bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of isotopically labelled monomers and polymers of 4‐hydroxybenzoic acid and 6‐hydroxy‐2‐naphthoic acid
Authors: Nieβner Norbert , Mühlebach Andreas , Lyerla James R. , Facey Glenn A. , Fyfe Colin A.
Published: April 2003

Synthesis and characterization of 4‐acetoxybenzoic acid and 6‐acetoxy‐2‐naphthoic acid, labelled with deuterium in the rings and with carbon‐13 and oxygen‐17 in the carboxyl‐positions, and of the corresponding homo‐ and copolyesters, are described. Kinetic studies of hightemperature deuteration were performed on 6‐hydroxy‐2‐naphthoic acid. Mass spectrometry provides information about the degree of labelling with 2H, 13C and 17O. Composition and molecular weight of isotopically labelled polymers were monitored by 1H NMR after digestion in basic methanol. The thermal behavior was investigated by differential scanning calorimetry and thermogravimetry.
Die katalyse der 1,4‐cis‐polymerisation des butadiens mit dem kationischen C12‐allylnickel(II)‐komplex [Ni(C12H19)]SbF6
Authors: Taube Rudolf , Langlotz Jochen
Published: April 2003

The catalytic properties of η3,η2η2‐dodeca‐2(E),6(E),10(Z)‐trien‐1‐yl‐nickel(II) hexafluoroantimonate are investigated in some detail. Under standard conditions the complex catalyses the polymerization of butadiene in toluene at room temperature with an extremely high activity of nearly 15000 mol C4H6/(mol Ni · h) and a cis selectivity up to 90%. The activity increases linearly with both the nickel and the butadiene concentration. No change in the selectivity and in the limiting viscosity number [n] has been found in the investigated range of concentration and temperature.
Polylactones, 22 ABA triblock copolymers of L‐lactide and poly(ethylene glycol)
Authors: Kricheldorf Hans R. , Meier‐Haack Jochen
Published: April 2003

Triblock copolymers were prepared from L‐lactide and a poly(ethylene glycol) of M̄n = 1020. With GeO2 and SnO2 only low conversions were obtained, regardless of the reaction temperature. Sb2O3 caused partial racemization, and only SnO gave satisfactory results. When other samples of poly(ethylene glycol) were used (e.g., with M̄n = 600 or 3250), partial racemization occurred even with SnO. However, with Sn(II) 2‐ethylhexanoate, racemization‐free triblock copolymers were obtained under the reaction conditions used. The results of the characterization indicate that the triblock copolymers possess unimodal molecular weight distribution. The lactide blocks crystallize in the α‐modification and suppress in most, but not all, cases the crystallization of the poly(ethylene glycol) blocks. The crystallization of long poly(ethylene glycol) blocks observed in several cases indicates a triphasic character of these samples.
The thermal behaviour of low‐molecular‐weight poly(3‐decylthiophene)
Authors: Bolognesi Alberto , Porzio William , Provasoli Francesco , Ezquerra Tiberio
Published: April 2003

A detailed study on the thermal behaviour of low‐molecular‐weight poly(3‐decylthiophene) (Mw = 5700 by gel permeation chromatography) was performed using differential scanning calorimetry, X‐ray diffraction, optical microscopy and FTIR techniques. A polymorphism for this polymer was clearly shown: namely two different crystalline phases and a mesophase, probably nematic. A structural model for a 3‐dimensional phase was derived. Finally the conditions under which each phase can be obtained were determined.
Acetylene‐terminated amide oligomers
Authors: Martinez Francisca , de Abajo Javier , Mercier Regis
Published: April 2003

Six new acetylene‐terminated (AT) oligomers were synthesized by reaction of 3‐ethynylbenzoyl chloride and 4‐ethynylbenzoyl chloride with three aromatic diamines containing four aromatic rings. The functionalization led quantitatively to AT oligomeric diamides of well defined composition, as confirmed by IR, 1H NMR and 13C NMR spectroscopy. The materials exhibited comparatively high melting points, over 200°C; thus, heating promoted curing before melting or simultaneously with melting, with the only exception of one sample that could be isolated in the amorphous state. Heating at 325°C led to insoluble cured materials, with excellent thermal resistance and glass transition temperatures Tg around 300°C.
Influence of the block length on the structure of micelles formed by polystyrene‐block‐poly(ethylene‐co‐propene) in octane and 5‐methyl‐2‐hexanone
Authors: Quintana José R. , Villacampa Manuel , Katime Issa A.
Published: April 2003

The influence of molar mass and chemical composition of the copolymer on the structural parameters of copolymer micelles was investigated. Two polystyrene‐block‐poly(ethylene‐co‐propene) copolymers with the same polystyrene block length but different poly(ethylene‐co‐propene) length were used. The micelles were studied in solutions of octane and 5‐methyl‐2‐hexanone, selective solvents for poly(ethylene‐co‐propene) (PEP) and polystyrene (PS) blocks, respectively. Static light scattering and viscosity measurements were carried out in order to determine the weight‐average molar mass, radius of gyration, second virial coefficient and hydrodynamic radius of the micelles. The association number of the micelles depends on the location of the largest copolymer block in the micelle structure. An influence of the copolymer structure on the micelle dimensions was also found.
Syntheses and properties of polyamides from glucosamine and glucose derivatives
Authors: Thiem Joachim , Bachmann Frank
Published: April 2003

