bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of cloud‐point, shadow and other coexistence curves in multicomponent systems from measurements of phase volume ratios
Authors: Borchard Werner , Frahn Stephanie , Fischer Volker
Published: April 2003

Liquid‐liquid demixing of polydisperse polymer systems is described by volume balance equations relating the phase volume ratio to the bulk concentration of a polymer and its equilibrium concentrations. It is shown that in a system of a solvent and a polydisperse polymer, cloud‐point and shadow curves and the concentrations of coexisting phases may be obtained from the linearized volume or mass conservation equation. Also half meter curves for different phase volume ratios are obtained. The intersection of the half meter curve for equal phase volumina of coexisting phases with the cloud‐point or shadow curve leads to a determination of the critical point. The findings are illustrated in the system poly(ethylene oxide)/water, where the thresholds of cloud‐point and shadow curves do not coincide with the critical demixing point. This is typical of a multicomponent polymer/solvent system.
Intramolecular energy transfer in bichromophoric diesters containing anthracene and naphthalene groups separated by different numbers of methylene spacers
Authors: Bravo Julio , Mendicuti Francisco , Saiz Enrique , Mattice Wayne L.
Published: April 2003

Steady state fluorescence has been used to study the efficiency of nonradiative singlet energy transfer from naphthalene to anthracene in naph‐COO(CH2)mOOC‐anth for m of 2–6. A theoretical analysis has also been performed, using the rotational isomeric state model, of the conformations of these molecules. The experiments clearly demonstrate the presence of nonradiative singlet energy transfer in the bichromophoric compounds, with an efficiency that depends on the solvent and on m. The combination of the experiments and the theoretical analysis establishes that the Förster radius for this system is 1,6 ± 0,2 nm.
Synthesis and properties of aromatic telechelic monodisperse diols, 1. Radical‐initiated addition of 10‐undecen‐1‐ol to new aromatic α,ω‐dithiols
Authors: Améduri Bruno , Boutevin Bernard , Khamlichi Mohammed , Robin Jean‐Jacques , El Idrissi Abderrahman , Ramdani Abdelkarim
Published: April 2003

The synthesis of aromatic telechelic monodisperse diols produced from the radical‐initiated addition reaction of a two‐fold excess of 10‐undecen‐1‐ol and new α,ω‐dithiols is presented. The dithiols were prepared by esterification of thioglycolic acid with monodisperse telechelic diols obtained by fractionation of oligo(ethylene terephthalate)s and oligo(tetramethylene terephthalate)s. In all the cases, the long‐chain α,ω‐diols were produced selectively and quantitatively. The diols are soluble in most organic solvents, contrary to classical oligo(ethylene terephthalate)s and oligo(tetramethylene terephthalate)s.
End‐group analysis of poly(phenyl glycidyl ether), 1. Hydroxylic groups using 1H and 13C nuclear magnetic resonance
Authors: Ronda Joan Carles , Serra Angels , Mantecón Ana , Cádiz Virginia
Published: April 2003

The hydroxylic end‐groups in the soluble fraction of poly(phenyl glycidyl ether) (PPGE) obtained with the aluminium isopropoxide (AIP)/ZnCl2 initiator system are studied using nuclear magnetic resonance spectroscopy (NMR). To achieve complete assignment, model compounds are synthesized and their carbamate and trifluoroacetate derivatives obtained from trichloroacetyl isocyanate (TAI) and trifluoroacetic anhydride (TFAA) are prepared. These derivatizating reagents allow primary and secondary alcohols to be distinguished, since upfield or downfield shifts are produced, and at the same time they have the potential of separating overlapping peaks. Several PPGEs with different degrees of regularity are also synthesized using various initiator systems. Thus, it is possible to identify the carbon signals of both final hydroxylic groups and their adjacent units, and the presence of two types of unit linked to secondary hydroxylic end‐groups is demonstrated. Likewise, in the soluble fraction prepared with AIP/ZnCl2 the absence of the irregular units linked to secondary hydroxylic end‐group is demonstrated, so proving the high regularity of this fraction.
End‐group analysis of poly(phenyl glycidyl ether), 2. Hydroxylic groups using 19F nuclear magnetic resonance
Authors: Ronda Joan Carles , Serra Angels , Mantecón Ana , Cádiz Virginia
Published: April 2003

