bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthèse d'un monomère styrénique à substituant phosphonique. Instabilité de la forme diacide et polymérisation
Authors: Boutevin Bernard , Hamoui Bachar , Bessière Jean‐marie M. 
Published: April 2003

Abstractp‐Vinylbenzyphonic acid was prepared by means of the Arbuzov reaction between triethyl phosphite and p‐chloromethylstyrene followed by silylation with bromotrimethylsilane and methanolysis. The product, which is readily cross‐linked, is stabilized as dicyclohexycylammonium salt. Radical‐initiated polymerization occurs readily; homo‐ and copolymers found are slowly cross‐linked upon releasing dicyclohexylamine.
Variation of the propagation rate coefficient with pressure and temperature in the free‐radical bulk polymerization of styrene
Authors: Buback Michael , Kuchta Frank‐Dieter 
Published: April 2003

AbstractThe propagation rate coefficient Kp of the free‐radical bulk polymerization of styrene is determined between 30 and 90°C up to a maximum pressure of 2800 bar. The data from pulsedlaser polymerizations and product analyses by gel‐permeation chromatography (PLP‐GPC) are adequately represented by the expression:

The conseaquences of deducing activation volumes and activation energies from kp/(L · mol−1 · s−1) or fromk*p/(kg · mol‐1 ·. S−1) are outlined.
1,3‐Oxazoline intermediates in reactive processing applications, 1. Melt grafting of poly(ethene‐co‐methacrylic acid) with 2‐substituted 1,3‐oxazolines
Authors: Müller Philipp , Wörner Christof , Mülhaupt Rolf 
Published: April 2003

AbstractA novel family of functional ethene copolymers with various side chains were prepared by melt grafting of poly(ethene‐co‐methacrylic acid), containing 3,00 and 4,25 mol‐% of methacrylic acid, with 2‐substituted 1,3‐oxazolines such as 2‐phenyl‐1,3‐oxazoline, 2‐undecyl‐1,3‐oxazoline, 2‐heptadecyl‐1,3‐oxazoline, and 4‐(1,3‐oxazolin‐2‐yl)phenyl 4‐methoxybenzoate. 1H NMR and FTIR studies of the polymer microstructures revealed that carboxylic acid groups reacted with 1,3‐oxazolines within few minutes to form esteramide‐coupled side chains in very high yields. Torque of the reaction mixture, mechanical and thermal properties of the graft copolymers were measured. In the case of 2‐heptadecyl‐esteramide‐substituted polyethenes, the side‐chain cocrystallization accounted for higher crystallinity of the resulting graft copolymers.
Synthesis and characterization of photosensitive 4,4′‐bis(dimethylamino)diphenylmethyl ethers of cellulose
Authors: Heinze Thomas , Erler Ulrich , Heinze Ute , Camacho Juan , Grummt Ulrich‐Walter , Klemm Dieter 
Published: April 2003

AbstractSoluble 4,4′‐bis(dimethylamino)diphenylmethyl ethers of cellulose (2) with a degree of substitution from 0,5 to 1,0 were prepared by therification of cellulose dissolved in N,N‐dimethylacetamide/LiCl. These ethers 2 show typical absorption spectra with an absorption maximum at 265 nm. While in neutral and basic medium 2 are stable, under acidic conditions a significant cleavage of the ether bonds occurs and thereby the formation of Michler's hydrol blue (absorption maximum at 604 nm). 2 was found to be photoconducting as film cast from a N,N‐dimethylformamide solution, for instance. Preliminary studies of the behavior of solutions of 2 by irradiation by means of flash photolysis and UV spectroscopy were carried out as well.
Electrochemically mediated polymerization of 2‐pentadecylaniline confined to a planar liquid‐liquid interface
Authors: Sigmund Wolfgang M. , Child Andrew D. , Reynolds John R. , Duran Randolph S. 
Published: April 2003