Starting from D‐glucosamine, the synthesis of various differently modified methyl and benzyl 2,6‐diaminosaccharides 11, 12, 17 and 18 was accomplished. Interfacial and solution polycondensation of those diamino derivates with aromatic and aliphatic acyl chlorides yielded polyamides 34, 35, 36 and 37a–d which were characterized by 1H NMR spectroscopy and their inherent viscosities. The presence of an anomeric benzyl group in 12 did not decrease the reactivity of the 2‐amino function. The free hydroxy functions in polyamides 35a–b were acetylated to give polyamides 39a–b. Partially blocked polyamides 36a–d had similar properties as unprotected polyamides 34–35a–d. Under corresponding conditions di‐O‐acylated diaminosaccharide 18 gave only oligomer. Number‐average molecular weights were obtained from gel‐permeation chromatography to be 10300 < M̄n < 24000 (interfacial polycondensation), corresponding to number‐average degrees of polymerization up to P̄n = 64, whereas polycondensation in solution afforded only M̄n values between 2000 and 3000. Starting with D‐glucose the synthesis of a C‐glycosidic diaminosaccharide 28 was developed. This reacted to polyamides 38a–d which showed thermal stability up to 280°C.
Polyéthers aromatiques à motifs azoïques, 2. Note sur I'hétéropolycondensation en milieu basique du azobenzène‐4,4′‐diol avec le 1,4‐bis(chlorométhyl)‐2,5‐diméthylbenzène
Authors: Radu Stelian
Published: April 2003

The influence of the concentration of the reactants (bis(chloromethyl) derivative, NaOH) and of the reaction time upon the intrinsic viscosity and the yield of the polymers synthesized by the heteropolycondensation of sodium azobenzene‐4,4′‐diolate with 1,4‐bis(chloromethyl)‐2,5‐dimethylbenzene is presented. The optimum conditions of polymer synthesis are established.
Synthesis of uniform poly(aspartic acids)
Authors: Rao Vanga S. , Lapointe Philippe , McGregor Donald N.
Published: April 2003

Poly(aspartic acids) of different chain lengths (11, 14, 18, 24, 30, 52, 58, ≈ 115) were prepared, for the use in aminoglycoside‐induced nephrotoxicity inhibition studies, some in their pure L‐ or D‐configuration and in pure α‐linkage form by the polymerization of α‐amino acid N‐carboxyanhydride (NCA) derivatives with a variety of dialkyl aspartate molecules as primary amine initiators. The primary amine chosen served as an internal reference in the 1H NMR spectrum for the estimation of the degree of polymerization (chain length) in these molecules. Poly(aspartic acids) with varying amounts of D and L asymmetric centres and in pure α‐linkage from were also prepared. Poly[(α‐co‐β)(L‐co‐D) aspartic acid] was prepared by a simplified thermal polymerization procedure for biological studies and also to study the tacticity effects in its 13C NMR spectrum. A qualitative correlation was demonstrated between the retention times from gel‐permeation chromatographic analysis and the 1H NMR method used to estimate the polymer chain length.
New polymer syntheses, 64. Thermotropic polyesters derived from 4,4′‐biphenyldiol and terephthalic acids with one long aralkoxy side chain
Authors: Kricheldorf Hans R. , Bürger Rolf
Published: April 2003

A new class of monosubstituted terephthalic acids was prepared from commercial dimethyl nitroterephthalate by a three‐step procedure. This procedure consists of the nucleophilic substitution of the nitrogroup by 4‐mercaptophenol followed by alkylation of the phenolic OH group and saponification of the dimethylester groups. Four polyesters were prepared by polycondensation of 4,4′‐biphenyldiol or its bis(trimethylsilyl) ether with four new substituted terephthaloyl chlorides. The “silyl method” was found to give the highest molecular weights. All polyesters are semicrystalline and form nematic melts. In three cases the melting points range from 250 to 275°C. All polyesters are soluble in a variety of organic solvents.
Copolymers of ethyl p‐vinylbenzenesulfonate for the preparation of polyelectrolytes of reproducible ion content
Authors: Woeste Govert , Meyer Wolfgang H. , Wegner Gerhard
Published: April 2003

Ethyl p‐vinylbenzenesulfonate (ESS) for which a new synthesis is described has been copolymerized with vinylcarbazole, styrene, p‐methylstyrene and p‐bromostyrene in N,N‐dimethylformamide at 60°C using azoisobutyronitrile as initiator. Copolymer compositions and copolymerization parameters have been evaluated. Q, e‐values for ESS are 4,19 and ‐0,11. Thermal properties of the copolymers have been investigated by differential scanning calorimetry and thermogravimetric analysis. Polyelectrolytes have been prepared either by polymer analogous hydrolysis of the sulfonic acid esters followed by conversion of the free acids into alkali metal salts or by using the alkylating properties of the esters towards tertiary amines or pyridines to form the appropriate sulfonic acid ammonium or pyridinium salts. The latter method offers the opportunity to synthesize polyelectrolytes with a well defined content of chromophores.
Stopped‐flow fourier transform infrared studies in polymer chemistry
Authors: Brittain William J. , Aquino Eugene C. , Dicker Ira B. , Brunelle Daniel J.
Published: April 2003

The application of stopped‐flow FT‐IR spectroscopy to group transfer polymerization (GTP) and cyclic oligomeric carbonate formation is described. The influence of catalyst structure, propagating end stereochemistry and degree of polymerization (DP) on the rate of monomer addition was examined for GTP. Also, the major GTP termination process was identified and characterized. Model reactions were used to study the kinetics of acyl ammonium salt formation and subsequent conversion to urethane. These results were used to further develop the mechanism of bisphenol A‐bischloroformate macrocyclization.
Chemical structure of plasticizers, compatibility of components and phase equilibrium in plasticized cellulose diacetate
Authors: Suvorova Anna I. , Demchik Lyudmila Yu. , Peshekhonova Aza L. , Sdobnikova Olga A.
Published: April 2003

The phase equilibrium of plasticized polymer systems on the basis of cellulose diacetate and ethylene glycol esters of dibasic aliphatic acids (from oxalic acid to 1,10‐decanedicarboxylic acid) was studied and the solubility parameters and the thermodynamic interaction parameters of the components were calculated. It is shown that an increase in molecular weight of the plasticizers leads to a lower miscibility of the components, a fact which is reflected in a regular rise of the upper critical solution temperature (UCST), a tendency of the systems for gelation, a decrease of the solubility parameter of the plasticizer δ1, and a growth of the interaction parameters χH and χ12. The results are discussed in terms of the existing theories for polymer solutions.
The role of additives for the improvement of δ‐TiCl3 catalyst performance
Authors: Maria Luiz Claudio de Santa , Coutinho Fernanda M. B. , Alencar Cláudia
Published: April 2003

