIBN were determined. Kinetic parameters of the solution polymerization of ethyl methacrylate were calculated and the results were compared with the literature values.
Cationic ring opening polymerization of 4,5‐dihydro‐2‐[2‐(9‐anthryl)ethyl]‐1,3‐oxazole
Authors: Simionescu Christofor I. , Onofrei Geta , Grigoras Mircea
Published: April 2003

A new monomer, 4,5‐dihydro‐2‐[2‐(9‐anthryl)ethyl]‐1,3‐oxazole (5) was synthesized and polymerized by cationic ring‐opening isomerization. The polymerization was carried out in bulk or in solution, using methyl tosylate, ethylene ditosylate and α‐tosyl‐ω‐tosyloxypoly(oxyethylene) [poly(ethylene oxide)ditosylate] as initiators. The polymers were characterized by IR, 1H NMR and UV spectroscopy.
Polyacrylate graft polymers prepared by grafting of monomethoxypoly(ethylene oxide) homopolymers onto acrylic acid: Self‐gelling polymers
Authors: Gramain Philippe , Frere Yves
Published: April 2003

Polyacrylates of monomethoxypoly(ethylene oxide)

Systematic name for MePEO: α‐hydro‐ω‐methoxypoly(oxyethylene).

(MePEO) were prepared by grafting MePEO on prepolymerized acryloyl chloride polymers of different molecular weights. Copolymers with carboxyl groups were also prepared by the addition of both water and MePEO. The polymers spontaneously form irreversible gels in water as soon as the degree of polymerization exceeds a certain limit. This gel formation confirms preceding results on similar polymers obtained by polymerization of MePEO acrylate and methacrylate macromonomers. It is concluded that the gelification phenomenon is not due to chemical cross‐linking but rather to the presence of a high density of strongly interacting grafts of PEO on the polymer backbone. This new type of self‐gelling system is considered to be of special interest.
Method for the determination of the relative spherulite growth rate, 2. The shielding effect
Authors: Lednický František
Published: April 2003

The method for the evaluation of spherulite growth after completed crystallization is further refined by comparison of the predicted and real shapes of the more slowly growing spherulite encompassed by the faster‐growing one. The shielding effect (the effect of distorted growth of the faster‐growing spherulite behind the more slowly‐growing one) is theoretically described, compared with the observation, and used for the evaluation of the relative rate of spherulite growth. As an example, measurements are reported with samples of poly(vinylidene fluoride).
Der interferenzeffekt von gestreckten markoff‐ketten erster ordnung, 1. Einkettenrechnung unter vernachlässigung der atomistischen comonomerstrukturen
Authors: Bonart Richard , Mulzer Georg , Dietrich Johann
Published: April 2003

The previously derived so called Bonart‐Mulzer (BM)‐equation which gives the interference effect of fully elongated A/B block copolymers depending on the length distributions of the A‐ and B‐blocks, is specialized onto first‐order Markoff chains as characterized by the transition probabilities pAA, pBB and pAB, pBA for homo‐ and cross‐steps, respectively. The resulting interference function is illustrated by means of simple model calculations. The specilization is applicable to liquid‐crystalline block copolymers in order to analyse the statistical chain character.
Ring‐opening polymerization of cis‐3,4‐dimethoxyoxolane
Authors: Thiem Joachim , Häring Thomas
Published: April 2003

The reaction conditions for the ring‐opening polymerization of cis‐3,4‐dimethoxyoxolane (1,4‐anhydro‐2,3‐di‐O‐methyl‐D‐erythritol, 3) using fluorosulfonic acid as initiator are described. The resulting polyether 4, poly[oxy(2,3‐dimethoxytetramethylene)], is characterized by elucidation of M̄n and M̄w, elemental analysis, 1H NMR spectroscopy as well as terminal group determination. The optimum conditions for obtaining high molecular weight polymers 4 are established and discussed.
Ion exchange and ring‐opening reactions of telechelic poly(tetrahydrofuran)s containing terminal cyclic quaternary ammonium salts
Authors: Tezuka Yasuyuki , Goethals Eric J.
Published: April 2003

Anion exchange and ring‐opening reactions of cyclic quaternary ammonium salt end groups of poly(tetrahydrofuran) [poly(THF)] were studied. The counter anion exchange reaction of the quaternary ammonium triflate to the sulfonate or to the carboxylate, was found to take place by precipitation of the starting poly(THF) prepolymer from an aqueous solution containing the corresponding sodium salt. The azetidinium salt 1 was found to undergo ring opening reaction with its carboxylate counter ion at ambient temperature, whereas the pyrrolidinium salt 2 needs heating up to 100°C. The ring‐opening reactivities of the cyclic ammonium salts of poly(THF) chain ends were compared with those of model systems.
Catalysis by copper complexes of syndiotactic homo‐ and copolymers of Nα‐protected 2‐methylallyl histidinate
Authors: Frey Johann‐Wilhelm , Klein Jakob , Klesper Ernst
Published: April 2003