AbstractSpreading, isotherms and polymerization of 2‐pentadecylaniline at a planar aqueous electrolyte‐organic interface were examined by monitoring the interfacial pressure employing the Wilhelmy‐plate method. These results indicate the presence of monomer confined to the interface. Application of a voltage across the interface using stainless steel electrodes results in polymerization to form an electroactive polymer. The interfacial polymerization appears to be effected by metal ions formed by oxidation of the anode that have diffused into the aqueous electrolyte. This phenomenon is dependent on the nature of the electrode material as successful polymerization was not observed with other electrode materials. The polymer formed was soluble in polar organic liquids, was green in its reduced state and blue in its oxidized state, when oxidized and reduced chemically or electrochemically as a thin film. Cyclic voltammetry of the polymer indicates one reversible redox process suggesting that there are only two different oxidation states available, i.e., the equivalent to leucoemeraldine cannot be formed with poly(2‐pentadecylaniline) in a thin film. However, the fully reduced yellow leucoemeraldine can be formed in chloroform solution by hydrazine reduction.
Polymerization of methyl methacrylate with V(acac)3 and VOCl3 in combination with methylaluminoxane
Authors: Endo Kiyoshi , Inukai Akihiro , Otsu Takayuki 
Published: April 2003

AbstractThe polymerization of methyl methacrylate (MMA) with V(acac)3 and VOCl3 in combination with methylaluminoxane (MAO) was investigated. The obtained polymers have a relatively narrow molecular weight distribution (M̄w/M̄n < 1,5). It was found that the isotactic triad content of the polymers increases with increasing temperature and MAO/V and MAO/MMA mole ratios. The interaction between MMA and MAO has an influence on the tacticity of radically (initiator AIBN) obtained polymers: in presence of MAO the fraction of isotactic triads (mm) is higher. The catalytic activity of MAO‐containing catalysts (V(acac)3/MAO and VOCl3/MAO) was compared with that of AlEt3‐containing catalysts (V(acac)3/AlEt3 and VOCl3/AlEt3). It was not much different, but for MAO as cocatalyst the isotacticity of the resulting PMMA's was higher, and the polydispersity lower, than with AlEt3 as cocatalyst.
Binary blends of poly(ethylene terephthalate) with thermotropic liquid‐crystalline copolyesteres: Thermal, morphological and mechanical studies
Authors: El‐Amouri Issam , Skoulios Antoine , Quentin Jean‐Pierre 
Published: April 2003

AbstractBinary mixtures of a thermoplastic engineering poly(ethylene terephthalate) (PETP) with a thermotropic liquid‐crystalline random copolyester (PCL) were prepared by melt blending the polymers in a screw extruder or by precipitating them from a solution in a common solvent. Differential scanning calorimetry and polarizing optical microscopy were used to study their thermal and morphological properties as a function of temperature and composition. At high temperature, the blends rich in PETP are isotropic liquids, those rich in PCL are nematic fluids, and those of intermediate compositions are formed of two phases in equilibrium, one liquid‐isotropic and one nematic. At low temperature, the blends are generally biphasic, with the two component polymers crystallized. The presence of crystallized PCL proved not to act as a nucleating agent towards the crystallization of PETP from the melt. A schematic phase diagram was drawn to summarize the thermal and morphological behaviour of the blends. Scanning electron microscopy studies of injection moulded samples revealed the presence of highly oriented fibrils when the composition exceeded roughly 50 wt.‐% in PCL. The bending elastic modulus of the injected blends with 75 wt.‐% of PCL surpasses that of the pure PCL, probably due to the presence of oriented high‐molecular‐weight PETP molecules. The particular dependence of the mechanical rigidity upon the concentration of PCL permits easily to determine conditions for the thermoforming of PETP.
On the time‐concentration superposition of the linear viscoelastic properties of plasticized polystyrene melts using the free volume concept
Authors: Schausberger Alois , Ahrer Iris V. 
Published: April 2003