The influence of ethylaluminium compounds (AIEt3 and AICIEt2) modified by 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT), tributylamine (TBA) and triphenylphosphine (TPP) on the polymerization of propene was investigated using catalysts based on TiCI3 modified by internal Lewis bases. Two catalysts were employed in this study, one (Cat. A) was prepared by the reduction of TiCI4 complexed with dibutyl ether (DBE)—mole ratio DBE/TiCI4 = 0,67—with AlClEt2 and the other one (Cat. B) was prepared in the same way, but a second internal base (ethyl benzoate (EB)) was added in a mole ratio EB/TiCl3 = 0,04. Activity and stereospecificity of the catalyst systems were strongly affected by these modified cocatalysts. The role of the modifiers is discussed.
Intramolecular interaction of chain molecules: Second osmotic virial coefficients and intrinsic vicosities
Authors: Wolf B. A.
Published: April 2003

In a new theoretical approach the separation of a pair of chain molecules (measured thermodynamically by the second osmotic virial coefficient A2) is treated as a two‐step process: In the first step the molecules are detached from each other by the addition of solvent—keeping their dimensions constant—and in the second step the now isolated coils are allowed to relax into their equilibrium dimensions. For the description of the second step, in which only segments belonging to one molecule take part, an intra‐molecular interaction parameter is introduced on the basis of the intrinsic viscosity. The present two‐parameter approach yields A2 = A + σ M−(1−a) for the dependence of A2 on the molecular weight M of the polymer; a is the exponent of the Kuhn‐Mark‐Houwink equation and σ a parameter measuring the effects associated with the second step (becoming zero if the coil dimensions do not depend on polymer concentration). A test of the above relation by means of published material demonstrates its superiority over other two parameter theories: It can describe the actually measured A2(M) well down into the region of oligomers without an additional parameter and it comprises the conceptual advantage of explaining experimental observations concerning ∂A2/∂M > 0 or ∂A2/∂M ≈ 0 for high A2 values.
Non‐destructive determination of the residual monomer content in polymers by Raman spectroscopy
Authors: Dywan Frank , Hartmann Brigitte , Klauer Stefan , Lechner Manfred D. , Rupp Romano A. , Wöhlecke Manfred
Published: April 2003

By a comparative study and by calibration, Raman spectroscopy is established as a non‐destructive method for the determination of the monomer concentration in solid poly(methyl methacrylate) samples. Although the effect of the internal field on the refractive index and on the Raman intensity of a polymer solution in a monomer is considered, the Raman scattering cross section of the carbonyl stretching vibration of the monomer turns out to be more than twice as large as that of the polymer.
Composites from furfuryl alcohol and inorganic solids by cationic initiation, 2. Spectroscopic studies of poly(furfuryl alcohol)‐silica composites obtained by trifluoroacetic acid initiation
Authors: Spange Stefan , Schütz Heidrun , Martinez Ricardo
Published: April 2003

Furfuryl alcohol polymerizes in a suspension of dispersed inorganic solids such as silica in 1,2‐dichloroethane using trifluoroacetic acid as initiator. Depending on the experimental conditions the reactions load to (1) agglomeration of particles, (2) composite and soluble polymer formation, (3) composite formation. The chemical structure of the soluble polymers is not regular but the furfurylic sequence is predominant. The polymer grafted on the surface of the solid is a strongly reticulated poly(furfuryl alcohol), which also possesses conjugated double bonds that are involved in an acid‐base equilibrium with trifluoroacetic acid.
Linear‐temperature programmed pyrolysis of thermoresistant polymers — mass and FTIR spectrometries, 2. Aromatic polyesters and copolyesters
Authors: Hummel Dieter O. , Neuhoff Ulrich , Bretz Anke , Düssel Heinz‐Jürgen
Published: April 2003

Linear‐temperature controlled pyrolysis with subsequent analysis of the pyrolyzates (volatiles and residue) by 18 V electron‐impact mass spectrometry (EIMS) and FTIR spectrometry, respectively, yields optimal informations on the thermal degradation mechanisms of heat‐resistant polymers. In the present paper results with aromatic polyesters are reported. Poly(4‐oxybenzoyl) firstly (675 K) releases residual educt (acetoxybenzoic acid), solvent (hexahydroterphenyl), phenol and oligomers. In the temperature range of maximum decomposition (Tmax = 815 K) several consecutive processes take place. At 760 K, “monomer” (oxybenzoyl) and two series of oligomers with different endgroups are set free. At 815 K, formation of phenol, and at 845 K. formation of diphenyl ether are the dominating process. The maxima of CO2 and CO release are at 790 K and 825 K, respectively. In the residue, diaryl ketone, 9‐fluorenone and phenolic structures were observed. Mechanisms including Fries‐analogue rearrangements are discussed. A typical poly‐(4‐oxybenzoyl‐ran‐2‐oxy‐6‐naphthoyl) (“Vectra A 950”) with 73 mol‐% oxybenzoyl units produced, during the “evaporation phase” (640 K) and in addition to oxybenzoyl “monomer” and oligomers, oxynaphthoyl and a series of hetero‐fragments containing one oxynaphthoyl unit and one or two oxybenzoyl units. At 785 K (close to Tmax), the formation of phenol, CO2, CO and oxybenzoyl was predominant. In the residue, the formation of diaryl ketone, dibenzofuran and 9‐fluorenone structures was observed. Mechanisms are discussed in analogy to the degradation of poly(4‐oxybenzoyl).
Polylactones 26. Lithium alkoxide‐initiated polymerizations of L‐lactide
Authors: Kricheldorf Hans R. , Boettcher Caroline
Published: April 2003