The hydroxylic end‐groups in the soluble fraction of poly(phenyl glycidyl ether) (PPGE) obtained with the aluminium isopropoxide (AIP)/ZnCl2 initiator system are studied using 19F NMR spectroscopy. Derivatization as trifluoroacetate esters affords poor structural information and handle difficulties. Hexafluoroacetone (HFA) hemiketalic adducts are much more easily prepared and offer more information, allowing not only to distinguish between primary and secondary alcohols but showing a clear sensitivity to the tacticity. This method is successful to calculate the percentage of hydroxylic end‐group in the polymer chain. In the case of an irregular PPGE sample, obtained with AIP alone as initiator, it is possible to identify three different hydroxylic end‐groups.
Synthesis and molecular weight characterization of low molecular weight end‐functionalized poly(4‐acryloylmorpholine)
Authors: Ranucci Elisabetta , Spagnoli Gloria , Sartore Luciana , Ferruti Paolo , Caliceti Paolo , Schiavon Oddone , Veronese Francesco M.
Published: April 2003

New amphiphilic oligomers ending at one side with a reactive function were synthesized by radical polymerization of a vinyl monomer,N‐acryloylmorpholine, in the presence of functionalized chain‐transfer agents (CTAs). The oligomers were characterized in terms of molecular weight and molecular weight distribution, by means of analytical size‐exclusion chromatography (SEC) working in buffered aqueous media. This has been accomplished by determining a calibration curve for a set of SEC columns, with poly(N‐acryloylmorpholine) standards purposely obtained by means of preparative SEC. The transfer constantCTof some CTAs towardsN‐acryloylmorpholine has been estimated to be approximately 1.
Thermostable block copolymers, 1. Thermotropic poly(ester‐imide) block copolymers
Authors: Eck Thomas , Gruber Heinrich F.
Published: April 2003

New poly(ester‐imide) block copolymers were prepared by polycondensation of aminoterminated poly(ester‐imide) blocks with molecular weights from 700 to 6 000 with terephthaloyl dichloride, isophthaloyl dichloride, 2,6‐naphthalenedicarbonyl dichloride, adipoly dichloride, dichlorodimethylsilane or dichlorotetramethylsiloxane as low‐molecular‐weight difunctional coupling reagents. The poly(ester‐imide) blocks were synthesized from readily accessible monomers. Dependent on block composition, molecular weight of the block (block length) and kind of spacer liquid‐crystalline polymers were obtained with high thermal stability and solubility in polar solvents, yielding tough films with good mechanical properties. The formation of thermotropic mesophases required the proper balance between the rigid blocks and the flexible, kinked or “crankshaft” spacers.
Protein adsorption on a copolymer having pendant monosaccharide groups. Relationship between surface free energy and protein adsorption
Authors: Miyata Takashi , Ootsuki Norihito , Nakamae Katsuhiko , Okumura Masakazu , Kinomura Keisuke
Published: April 2003

Protein adsorption on copolymer films having pendant monosaccharide groups was investigated from the viewpoint of surface chemistry. The copolymers were synthesized by the copolymerization of a monomer having a pendant monosaccharide (GEMA) and methyl methacrylate (MMA). The contact angles of methylene iodide and air bubble on the GEMA‐MMA copolymer films were measured in water, and the surface free energy of the copolymer films in water was calculated from the contact angles. With increasing GEMA content, the amount of protein adsorbed on the GEMA‐MMA copolymer films decreased gradually. The relationship between protein adsorption and the surface free energy of the copolymer films in water is discussed. The differences between surface free energy before and after protein adsorption on the copolymer surface is closely related to the amount of adsorbed protein.
Effect of solvent evaporation rate on microphase‐separated structure of segmented poly(urethane‐urea) prepared by solution casting
Authors: Ikeda Yuko , Tabuchi Masato , Sekiguchi Yasuhiro , Miyake Yoshikazu , Kohjiya Shinzo
Published: April 2003