AbstractPlasticizing agents are known to shift the material functions of polymer melts like raised temperatures to shorter times and to higher frequencies. The influence of dioctyl sebacate, dioctyl phthalate and bibenzyl on the viscoelastic properties of polystyrene melts is sized by shift factors which can be evaluated very exactly from the dynamic moduli in the rubber‐like liquid region. Besides, these shift possibilities enable us to enlarge the experimental window to the low frequency region for some decades. The typical diluent effect caused by the additives is quite similar to the one caused by not entangled polymer molecules. The lowering of the plateau modulus, i. e., the shift on the modul axis, is found to be equal to the square of the weight fraction of the polymer. The reduction of the relaxation times, i. e., the shift on the time or frequency axis, mainly is due to the increased fraction of free volume accounted for by A/Mn,c, where A rates the fraction created by one mole additive and A/Mn,c is the number‐average of the molar masses of polymer and additive. The influence of the free volume on the relaxation times is calculated with the aid of a Doolittle equation. The Concentration dependence of the time‐temperature shift factors is also accounted for by A/Mn,c. Therefore, besides the parameter A, only the three parameters used in (and known by) the analysis of the time‐temperature superposition principle, i. e., the fraction of free volume of the pure polymer (f), the thermal expansion coefficient of f (αf) and the Doolittle parameter B, are needed for the calculation of the temperature‐dependent time‐concentration shift factors and of the concentration‐dependent time‐temperature shift factors as well.
Use of fluorescence to study inverse microemulsion polymerization of acrylamide
Authors: Lacík Igor , Bartoň Jaroslav , Warr Gregory G. 
Published: April 2003

AbstractSteady‐state fluorescence was used to study the polymerization of acrylamide (AAM) in inverse microemulsions comprising water/bis(2‐(ethylhexyl)sodium) sulfosuccinate (AOT)/toluene in order to investigate the AAM depletion from various loci of microemulsion in the process of polymerization. AAM has the role of both reactive monomer and consurfactant in this microemulsion, and also acts as a quencher for the indole fluorescent probes: 1,2‐dimethylindole, indole and L‐tryptophan. These were selectively placed within various loci of the microemulsion (toluene, interphase and water phase), enabling us to follow the depletion of AAM by monitoring the fluorescence of each probe during polymerization. The obtained results show a monotonic decrease of the AAM concentration regardless of the probe localization in the microemulsion polymerization system.
Characterization of DEAE‐dextran by means of light scattering and combined size‐exclusion chromatography/low‐angle laser light scattering/viscometry
Authors: Hanselmann Ralf , Burchard Walther , Lemmes Rolf , Schwengers Dieter 
Published: April 2003

AbstractTen DEAE (2‐(diethylamino)ethyl) dextran samples were investigated by means of static and dynamic light scattering, viscometry and size‐exclusion chromatography (SEC) in combination with on‐line small‐angle laser light scattering (LALLS) and viscometry (VISC). In dilute solution the behavior of DEAE‐dextran was compared with that of unsubstituted dextran and the molecular weight M dependences of the radius of gyration Rg, hydrodynamic radius Rh, intrinsic viscosity [η], second virial coefficient A2 and z‐average diffusion coefficient Dz were determined. The relationships for DEAE‐dextran dissolved in a 0,8 molar sodium nitrate solution were nearly the same as for dextran dissolved in water with 0,05 wt.‐% sodium azide and gave the same exponents. The molecular weight dependence of the intrinsic viscosity cannot be described by a Kuhn‐Mark‐Houwink relationship with a constant exponent. The slope in the plot of log [η] versus log M decreases with increasing molecular weight which indicates the occurrence of branching. By means of SEC/LALLS/VISC measurements the molecular weight distributions were determined. The distributions were calculated (1) directly from the light scattering signal, (2) from a calibration line obtained by light scattering data of a DEAE‐dextran sample with a broad distribution and (3) from the intrinsic viscosity distribution obtained by the on‐line viscosity/refractive index detector in combination with the [η]‐M relationship. In order to get the correct molecular‐weight dependence of the intrinsic viscosity it is necessary to determine the molecular weight distribution directly by LALLS (technique 1) and to combine this with the appropriate intrinsic viscosity data from the viscometer. Only the third technique, which is an extension of technique 1, gave satisfactory results over the whole molecular weight region observed.
Functionalized initiators for group transfer and metal‐free anionic polymerization for the synthesis of macromonomers: overview and new results
Authors: Bandermann Friedhelm , Beckelmann Dirk , Broska Dirk , Fieberg Andreas , Roloff Thorsten , Wolters Dieter 
Published: April 2003