The syndiotactic Nα‐protected poly(2‐methylallyl L‐histidinate) and the corresponding copolymers, poly[(2‐methylallyl alcohol)‐s‐co‐(2‐methylallyl L‐histidinate)], were complexed with different Cu(II) compounds and used as catalysts for the aerobic oxidation of hydroquinone to quinone. The apparent first order rate constants were one to two orders of magnitude larger for the Cu(II)‐complexed homo‐ and copolymers than for the Cu(II) compounds or the polymers alone, or for the model compound in its complexed or uncomplexed state.
Radius of gyration and hydrodynamic radius of branched polystyrenes in cyclohexane and toluene measured by static and dynamic light scattering
Authors: Murayama Mitsumoto , Okada Mamoru , Fukutomi Takashi , Nose Takuhei
Published: April 2003

The radius of gyration Rg and the hydrodynamic radius Rh for branched (denoted by subscript b) and linear (1) polystyrenes of different molecular weights were measured both in theta‐ and good solvents. The ratios gg ≡ Rgb/Rgl, gh ≡ Rhb/Rhl, and Rh/Rg were calculated and compared with theoretical predictions based on the Kurata‐Fukatsu theory and its extention to good solvent systems. The following observations were made: gg/ggΘ < gh/ghΘ < 1 and (Rh/Rg)1 < (Rh/Rg)b < 1. The expansion coefficients αg and αh are reduced by the incorporation of branching. Theoretical predictions are qualitatively consistent with these results. The second virial coefficient of branched polymers has a larger molecular‐weight dependence than that of linear polymers, which was explained by a smaller molecular‐weight dependence of Rg. The penetration function of branched polymers is about three times as large as that of linear polymers.
Characterization of hydroxy‐terminated polybutadienes by 13C NMR
Authors: Kanakavel Meenakshisundaram
Published: April 2003

Proton noise‐decoupled 13C NMR spectra were used to investigated the sequence distribution of isomeric triads in hydroxy‐terminated polybutadienes (HTPB). The population of nine transcentred and seven cis‐centred triads was calculated from the integrated intensities in the olefinic region. The population of v\documentclass{article}\pagestyle{empty}\begin{document}$\underline{{\rm tc}}$\end{document}/t, c/t\documentclass{article}\pagestyle{empty}\begin{document}$\underline{{\rm tv}}$\end{document} and t\documentclass{article}\pagestyle{empty}\begin{document}$\underline{{\rm tc}}$\end{document}/t triads is higher for HTPB obtained by free radical polymerization than for anionically obtained HTPB. Quantitative data concerning their diad and triad composition were also derived from intensities of the peaks in the aliphatic region. The microstructure calculated from the sum of the population of cis‐ and trans‐centred triads in the olefinic region agrees well with the microstructure computed from the diads and triads of cis(c), trans(t) and vinyl(v) units in the aliphatic region. The methylene and methine carbons in vvv sequences are sensitive to tacticity.
Estimation of the 0th‐order diffusion constant of polydisperse polymer in dilute solution and its application to the “diffusion constant versus molecular weight relationship”
Authors: Okabe Masaru , Ukaji Takeshi
Published: April 2003

A useful method for determining the “diffusion constant vs. molecular weight relationship” for monodisperse polymers is proposed using polydisperse polymers. According to this method, the diffusion constant vs. molecular weight relationship can be established if the 0th‐order diffusion constants are plotted against the 0th‐order molecular weights. The method was tested experimentally by using polydisperse polystyrenes in ethyl methyl ketone at 25°C and in cyclohexane at 35°C (theta‐state). It was ascertained that the diffusion constant vs. molecular weight relationship was well established without any effect of molecular weight distribution even if the polymers were polydisperse.
Kreuzinterferenzen im röntgenkleinwinkeldiagramm von gedehnten segmentierten PU‐elastomeren
Authors: Bonart Richard , Bötzl Franz , Schmid Johann
Published: April 2003