A useful instrument for polymer film preparation by solution casting was employed in this study. It enabled us to control the solvent evaporation rate of the polymer solution. By using this instrument, the aggregation of hard segments in segmented poly(urethane‐urea) (SPUU) was investigated. SPUU was prepared from poly(tetramethy1ene oxide), 4,4′‐diphenylmethane diisocyanate and ethylenediamine. The effect of solvent evaporation rate on the microphase‐separated structure of SPUU was elucidated by dynamic mechanical analysis, tensile test, differential scanning calorimetry analysis, small‐angle X‐ray scattering measurement, IR and IR dichroism analyses. The aggregation of hard segments in SPUU was observed to be affected considerably by the solvent evaporation rate of the cast film during the preparation. It was found that the slower the solvent evaporation rate, the higher the aggregation of hard segments to form rigid hard segment domains in SPUU. Nine months after casting, this casting effect still remained on the aggregation state of hard segments of SPUU films, although the interdomain spacing was not influenced by its rate.
Semiflexible main‐chain liquid crystal polymers — the influence of the chemical structure on liquid crystalline properties
Authors: Pörschke Ralf , Höcker Hartwig
Published: April 2003

Two new homologous series of semiflexible main‐chain polyesters on the basis of 4‐hydroxy‐and 4‐carboxycinnamic acid in conjugation with 2‐tert‐butylhydroquinone and alkylene spacers with 3 to 8 methylene groups were prepared by low‐temperature solution condensation. The thermotropic properties were investigated by means of differential scanning calorimetry, polarising microscopy and X‐ray diffraction analysis. The differences in enantiotropic behaviour and thermal stability of the mesophases influenced by the two different linkage groups between alkylene spacer and rigid moiety are discussed in comparison to related systems known from the literature.
Ring‐opening‐closing alternating copolymerization of 2‐methyl‐2‐oxazoline with N‐methyldiacrylamide
Authors: Kadokawa Jun‐ichi , Matsumura Yoshitaka , Kobayashi Shiro
Published: April 2003

This paper describes a new ring‐opening‐closing alternating copolymerization (ROCAC) of 2‐methyl‐2‐oxazoline (five‐membered cyclic imino ether, 1) with N‐methyldiacrylamide (2). The reaction of a 1 : 1 monomer feed ratio proceeded without any added catalyst to give an alternating copolymer 3 having two structural units formed by ring‐opening and ring‐closing (cyclization). The structure of copolymer 3 was determined by 1H, 13C NMR, and IR spectroscopies. The extent of cyclization was at most 65%. The copolymerization was reasonably explained by a mechanism of propagation via zwitterion intermediates.
Biosynthesis of polyesters from some unusual amino acids having linear carbon skeleton by Alcaligenes eutrophus
Authors: Inoue Yoshio , Fujita Masayuku , Ohta Osamu , Nakamura Kazuhiro , Kuroki Hiroko , Yoshie Naoko
Published: April 2003

The biosynthesis of polyesters by Alcaligenes eutrophus from some unusual amino acids having a linear carbon skeleton was investigated. Poly(3‐hydroxybutyrate) (P(3 HB)) or poly(3‐hydroxy‐butyrate‐co‐3‐hydroxyvalerate) (P(3HB‐co‐3HV)) was found to be accumulated in the cells when a‐amino acids with a linear carbon skeleton were used as the sole carbon source. The 3HV mole fractions in copolyesters ranged up to 70%. The following pathway is proposed; the a‐amino acid with a linear carbon skeleton is at first metabolized to form the a‐keto acid by oxidative deamination with transaminase. Then the resulted a‐keto acid is converted into acyl‐CoA by oxidative decarboxylation, and the acyl‐CoA is further metabolized to the 3HB or 3HV unit through the same pathway as the fatty acids. P(3HB) was found to be produced from a‐amino acids having a linear skeleton with odd carbon number, whereas P(3HB‐co‐3HV) arises from a‐amino acids having a linear skeleton with even carbon number. This regularity is inverse to that of fatty acids, because amino acids are decarboxylated, with a reduction of one carbon atom, and then enter into the same synthetic pathway as fatty acids to form polyesters. On the other hand, when ω‐amino acids with a linear carbon skeleton were used as the sole carbon source, accumulation of polyesters was scarcely detected.
Langmuir‐blodgett films of photochromic polyglutamates, 7. The photomechanical effect in monolayers of polyglutamates with azobenzene moieties in the side chains
Authors: Menzel Henning
Published: April 2003