AbstractVinylphenyloxy‐ and allyloxy‐substituted silyl ketene acetals are presented as new functionalized initiators for group transfer polymerization (GTP). All initiators initiated GTP of butyl acrylate in tetrahydrofuran with tetrabutylammonium cyanide as catalyst to yield butyl acrylate macromonomers with number‐average molecular weights somewhat lower than those calculated for an ideal living polymerization and with polydispersities of about 1,8–2,6. For the metal‐free anionic polymerization, functionalized initiators were obtained introducing allyloxy and vinylbenzyl groups into tetrabutylammonium diethyl malonate. Both compounds initiated a very rapid polymerization of butyl acrylate in tetrahydrofuran with high monomer conversion. The number‐average molecular weights of the macromonomers, produced in a semi‐batch procedure, reached nearly theoretical values, the polydispersities were about 1,2. In all macromonomers the functionality with respect to terminal vinyl and allyl groups was near one, so that they can be used with other monomers to form graft copolymers, e. g., in a free‐radical polymerization.
Study of 1,4‐bis(propylaminomalonylamino)butane as a model compound for nylons n,3
Authors: Navarro Eloísa , Puiggalí Jordi , Subirana Juan A. 
Published: April 2003

AbstractWe are presently studying n,3 nylons, which have an unusual hydrogen bonding system. In order to determine their structure with greater precision, we have synthesized and determined by X‐ray diffraction the structure of a dimer of the repeating unit of nylon 4,3, namely, 1,4‐bis(propylaminomalonylamino)butane (pMBMp). This compound crystallizes in the triclinic system, space group P1 with a = 4,65, b = 4,91, c = 24,47 Å; α = 85,3, β = 89,7 and γ = 61,9°. The malonyl residues of pMBMp are related by an inversion center, with torsional angles about the methylene bonds of each malonyl residue in the range 110–115° (or the equivalent negative values). A. conformation TS̄(T)3ST was found for the butylenediamide unit. These results give support to the crystalline structure proposed for nylons n,3.
A novel synthesis and characterization of phenylacetylene end‐capped poly(aryl ether sulfone) and poly(aryl ether ketone) oligomers
Authors: Kozuch Mathew , Schaffer Angela , Bhatnagar Atul , Phulpagar Stanley , Mohanty Dillip K. 
Published: April 2003

AbstractA series of controlled molecular weight poly(aryl ether sulfone) oligomers with benzophenone moieties at the chain termini were prepared. The two carbonyl groups at the chain ends were converted to ethynyl groups by using trimethylsilyldiazomethane/BuLi in tetrahydrofuran. Reactions of 4,4′‐isopropylidenediphenol with 4,4′‐difluorobenzophenone and 4‐fluorophenylphenylacetylene as the end‐capping reagent in N,N‐dimelthylacetamide afforded the desired poly(aryl ether ketone) oligomers Both sulfone and ketone containing oligomeric polyethers undergo crosslinking reactions at elevated temperatures.
Allyl reactivity in group transfer copolymerization
Authors: Öncül‐Koç Ayşegül , Catalgil‐Giz Huceste 
Published: April 2003