Segmented polyurethane elastomers, when stretched for the first time from the isotropic state, show cross interferences in small angle X‐ray scattering, characterized by an orientation angle which is practically independent of the stretching ratio. This is due to a slip mechanism of plate‐like hard‐segment domains combined with an adjustment of the chain cross sections of hard and soft segments. Furthermore, partial chain folding and, following the hypothesis of force strands, an inhomogeneous deformation process has to be taken into account.
Calixarenes, 19. Studies of the formation of calixarenes via condensation of p‐alkylphenols and formaldehyde
Authors: Dhawan Balram , Chen Shou‐I , Gutsche C. David
Published: April 2003

The base‐induced reaction of p‐alkyl substituted phenols with formaldehyde yields oligomers which, in some cases, are cyclic [1,1,1,1]‐metacyclophames known as calixarenes. The present work attempts to provide insight into the mechanism of calixarene formation by studying various facets of the reaction, including the effect on the product distribution (i.e. cyclic tetramer, cyclic pentamer, cyclic hexamer, cyclic heptamer, and cyclic octamer) of (a) reactant ratios, temperature, solvent, and cation, (b) starting oligomer (i.e. monohydroxymethyl or dihydroxymethyl monomer phenol, dimer phenol, trimer phenol, or tetramer phenol), and (c) p‐alkyl group of the starting phenol. Product analyses were carried out by isolation and TLC methods in some cases and by HPLC methods in others. On the basis of the data that have been obtained it is postulated that (a) the calix[8]arenes are the product of kinetic control and are formed via a hemicalix[8]arene arising from intermolecular association between a pair of hydroxymethylated linear tetramers, (b) the calix[6]arenes are the product, in part, of template control and may be formed via a hemicalix[6]arene anion arising from intermolecular association between a pair of hemicalixarene anions from hydroxymethylated linear trimers, and (c) the calix[4]arenes are the product of thermodynamic control and can be formed via ring contraction of the calix[8]arenes and the calix[6]arenes.
Cationic graft copolymerization of tetrahydrofuran with partially α‐brominated polystyrene
Authors: Cai Gang‐feng , Yan De‐yue
Published: April 2003

Partially α‐brominated polystyrene was first prepared from commercial polystyrene and N‐bromosuccinimide by the Wohl‐Ziegler reaction. It was treated with silver perchlorate to initiate cationic graft copolymerization with tetrahydrofuran leading to polystyrene‐graft‐polytetrahydrofuran. The influence of reaction time, reaction temperature, initial concentrations of silver perchlorate and partially α‐brominated polystyrene, etc., on the graft polymerization was studied. It partially α‐brominated polystyrene with a bromination degree of 5–15% was used, a leather‐like graft copolymer was obtained with a high grafting efficiency at or below 0°C.
Polymerizable amphiphiles, 3. Polymerization of micellized 1‐O‐3‐(4‐vinylphenyl)propyl‐β‐D‐glucopyranose
Authors: Nagai Katsutoshi , Elias Hans‐Georg
Published: April 2003

1‐O‐3‐(4‐Vinylphenyl)propyl‐β‐D‐glucopyranose (1) was polymerized in organic solvents and in aqueous solutions above and below the critical micelle concentration by three different free‐radical initiators: 2,2′‐azoisobutyronitrile (AIBN), dipotassium peroxodisulfate (K2S2O8), and 2‐(phenylazothio)naphthalene (ATE). The polymerization is self‐accelerating in dilute aqueous solutions, regardless of whether oil‐soluble or water‐soluble initiators were used. Size exclusion chromatography was employed to monitor the change of molar masses, molar mass distributions, and conversions with time. The polymerization kinetics was also followed by UV spectroscopy. The polymerization by ATE led to polymerized micelles (P‐mers) under preservation of the degree of micellization. The polymerization by K2S2O8 and AIBN, on the other hand, resulted in the polymerization of bigger micelles (R‐mers) beside a small amount of polymerized P‐micelles.
Facilitated transport of alkali metal picrates through acetylcellulose blend membranes containing synthetic macrolides
Authors: Atsumi Miharu , Okada Masahiko , Sumitomo Hiroshi
Published: April 2003