Lithium alkoxide‐initiated polymerizations of L‐lactide were conducted in toluene at 50°C. The initiator solutions were prepared in situ from butyllithium and benzyl alcohol, 1‐tetradecanol, diethylene glycol monobutyl ether or poly(ethylene glycol) monomethyl ether. These lithium alkoxides initiate the polymerization via nucleophilic attack, forming alkyl ester end‐groups as evidenced by 1H NMR spectroscopy. High yields, high molecular weights and a relatively high optical purity (up to 95%) of the isolated poly(L‐lactide) may be obtained.
Evaluation of the kinetic parameters for styrene polymerization and their chain length dependence by kinetic simulation and pulsed laser photolysis
Authors: Deady Mark , Mau Albert W. H. , Moad Graeme , Spurling Thomas H.
Published: April 2003

Pulsed laser photolysis (PLP) has been employed to determine propagation rate constants kp for styrene polymerization in benzene over a wider temperature range (20−80°C) than previously converd. It is proposed that a small chain length dependence of kp (overall) may, in part, be a consequence of a marked chain length dependence of kp for the first few propagation steps [i.e. kp(1) > kp(2) < kp(3) ≥ kp(≥4)]. The propagation rate constant for styrene polymerization is given by the expression: In kp = 16,09 − 28950/(RT) (overall) or In kp = 16,47 − 30084/(RT) (chain length ≥ 4). Kinetic simulation has been applied both as an aid in data analysis and to demonstrate the reliability of the PLP technique for evaluation of propagation rate constants (kp) in radical polymerization. This has been achieved by examining the sensitivity of the molecular weight distribution of polymers formed in PLP experiments to the values of the kinetic parameters associated with polymerization and their chain length dependence. The termination rate constants (kt = kc + kd) and the ratio of combination to disproportionation (kc: kd) markedly affect the molecular weight distribution of polymer formed in PLP experiments. The prospects for evaluating the values of kt, its chain length dependence and kc : kd by direct analysis of the molecular weight distribution are discussed in the light of these results.
Kinetic and ESR studies on the radical polymerization. radical‐initiated copolymerization of the diethyl itaconate‐SnCl4 complex and styrene
Authors: Nakamura Hiroyuki , Seno Makiko , Tanaka Hitoshi , Sato Tsuneyuki
Published: April 2003

The copolymerization of diethyl itaconate(1) (M1) and styrene (2) (M2) with dimethyl 2,2′‐azoisobutyrate (3) was performed in benzene at 50°C, and the following copolymerization parameters were obtained: r1 = 0,34, r2 = 0,35, Q1 = 0,93 and el = +0,66. The copolymerization system was found to involve ESR1

Electron spin resonance.

‐observed propagating polymer radicals at low monomer feed composition (f2) of 2. The apparent rate constant of termination increased rapidly with f2. The ESR‐determined values of the apparent propagation rate constant of the copolymerization were lower than those calculated on the basis of the Mayo‐Lewis model, suggesting a significant penultimate effect in the copolymerization. On the other hand, the copolymerization of the 1‐SnCl4 complex (M1) and 2 (M2) at 50°C yielded a nearly alternating copolymer independently of the monomer feed composition. The propagating polymer radicals were ESR‐observable even up to f2 = 0,8. The ESR‐determined apparent rate constant (kp) of propagation showed a maximum near f2 = 0,5. From the relationship between kp and f2, the rate constants of cross‐propagations of the present alternating copolymerization were evaluated as k12 = 483 and k21 = 510 L. mol−1 · s−1. Comparison of the k21 value and the reported propagation rate constant (209 L · mol−1 · s−1) of homopolymerization of 2 leads to the conclusion that the alternating copolymerization via free‐monomer propagation mechanism originates from a pronounced penultimate effect suppressing homopropagation of 2, but not from enhanced cross‐propagation.
Studies of the autoxidation of phenols catalyzed by the cobalt(II) complex of disodium N,N′‐bis(salicylidene)‐ethylenediamine‐5,5′ ‐disulfonate bound to colloidal anion exchange resin
Authors: Hassanein Mahmoud , Aly El‐Saied A. , Abbas Yousf A. , El‐Sigeny Samia M.
Published: April 2003

To overcome mass transfer limitations which are usually encountered on immobilizing active catalysts, cationic latex particles were used as support for the cobalt(II) complex of disodium N,N′‐bis(salicylidene)ethylenediamine‐5,5′‐disulfonate (1). The cationic latex 2 was prepared by emulsion copolymerization of chloromethylstyrene (m/p‐isomer mixture 60/40) and divinylbenzene (m/p‐isomer mixture) followed by treatment with trimethylamine. The latexbound catalyst from 1 and 2 was found to considerably increase the reaction rate of the autoxidation of 2,6‐di‐tert‐butylphenol in water as compared with the conventional polymer‐free system. Reaction products were identified as the oxidative coupling product 3,3′,5,5′‐tetra‐tert‐butyldiphenoquinone (3,3′,5,5′‐tetra‐tert‐butyl‐4,4′‐dioxo‐1,1′‐bicyclohexa‐2,5‐dienylidene) and 2,6‐di‐tert‐butyl‐1,4‐benzoquinone. All reactions showed an induction period before the start of dioxygen consumption. The rate of autoxidation in the three‐phase mixtures of water, latex particles, and phenol droplets was not affected significantly by the method of mixing. The reaction rate increased as the concentration of 1 increased. Increasing the partial pressure of dioxygen in the range between 0,25 and 1,0 atm (2,53. 104 – 1,01. 105 Pa) gave a small increase in rate. The colloidal latex catalyst from 1 and 2 showed some loss of activity after successive runs.
Synthesis of crowned initiators and kinetic studies of crowned benzophenone‐sensitized photopolymerization of methyl methacrylate
Authors: Yuan Lihua , Tian Baozhi , Huang Shu
Published: April 2003