AbstractStatistical copolymers of allyl methacrylates with methyl and ethyl methacrylates are synthesized. Moderate conversions are used. Reactivity ratios are calculated by linearised methods which take composition drift into account as well as by non‐linear least‐squares approximation. For the allyl methacrylate/methyl methacrylate system, rallyl values obtained by various methods are between 1,62 and 1,60 and rmethyl values between 0,36 and 0,34. For the allyl methacrylate/ethyl methacrylate system, rallyl values are between 1,37 and 1,16 and rethyl values between 0,40 and 0,47.
Synthesis and characterization of novel side‐chain liquid crystalline polycarbonates, 2. Polycondensation of mesogenic diols and diphosgene
Authors: Jansen John , den Ridder Patrick , Addink Rudolf , Mijs Wim 
Published: April 2003

AbstractA series of new side‐chain liquid crystalline polymers was prepared with a polycarbonate backbone, bearing (E)‐4′‐nitrostilbene mesogenic groups, connected to the backbone by spacers of different length. The polymers were synthesized in 1,4‐dioxane by polycondensation of diphosgene and diol monomers with the general structure 2‐[ω‐(4′‐nitrostilben‐4‐ylcxy)alkyloxy]‐1,3‐propanediol in the presence of pyridine as a proton trap and catalyst. The mesomorphic properties of all monomers, polymers and intermediates were studied by polarized optical microscopy and differential scanning calorimetry (DSC). The polymers were also studied by X‐ray diffraction of non‐oriented and oriented samples (fibres). All monomers were liquid crystalline with nematic and/or smectic phases. For the polymers a clear relation was found between spacer length and glass transition temperature (Tg), which decreases with increasing spacer length and between spacer length and clearing temperature, which increases with increasing spacer length. X‐ray diffraction measurements indicated the presence of a smectic A double layer structure (SAd) for all polymers at room temperature, with an antiparallel of overlapping mesogenic groups. A distinct difference in the orientation of the mesogens was found when fibres were drawn from the smectic phase or from the nematic or isotropic phase. In the first case the mesogenic groups were oriented perpendicular to the fibre axis and in the second case the mesogenic groups were oriented parallel to the fibre axis. By gel‐permeation chromatography (GPC) measurements of heated samples and by thermogravimetric analysis (TGA) and DSC the polymers were found to be thermally stable up to temperatures well above their clearing point.
NMR study of miscibility and morphology of polyimide/polyimide blends
Authors: Feng Hanqiao , Ye Chaochui , Zhang Ping , Sun Zhenhua , Feng Zhiliu 
Published: April 2003

AbstractThe miscibility and morphology of polyimide/polyimide blends, PEI‐E/PTI‐EPEI‐E: poly(ether imide‐ether), PTI‐E: poly(thioetherimide‐ether), PBPI‐E: poly(biphthalimide‐ether); cf. exptl. part.
and PBPI‐E/PTI‐E, have been studied by means of 13C CPMAS NMR technique. The results indicate that PEI‐E/PTI‐E blends are miscible on a molecular level, but molecular aggregation exists in pure PBPI‐E specimen as well as PBPI‐E/PTI‐E blends with high content of PBPI‐E, which vanishes in the blends with high content of PTI‐E. When the content of PBPI‐E is higher than that of PTI‐E, the addition of PTI‐E to PBPI‐E has almost no effect on the size of the PBPI‐E rigid domains, but has a large effect on the populations of the PBPI‐E rigid domains. It is the intermolecular charge‐transfer interaction that plays a critical role in the miscibility of PEI‐E/PTI‐E and PBPI‐E/PTI‐E blends.
Preparation, properties and complex formation ability of poly(ether‐ester)s of poly(ethylene glycol)s and 2,6‐pyridinedicarboxylic acid
Authors: Ignatova Milena , Manolova Nevena , Rashkov Iliya , Sepulchre Maurice , Spassky Nicolas 
Published: April 2003