Permeation of alkali metal picrates through acetylcellulose membranes containing synthetic macrolides (4 and 5) was examined in tris‐buffer solutions (pH 7,8) to evaluate the effectiveness of the macrolides as ion carriers. The macrolides 4 and 5 are 20‐ and 25‐membered macrocyclic oligoesters, respectively, consisting of alternating tetrahydropyran ring and ester moieties, which were prepared by cationic ring‐opening polymerization of 6,8‐dioxabicyclo[3.2.1]octan‐7‐one (1). Ion permeability through the blend membranes increased with increasing macrolide content. The macrolide 5 facilitated ion transport more effectively than the macrolide 4. Dependence of ion permeability on solute concentration in a source phase was analyzed by using Lineweaver‐Burk's equation, and it was revealed that the ion transport through the blend membranes obeyed kinetics of a Michaelis‐Menten type. Ion selectivity sequence for the permeation of alkali metal picrates through the membrane containing 5 was, although not remarkable, Na+ > K+ > Cs+, in sharp contrast to the previously reported ion selectivity sequence for the transport mediated by the macrolides through liquid organic membranes.
Synthesis of new polyamides having in‐chain trans‐1,2‐dicarbazolylcyclobutane units and their spectroscopic properties
Authors: Subramaniam Prema , Sasakawa Tomoyoshi , Ikeda Tomiki , Tazuke Shigeo
Published: April 2003

New polyamides having in‐chain trans‐1,2‐dicarbazolylcyclobutane (DCZB) units were prepared. Fluorescence studies have shown that the fluorescence quantum yields of these polyamides are rather low in comparison with those of DCZB alone and vinyl polymers containing the DCZB units. Furthermore, time‐resolved measurements have revealed that the fluorescence decay of these polyamides can, in general, be analyzed by a triple exponential decay with life times of 1–2 ns (≈20%), 5–6 ns (≈35%), and 12–14 ns (≈45%).
Dynamic viscoelasticity and anomalous thermal behaviour of concentrated agarose gels
Authors: Watase Mineo , Nishinari Katsuyoshi
Published: April 2003

Dynamic viscoelasticity measurements, and differential scanning calorimetry (DSC) were carried out, in order to examine the gelling mechanism of concentrated solutions of agarose with two different molecular weights. The dynamic elastic modulus of the gels increases up to about 35°C and then decreases with increasing temperature. The DSC endothermic peak temperature Tm accompanying the gel‐sol transition was almost independent of the concentration of the gel, which is quite different from the behaviour of many other thermo‐reversible gels. Tm is shifted to higher temperatures with increasing molecular weight of agarose. The endothermic enthalpy was proportional to the concentration of gels for both fractions. A peak characteristic of crystalline material was observed in the X‐ray diffraction pattern of an agarose gel (concentration 15 wt.‐%).
Der interferenzeffekt von gestreckten markoff‐ketten erster ordnung, 2. Einkettenrechnung unter berücksichtigung der atomistischen comonomerstrukturen
Authors: Bonart Richard
Published: April 2003

The interference function of liquid‐crystalline A/B‐block‐copolymers is given. The function is restricted to a one‐chain calculation, i.e. packing effects of neighbouring chains are neglected. It refers to fully elongated first‐order Markoff‐chains with A‐ and B‐sequences, the lengths of which are controlled by the transition probabilities pAA and pBB for A‐A and B‐B steps. Combinations of an A‐ and a B‐sequence each are considered as formal super‐comonomers which follow randomly after each other. Thus, a statistical super‐copolymer not of A‐ and B‐monomers but of A‐ and B‐sequences comes into existence, obeying the interference function as given by Blackwell, Biswas, and Bonart in an earlier paper. Whereas only the reference points of the A‐ and B‐comonomers were considered in the first part of the paper, also the atomistic structures of the comonomers are now taken into account. The result renders the possibility to analyse the chain statistics of liquid‐crystalline copolymers as will be shown in following papers.
Morphology of nylon 6 spherulites in bulk
Authors: Galeski Andrzej , Argon Ali S. , Cohen Robert E.
Published: April 2003

A method of obtaining good quality ultrathin sections from nylon 6 bulk samples has been developed by using a special embedding technique and cryo‐ultramicrotomy. The morphologies of nylon 6 processed by compression and injection molding and of reaction injection molded nylon 6 were studied in ultrathin sections of bulk samples by means of transmission electron microscopy. It was established that the spherulites of nylon 6 in bulk are built up from long flat ribbonlike lamellae. The thickness of the lamellae is in the range 50–60 Å. The width varies from 150 to 600 Å and depends on the type of nylon 6 and the method of processing. The length of the lamellae is relatively large approaching spherulite radii, extending often from the point of their origin up to the spherulite borders. Three or four neighboring lamellae within spherulites usually show similar orientation of their flat faces and form domains which can easily be mistaken for fibrils in light microscopy or low resolution electron microscopy.
Crystallization, melting and morphology of poly(hexamethylene sulfide)
Authors: Sánchez Angeles , Marco Carlos , Fatou José G. , Bello Antonio
Published: April 2003