A series of crowned benzophenones (CBPs) and benzoins was synthesized. Application of CBPs as initiators for the photopolymerization of methyl methacrylate (MMA) indicated a kinetic similarity between benzophenones and crowned benzophenones. With CBPs a rate enhancement was observed which was attributed to the higher light absorptance in the presence of crown ether structure. UV spectra confirmed the existence of the crown species as end groups of the polymer chains.
Highly crosslinked chitosan gels
Authors: Tikhonov Vladimir E. , Yamskov Igor A. , Davankov Vadim A.
Published: April 2003

Chitosan was crosslinked to varying extents with bis(vinylsulfonyl)arenes as crosslinking agents in homogeneous solution. The effect of reaction conditions on the onset of gelation was investigated. The rate of gelation was shown to depend on the chitosan concentration and the structure of the crosslinking agent used. The degree of crosslinking and content of the remaining pendant double were evaluated. The obtained cnitosan gels swell both in organic solvents and in acidic aqueous solutions.
Copolymerization and copolymers of N‐(2,4,6‐tribromophenyl)maleimide with methyl acrylate and methyl methacrylate
Authors: Janović Zvonimir , Matusinović Tomislav T. , Ranogajec Franjo
Published: April 2003

N‐(2,4,6‐Tribromophenyi)maleimide (TBPMI) was copolymerized with methyl acrylate (MA) or methyl methacrylate (MMA) in toluene solution using 2,2′‐azoisobutyronitrile as free‐radical initiation. The copolymerization reactivity ratios were found to be for the system TBPMI/MA r1 = 0,095 ± 0,045 (TBPMI) and r2 = 2,17 ± 0,142 (MA) and for the system TBPMI/MMA r1 = 0,037 ± 0,042 (TBPMI) and r2 = 4,32 ± 0,230 (MMA); Q and e values were also calculated. The initial rate of copolymerization, Rp, for TBPMI/MA sharply decreases as the content of TBPMI in the monomer mixture increases but the composition of the feed does not have a strong influence on Rp for the TBPMI/MMA copolymerization system. The course of copolymerization to high conversion is characterized by an increase of conversion up to a mole fraction of TBPMI of 0,7 in the monomer mixture, when MA was used as the comonomer. An opposite behaviour was found with MMA. Its copolymers show a considerable increase of thermal stability as well as of the glass transition temperatures with increasing TBPMI content.
Multi‐detector size‐exclusion chromatography: a novel approach to calibration eliminating lag time estimation
Authors: Suddaby Kevin G. , Sanayei Ramin A. , O'Driscoll Kenneth F. , Rudin Alfred
Published: April 2003

In order to obtain the correct calibration of molecular‐weight sensitive detectors (such as on‐line viscometers or light scattering detectors) in size‐exclusion chromatography, it is necessary to account for the (molecular) non‐uniformity of the calibration standards. This is true even in the case of the narrow molecular weight distribution standards typically commercially available for calibration. Methods of taking this non‐uniformity into consideration are presented. For a multi‐detector size‐exclusion chromatography system calibrated in this way, independent calibration curves can be established for each detector. Thus, at a given hydrodynamic volume, corresponding signals from the different detectors can be obtained. This eliminates the need to estimate additional parameters such as interdetector volumes or lag times for matching signals from different detectors. The practicability of this approach in the analysis of (molecularly) non‐uniform polymers is demonstrated by combining on‐line viscometer and concentration signals (to obtain intrinsic viscosity versus molecular weight information) for two different polymers, viz. polystyrene and poly(methyl methacrylate). The resultant intrinsic viscosity versus molecular weight data is then compared to that predicted from the literature.
Temperature‐responsive graft copolymers for immobilization of enzymes
Authors: Takeuchi Shigeya , Omodaka Izumi , Hasegawa Kiyoshi , Maeda Yasushi , Kitano Hiromi
Published: April 2003

A graft copolymer was prepared by coupling of poly(acrylic acid‐co‐acrylamide) (monomer ratio 1:8,5) with poly(N‐isopropylacrylamide) (PIPA) having an amino group at its end. The copolymer with the graft chains obtained [poly(AA‐co‐AAm)‐g‐PIPA] showed a temperature‐responsive phase transition at 34°C in water, and at 26°C in 1‐propanol/water (8:92 vol.‐%). Lipase from wheat germ was covalently bound to the graft copolymer using a water‐soluble carbodimide. The Arrhenius plots of the catalytic activity of the lipase immobilized to poly(AA‐co‐AAm)‐g‐PIPA had a bending point around 25 – 30°C in 1‐propanol/water (8:92 vol.‐%), which is consistent with the temperature‐responsiveness of the carrier polymer. As for lipase immobilized to the graft copolymer poly(AA)‐g‐PIPA, on the contrary, there was no bending point in the temperature dependence of the catalytic activity, probably due to electrostatic repulsion between acrylic acid residues, which perturbs the aggregation of PIPA side chains. The graft copolymer prepared here can be used as a component of temperature‐sensitive devices in various forms.
Gas transport properties of linear and crosslinked side‐chain liquid crystalline polymers with variable spacer lengths
Authors: Chen Deng‐Shan , Hsiue Ging‐Ho
Published: April 2003

A series of side‐chain liquid crystalline polymers (side‐chain LCPs) with different flexible spacer lengths and various degrees of crosslinking were synthesized and characterized. The transport properties of O2, N2, CO2 and CH4 in these polymers were measured by using permeation and sorption methods. The values of diffusion and solubility coefficients were found to be significantly affected by the crosslinking reaction. In contrast to conventional crosslinked polymers, the values greatly increase as the degree of crosslinking increases. The reason might be the use of the flexible oligodimethylsiloxane crosslinking agent and the low solubility of gases in the liquid crystalline regions. The transport properties were also demonstrated to depend strongly on the flexible spacer length. This was ascribed to the fact that different liquid crystalline phases are formea. For the smectic phase, the diffusion and solubility coefficients are lower than those found in the nematic one.
Copolymerization of ethylene and propene with a TiCl4/MgCl2‐Al(C2H5)3 catalyst system using a stopped‐flow method
Authors: Soga Kazuo , Ohgizawa Masa‐aki , Shiono Takeshi
Published: April 2003