AbstractPoly(ether‐ester)s of poly(ethylene glycol)s (PEGs) and 2,6‐pyridinedicarboxylic acid (PDA) were synthesized by polycondensation of PDA and PEG in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine and by polycondensation of acyl chloride of PDA and PEG in the presence of triethylamine at 45°C. The polymers were characterized by GPC, UV, IR and 1H and 13C NMR spectroscopy. The complex formation between poly(acrylic acid) (PAA) or poly(methacrylic acid) (PMA) and the poly(ether‐ester)s was studied. It occurs below the critical polyether chain length necessary for complex formation because of the stabilizing effect of the PDA hydrophobic residues.
Optically active polymers bearing side‐chain photochromic moieties: synthesis and chiroptical properties of methacrylic and acrylic homopolymers with pendant L‐lactic acid or L‐alanine residues connected to trans‐4‐aminoazobenzene
Authors: Angiolini Luigi , Caretti Daniele , Carlini Carlo , Salatelli Elisabetta 
Published: April 2003

AbstractNovel optically active monomers such as trans‐(S)‐4‐(2‐methacryloylaminopropano‐ylamino)azobenzene, trans‐(S)‐4‐(2‐methacryloyloxypropanoylamino)azobenzene, and trans‐(S)‐4‐(2‐acryloylaminopropanoylamino)azobenzene have been prepared and homopolymerized by free radical initiation. Circular dichroism spectra of the resulting polymeric systems, as compared with those obtained for the corresponding low molecular weight analogues, purposely synthesized, allow one to suggest that the macromolecules assume in solution conformations with different homogeneity and prevailing chirality, depending on their structural requirements and solvent interactions.
Synthesis and characterization of isotactic cis‐1,4‐poly(3‐methyl‐1,3‐pentadiene)
Authors: Ricci Giovanni , Zetta Lucia , Porri Lido , Meille Stefano Valdo 
Published: April 2003

Abstract3‐Methyl‐1,3‐pentadiene has been polymerized with the Al(C2H5)2Cl/Nd(OCOC7H15)3/Al[CH2CH(CH3)2]3 system to crystalline polymers consisting essentially of cis‐1,4 units (≥80%). NMR examination has shown that the polymers have an isotactic structure. This conclusion was confirmed by X‐ray analyses, which further indicated that cis‐1,4 isotactic poly(3‐methyl‐1,3‐pentadiene) exists in polymorphic modifications.
Structural changes induced by thermal treatments on emptied and filled clathrates of syndiotactic polystyrene
Authors: Manfredi Carla , De Rosa Claudio , Guerra Gaetano , Rapacciuolo Mariateresa , Auriemma Finizia , Corradini Paolo 
Published: April 2003

AbstractThe solvent molecules included in the clathrates (δ‐form) of syndiotactic polystyrene (s‐PS) are removed by suitable extraction procedures. An emptied δ‐form is produced which is different from the known γ‐form obtained by heating. The structural changes induced by thermal treatments on emptied and filled clathrates of s‐PS, have been followed by thermogravimetry, X‐ray diffraction analysis, differential scanning calorimetry and Fourier‐transform infrared spectroscopy. It is shown that, under suitable conditions, the emptied clathrates can be transformed into a mesomorphic form, which retains the chains in the helical conformation. This “helical” mesomorphic form, different from the previously known “planar” mesomorphic form, crystallizes by thermal treatments into the “helical” crystalline γ‐form.
Equation‐of‐state parameters of poly(vinyl acetate) as function of molecular weight
Authors: Casarino P. , Brunacci A. , Pedemonte E. 
Published: April 2003

AbstractSpecific volume, thermal expansion coefficient and thermal pressure coefficient are measured for poly(vinyl acetate) of different molecular weights. From these data the Flory equation‐of‐state characteristic parameters v*, T* and p* are determined. Comments on theoretical expectations and experimental behaviour are made.