Poly(hexamethylene sulfide) fractions, ranging in molecular weight from 4600 to 20000, were isothermally crystallized from the melt state in the temperature range 50–70°C. The dependence of the melting temperature on the crystallization temperature was analyzed in experiments involving low and high levels of crystallinity. The equilibrium melting temperature corresponds to 366 K and the enthalpy of fusion was found to be 40,5 cal/g (= 170 J/g). The isothermal overall crystallization rates were analyzed using dilatometric and calorimetric techniques. The Avrami exponent is an integral value, n = 3, and the crystallinity varies with increasing molecular weight from 65% to 55%. The morphology is spherulitic and it was found that the growth rate is linear in the whole range of crystallization temperatures. The temperature coefficient of the crystallization was analyzed using nucleation theory, and comparison between dilatometric and growth data revealed that the overall rate and growth rate‐temperature coefficients are approximately equal.
Thermotropic polyesters, copolyesters and model compounds based on terephthalic acid and 4,4′‐alkylenediphenols
Authors: Fradet Alain , Heitz Walter
Published: April 2003

Main chain thermotropic polyesters 1a and 1b and random copolyesters 1ab, based on terephthalic acid and 4,4′‐hexamethylenediphenol (5a) or 4,4′‐decamethylenediphenol (5b) were synthesized in good yields by a solution reaction in presence of benzenesulfonyl chloride. A mechanism is discussed. Low molar mass models 4a and 4b and oligomers 2a, 2b, 3a and 3b, with the same mesogenic unit and end groups comparable to the spacers used in polymers 1, were synthesized and their liquid‐crystalline properties compared to those of polymers. Models with at least two mesogenic units and polymers exhibit both smectic and nematic mesophases. Increasing spacer length decreases dramatically the stability of the nematic mesophases, but lowers only slightly the melting points. The phase diagram for random copolyesters 1ab were determined by DSC. Broad endotherms with overlapping multiple peaks were found for most of the copolymers. Monomeric units of 1a and 1b cocrystallize in 1ab, which leads only to slight melting point depression. The variations of nematic‐isotropic transition versus composition of copolymers are linear, while the smectic phase stability appreciably decreases.
Syntheses and characterization of terminally functionalized polypropylenes
Authors: Doi Yoshiharu , Hizal Gürkan , Soga Kazuo
Published: April 2003

Functional polypropylenes having vinyl, phenyl or hydroxyl groups at the chain end were prepared by adding common monomers as butadiene, styrene and 1,2‐epoxypropane, respectively, at −78°C during the living coordination polymerization of propene with a soluble V(acac)3/Al(C2H5)2Cl catalyst. In addition, polypropylene with hydroxyl functions was prepared by an alternative method based on the hydrogenation of a polypropylene containing aldehyde functions with LiAlH4. These new types of terminally functionalized polypropylenes were well‐characterized by 1H NMR analysis.
Hydrolysis of phenyl esters in cyclodextrin‐polymer systems
Authors: Seo Toshihiro , Kajihara Taketoshi , Iijima Toshiro
Published: April 2003

The catalytic hydrolysis of phenyl esters in systems containing ß‐cyclodextrin (ß‐CD) and polyelectrolytes was investigated. Poly(methacrylic acid) was found to exhibit an inhibition effect on the hydrolysis, while poly(sodium styrenesulfonate) (NaPSS) shows a pronounced acceleration effect on the hydrolysis: the larger the molecular weight and the lower the degree of substitution, the greater is the acceleration effect. On the other hand, sodium ethylbenzenesulfonate and sodium dodecylbenzenesulfonate inhibit the reaction. The acceleration of the reaction in presence of NaPSS is attributed to the concentration of ß‐CD and the substrate esters near to the chain of the macromolecule, through inclusion effects and hydrophobic interactions.
Une méthode d'immobilisation d'anticorps par liaisons covalentes sur nylon 66. Application en test immunoenzymatique
Authors: Couturier Roger , Ville Albert , Perrin Bernard , Favre‐Bonvin Guy
Published: April 2003

A new method of immobilization of low‐molecular‐weight compounds or antibodies on nylon 66 was developed. Secondary amide groups of nylon 66 were converted into secondary imidate groups by O‐alkylation with sulfuric acid and methanol. The methoxycarbonimidoyl groups react with amino compounds to produce stable amidine links. Antibodies and several low‐molecular‐weight compounds (amino acids) were immobilized by covalent linkage on nylon balls. Fixed antibodies were used in solid phase enzyme linked immunoassay, i.e. applied for the detection of K99+ Escherichia Coli in calves.