Copolymerization of ethylene with a small amount of propene was conducted with a TiCl4/MgCl2‐Al(C2H5)3 catalyst system using a stopped‐flow method. With an increase in the polymerization time from 0,035 to 0,145 s, the copolymer yield increases linearly but the number‐average molecular weight of the copolymer showed a tendency of saturation. The rate constants of the propagation reaction as well as the concentrations of active sites were estimated using these data. On the other hand, the 1H NMR spectra of copolymer did not display the resonances due to CC double bonds which should be formed by chain transfer with monomer and/or by β‐hydrogen elimination. It was also found that the crystallinity of the copolymer decreases to a great extent upon incorporation of even a very small quantity of propylene units. From these results, it was concluded that the apparent rate of copolymerization is not controlled by monomer diffusion through the polymer films. Rather the transfer reaction with Al(C2H5)3 might predominantly take place during the copolymerization.
Transport properties of polyphosphates related to natural teichoic acids
Authors: Wódzki Romuald
Published: April 2003

The paper deals with transport functions of natural polyphosphates, i.e. wall‐and lipoteichoic acids (WTA, LTA) appearing in Gram‐positive bacteria. The results concerning the separation of magnesium and calcium ions in a membrane system, simulating bacteria cell wall, are presented. The system was composed of a solid polymer membrane and a liquid membrane, containing poly(trimethylene phosphate) and α‐hydroxy‐ω‐(2‐ethylhexyl)‐poly(trimethylene phosphate) applied as synthetic analogues of WTA and LTA, respectively. Up‐hill transport with reference towards magnesium ions was observed.
Kinetic and ESR studies on radical polymerization. ESR and kinetic evidences for the penultimate effect in the radical‐initiated copolymerization of N‐cyclohexylmaleimide and bis(2‐ethylhexyl) itaconate in benzene
Authors: Sato Tsuneyuki , Kawasaki Shinji , Seno Makiko , Tanaka Hitoshi , Kato Kenji
Published: April 2003

The copolymerization of N‐cyclohexylmaleimide (1) (M1) and bis(2‐ethylhexyl) itaconate (2) (M2) with dimethyl 2,2′‐azoisobutyrate (3) as an initiator was carried out at 50°C in benzene. Monomer reactivity ratios were estimated as r1 = 0,34 and r2 = 0,38. The copolymerization rate (Rp) and the molecular weight of the resulting copolymer increased with increasing concentration of 1 when the total concentration of comonomers was fixed at 1,00 mol. L−1. Rp was proportional to [3]0,5, indicating a usual bimolecular termination in the copolymerization. An electron spin resonance (ESR) spectrum of the propagating polymer radicals was observable in the actual copolymerization system at 50°C. The spectrum of the copolymerization system is inexplicable in terms of any superposition of spectra observed in the corresponding homopolymerization systems, revealing that some penultimate monomeric unit causes a change in the ESR spectrum, that is, the structure of propagating polymer radical. The apparent rate constant of propagation (kp) and termination (kt) were estimated by ESR. The kp values (1,5–50 L · mol−1 · s−1) are fairly higher than those estimated on the basis of the terminal model, affording another piece of evidence for the penultimate effect. The kt value (1,8–5,4·103 L · mol−1 · s−1) shows a behaviour similar to that of the intrinsic viscosity of the resulting copolymer on varying the monomer feed composition, which seems to reflect diffusion‐control of termination reactions.
Multiblock poly(ether‐ester‐amide)s based on polyamide‐6 and poly(ethylene glycol), 2 Effect of composition and soft‐segment length on the structure of poly(ether‐ester‐amide)s as revealed by X‐ray scattering
Authors: Apostolov Anton A. , Bosvelieva Eliana , Du Chesne Alexander , Goranov Konstantin , Fakirov Stoyko
Published: April 2003

Isotropic unannealed and annealed melt‐pressed and quenched samples of segmented multiblock poly(ether‐ester‐amide)s based on polyamide‐6 and poly(ethylene glycol)s (PEGs) of molecular weights 400 and 1000 with various hard/soft segment weight ratios were investigated. The effect of composition, segment length and annealing temperature on the crystal structure was studied by differential scanning calorimetry, wide‐angle and small‐angle X‐ray scattering. In addition to the γ‐phase, one of the unannealed samples having relatively long hard and soft segments exhibits a high amount of α‐phase. This is assumed to be due to the high flexibility of the PEG segments, linking the polyamide blocks thus enhancing their mobility. The lack of hydrogen bonds between the PEG segments facilitates crystallization of the polyamide segments in the more perfect α‐modification, which is the most pronounced in the above mentioned sample. Part of the α‐phase transforms into the α‐phase upon annealing in all copolymer samples studied, similarly to polyamide‐6.
Low‐molecular‐weight poly(imide‐amide)s obtained by copolycondensation of 4,4′methylenedi(phenyl isocyanate), trimellitic acid anhydride and benzoic acid in N‐methyl‐2‐pyrrolidone, 1. The microstructure studied by 1H and 13C NMR
Authors: Sintès‐Zydowicz Nathalie , Pham Quang Tho , Michaud Philippe
Published: April 2003

Low‐molecular‐weight poly(imide‐amide)s (PIA) obtained by polycondensation at 180°C of 4,4′ ‐methylenedi(phenyl isocyanate), trimellitic acid anhydride and benzoic acid were studied by 1H and 13C NMR. Complementary 1H and 13C information was used to determine the distribution of II, IA, AA sequences and to show that the repartition of imide (I) and amide (A) groups along the chains is random. According to the composition of the monomer mixture, a slight deficiency of I is reproducibly observed. Non‐reacted benzoic acid is found, and unexpected traces of urea and amic acid groups are present in the PIA chains.
Synthesis of telechelics with furanyl end‐groups, 2 Radical polymerization with cc‐bond splitting initiators and network formation with unsaturated polyesters via diels‐alder additions
Authors: Edelmann Dirk , Ritter Helmut
Published: April 2003

New CC‐bond splitting initiators with two furanyl groups were prepared: 1,2‐di‐2‐furanyl‐1,2‐diphenyl‐1,2‐bis(trimethylsiloxy)ethane (4a), 1,2‐di‐2‐furanyl‐1, 2‐di‐p‐tolyl‐1, 2‐bis(trimethylsiloxy)ethane (4b) and 1,2‐di‐2‐furanyl‐1, 2‐dimesityl‐1,2‐bis(trimethylsiloxy)ethane (4c). Radical polymerizations of styrene and (meth)acrylates with the new CC‐bond splitting initiators were performed in solution at temperatures between 80–105°C. The telechelic oligomers were characterized by GPC and NMR spectroscopy, proving a furanyl functionality of two. The kinetics of the Diels‐Alder reactions between the furanyl‐terminated telechelics and dienophiles such as maleic anhydride and dimethyl maleate were measured under pseudo‐first‐order conditions. Addition of the telechelics to unsaturated polyesters prepared from maleic anhydride and diols led to a solid material with network structure.
Renewable resources, 1. Branching and crosslinking of an unsaturated oligoester with furfurylamides and sorbic acid amides via diels‐alder additions
Authors: Reinecke Martin , Ritter Helmut
Published: April 2003

The unsaturated polyester 1 prepared from maleic anhydride and 1,4:3,6‐dianhydro‐D‐glucitol was modified with the sorbic acid amides and furfurylamides 2, 3, 6, 7 and 8 via Diels‐Alder (DA) reactions. The cycloadditions with the monodienes 2 and 3, the bisdiene 6 and the trisdiene 7 led to branched derivatives, whereas the DA reaction with the tetradiene 8 yielded a crosslinked material. All compounds contain a high amount of molecules obtained from renewable resources.
Sulfur‐Containing polymers. New polythiocarbonates and polydithiocarbonate based on 4,4′‐isopropylidenedibenzenethiol
Authors: Bandiera Milena , Berti Corrado , Manaresi Piero , Marianucci Elisabetta , Pilati Francesco , Poloni Marino
Published: April 2003

New sulfur‐containing polycarbonates have been prepared by interfacial polycondensation of 4,4′‐isopropylidenedibenzenethiol with phosgene, bisphenol‐A bischloroformate and bisphenol‐A polycarbonate oligomers (OH/OCOCl terminated); high‐molecular‐weight polymers were obtained. The influence of the nature of the phase transfer catalyst on the yield and on the molecular weight of the polymers was studied. From thermogravimetry (TG) analysis it was possible to observe that the substitution of the oxygen atoms by sulfur atoms leads to less thermally stable polymers compared with the corresponding polycarbonate (bisphenol‐A polycarbonate).
Convenient synthesis of polymers containing terminal aldehyde and ketone moieties by selective oxidation of polymeric terminal diols with an oxoaminium salt
Authors: Yoshida Eri , Takata Toshikazu , Endo Takeshi
Published: April 2003

Synthesis of polymers with aldehyde or ketone groups at both chain ends was carried out by oxidation of polymeric terminal diols with an oxoaminium salt (OAS), the oxidized form of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl. Terminal diols of polyethers, polyesters, polycarbonates, polybutadiene, and hydrogenated polybutadiene were oxidized with 2,0 equiv. of OAS in dichloromethane at room temperature in the dark. The corresponding aldehyde‐and/or ketoneterminated polymers were obtained in high yields with high conversion of OH group and little change in molecular weight. Poly(ethylene glycol) and poly(ethylene adipate) terminal diols were oxidized with low efficiency. Especially, in the case of poly(ethylene glycol), intermolecular reactions occurred to afford high molecular weight polymer. The ratio of aldehyde (CHO) to ketone (CO) groups in the oxidized polymer originating from the hydrogenated polybutadiene terminal diol was calculated to be 37/63.
Group transfer polymerization of methyl methacrylate and butyl acrylate in tetrahydrofuran with oxy anions as catalysts
Authors: Schmalbrock Urban , Bandermann Friedhelm
Published: April 2003

Group transfer polymerization (GTP) of methyl methacrylate (MMA) and butyl acrylate (BA) in tetrahydrofuran with (1‐methoxy‐2‐methyl‐1‐propenyloxy)trimethylsilane (MTS) as initiator and tetrabutylammonium 3‐chlorobenzoate, tetrabutylammonium bi‐3‐chlorobenzoate and tetrabutylammonium bibenzoate as catalysts was investigated. It was found, that the reaction of MTS with all catalysts in the absence of monomers yields the same reaction products as common GTP catalysts. Furthermore, the time‐conversion curves of MMA and BA exhibit induction periods proving the assumption, that the first addition step of the monomer to the initiator is slower than the propagation reaction. With respect to molecular‐weight control, oxy anions are superior to tetrabutylammonium cyanide (TBACN) due to the missing capability of oxy anions to initiate an anionic polymerization, and bobenzoates are to be preferred to monobenzoates. It is discussed, that the reaction behaviour of oxy anions in GTP can also be understood on the basis of enolate anions as active polymerization species.
Polysiloxane‐Containing triblock copolymers via cationic ring‐opening polymerization of cyclic siloxanes
Authors: Mougin N. , Rempp P. , Gnanou Y.
Published: April 2003

A novel original method allowing the synthesis of polydimethylsiloxane (PDMS)‐containing triblock copolymers is described. The synthetical procedure is based on the use of ω‐silyl triflate‐terminated polymers serving as macroinitiators for cyclic siloxane polymerization. Due to the continous interchange reactions between the siloxane linkages and the reactive cationic sites, triblock copolymers are obtained. This method was applied to the synthesis of triblock copolymers with a central PDMS block and either two polystyrene or two poly(ε‐caprolactam) rigid external blocks. Another method, the well‐known “end‐blocker” technique, was unsuccessful for obtaining block copolymers.
Synthesis and characterization of processable aromatic poly(azomethine)s with ether linkages
Authors: Yeakel Craig , Gower Karmen , Mani Rajarathnam S.
Published: April 2003

High‐molecular‐weight polyketanils with flexible ether linkages were prepared by the reactions of N,N′‐bis[α(4‐fluorophenyl)benzylidene]‐1,4‐benzenediamine with phenoxides derived from several less acidic diphenols. Molecular sieves medicated reactions of 1,4‐benzenediamine with two equivalents of 4‐flurobenzophenone afforded the desired monomer in good yield. Formation of successive ether linkages via nucleophilic aromatic substitution reactions constituted the polymerforming step. The high‐molecular‐weight polymers form tough films upon compression molding, exhibit relatively high glass transition temperatures and good thermal stability.
Poly(ester‐imide)s derived from 3,4,9,10‐perylenetetracarboxylic acid, ω‐aminododecanoic acid and α,ω‐alkanediols
Authors: Karayannidis George , Stamelos Demetris , Bikiaris Demetris
Published: April 2003

A series of new poly(ester imide)s (PEI's, 6) was synthesized from 12, 12′‐(3,4: 9,10‐perylenetetracarboxdimido)didodecanoyl chloride (4) and various α,ω‐alkanediols (5). DSC measurements revealed for all PEI's a solid‐solid transition at ca. 190–200°C and a melting transition between 300–330°C. Neither a liquid‐crystalline phase not glass transition were detectable, suggesting the PEI's are highly crystalline. Heat distortion measurements showed that the crystallites form a coherent matrix and the amorphous phase is dispersed in the voids, which is quite different to other semicrystalline polymer. Decomposition started just above the melting and was completed at approx. 750–800°C.
Copolymers of substituted styrenes with vinylidene cyanide or methylvinylidene cyanide. 13C NMR studies of their microstructures
Authors: Monthéard Jean‐Pierre , Boinon Bernard , Belfkira Ahmed , Raihane Mustapha , Pham Q. T.
Published: April 2003

Various copolymers of vinylidene cyanide (1a) and methylvinylidene cyanide (1b) with substituted styrenes (2a–g) were synthesized by radical copolymerization, and their microstructures were studied by 13C NMR spectroscopy. The copolymers of vinylidene cyanide with substituted styrenes have a perfectly alternating structure, but the copolymers of methylvinylidene cyanide are rich in alternating structure and might contain a minor part of poly(substituted styrene) as blocks or as homopolymers. A distinction between the two possibilities was not possible.
Thermotropic liquid‐crystalline aromatic‐aliphatic polyimides, 2. Effect of aliphatic spacer lengths and polymer compositions on the liquid‐crystalline properties of poly(imide‐carbonate)s
Authors: Hirata Tomohiro , Sato Moriyuki , Mukaida Ken‐ichi
Published: April 2003

Novel thermotropic liquid‐crystalline (LC) aromatic‐aliphatic poly(imide‐carbonate)s were prepared by melt polycondensation of N,N′‐bis(ω‐hydroxyalkyl)pyromellitdiimide and/or 6,6′‐(4,4′‐biphenylylenedioxy)dihexanol with hexamethylene bis(phenylcarbonate). The monomers, dihydroxyalkyl derivatives of pyromellitdiimide, were obtained by deacetylation of the intermediate diacetylated compounds with p‐toluenesulfonic acid. The intermediates were synthesized by condensation of pyromellitic dianhydride (PMDA) with ω‐aminoalcohols followed by cyclization with acetic anhydride. Most of the poly(imide‐carbonate)s obtained in high yields have high molecular weights and show very good solubilities in organic solvents. The structures of the resulting polymers were confirmed by FT/IR and NMR spectroscopy measurements and elemental analyses. Thermotropic LC properties of the polymers were evaluated by differential scanning calorimetry (DSC), polarizing microscopy and powder X‐ray analyses. These measurements suggested that only biphenyl unit‐rich copolymers and polymers with shorter spacers next to the imide ring, which favor the orientation of the imide ring and the polymer chains, form nematic LC mesophases. The glass transition temperatures (Tg) and the LC phase transition temperatures tend to decrease with increasing imide‐neighboring aliphatic spacer lengths.
Static and dynamic light scattering studies of dextran from leuconostoc mesenteroides in the dilute region
Authors: Nordmeier Eckhard , Xing Hai , Lechner Manfred‐Dieter
Published: April 2003

Dextrans with mass‐average molar masses 8.104 g/mol ⩽ M̄w ⩽ 108 g/mol have been studied in water by means of static and dynamic light scattering at different temperatures. Static light scattering (SLS) yields the z‐average mean‐square radius of gyration, 〈S2〉z and the second virial coefficient A2. It is found that the dependences of 〈S2〉 and A2 on the mass‐average molar mass, M̄w, can be well described by the power laws 〈S2〉 = KS · M̄ and A2 = KA · M̄. The exponent vs is independent of the temperature T, while vA decreases as T is raised. Dynamic light scattering (DLS) yields the apparent diffusion coefficient, Dapp (q,c), and the hydrodynamic radius, Rh, where q is the wave vector and c the polymer concentration. For small q, a plot of Dapp (q, c) versus q2 · 〈S2〉z gives a straight line. The intercept $ D_{\rm z} (c) = \mathop {\lim }\limits_{q \to 0} D_{{\rm app}} (q,c) $ represents the centre‐of‐mass translational diffusion coefficient. Its dependence on the concentration, c, can be well simulated by the relation \documentclass{article}\pagestyle{empty}\begin{document}$ D_{\rm z} (c) = D_{{\rm z,}0} \left[ {1 + k_{{\rm D},2} \cdot c} \right] $\end{document}. Here kD, 2 is the second hydrodynamic virial coefficient and Dz,0 the z‐average of the translational diffusion coefficient at infinite dilution. The analysis of the kD,2 ‐data shows that dextran molecules behave rather as interpenetrable than as non‐interpenetrable spheres. The density p = (3 M̄w)/(NA · 4 π R) proves to be a measure for the degree of penetration; p decreases with increasing M̄w, indicating that penetration becomes easier at higher molar masses.