Monolayers of the photochromic hairy‐rod type polymers poly(5‐[2‐[4‐(4‐hexylphenylazo)‐phenoxy]ethyl]‐L‐glutamate) (1) and poly(5‐(2‐[4‐(4‐decyloxyphenylazo)phenoxy]ethyl)‐L‐glutamate) (2) were investigated at the air/water interface. At constant surface pressure the monolayers of the polymers exhibit a reversible expansion upon irradiation with ultraviolet (UV)‐light, due to the photoinduced E‐Z‐isomerization of the azobenzene chromophore and a concomitant restructuring of the monolayer. The area increase is lower than expected from the isotherms of monolayers spread from irradiated and non‐irradiated solutions. This can be attributed to a hindrance of photoisomerization, as proved by UV/Vis spectroscopic investigations. The hindrance of photoisomerization, and the photomechanical effect depend on temperature, surface pressure and the nature of the polymer, which all influence the flexibility of the monolayer. From a comparison of the isomerization rate and the rate of the photomechanical effect a two‐step mechanism for the monolayer restructuring is deduced.
In situ poling and polymerization of multifunctional monomers for second harmonic generation
Authors: Kasic James F. , Kannurpatti Anandkumar R. , Bowman Christopher N.
Published: April 2003

A novel method for the synthesis of second harmonic generating (SHG) materials is proposed and tested in which liquid, multifunctional monomers with dissolved dopants are poled and polymerized simultaneously. Instead of requiring multiple steps and hours or days to synthesize SHG materials, this technique is able to produce doped guest/host systems in a single step process which takes two minutes or less. In addition, the polymer that is produced is highly crosslinked and provides good thermal and temporal stability of the SHG. To increase the stability of the SHG signal the dopant can be attached to the crosslinked network further decreasing the mobility. Advantages of this process include its simplicity, speed, stability, and the ability to make SHG materials of any thickness by successively polymerizing layers. This work presents a detailed description of the new procedure as well as results for the effect of dopant concentration, the magnitude of the SHG, and the structure of the crosslinked polymer that serves as the dopant host. Also, a method of synthesizing functionalized Disperse Red 1 that can be incorporated as a side chain is presented. Results are presented for the order parameter and SHG stability at room temperature and 100°C.
Poly(vinyl alcohol) functionalized by chloroacetate groups. Coupling of bioactive carboxylic acids
Authors: Arranz Felix , Bejarano Eva María , Sanchez‐Chaves Manuel
Published: April 2003

Poly(vinyl alcohol) (PVAL) functionalized with chloroacetate groups was obtained by reaction of PVAL with chloroacetyl chloride using pyridine as catalyst and N‐methyl‐2‐pyrrolidone as solvent. The structure of the modified polymers was determined by means of IR, 1H and 13C NMR spectroscopies. The coupling of model bioactive carboxylic acids (1‐naphthylacetic acid and 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (naproxen)) to PVAL functionalized with chloroacetate groups was carried out by reaction with their potassium salts or directly in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU). High degrees of modification were obtained in the reaction with the potassium salts. However, the esterification reaction is somewhat more efficient in the case of the potassium salt of 1‐naphthylacetic acid. The kinetic results were consistent with a second‐order reaction, and the activation energy in the reaction with the potassium salt of 1‐naphthylacetic acid was found to be 73,2 kJ/mol. The reaction of PVAL with 1‐naphthylacetic acid and naproxen in the presence of DBU showed deviation from second‐order kinetics, which may be a consequence of some steric effects. The hydrolysis in the heterogeneous phase of PVAL‐1‐naphthylacetic acid and PVAL‐naproxen adducts showed that the release of the bioactive compound from tablets is dependent on the hydrophilic character of the adduct as well as on the pH value of the medium.
Synthesis of side‐chain liquid‐crystalline polysalts with a poly(methylsiloxane) backbone
Authors: Ikker Andreas , Frère Yves , Masson Patrick , Gramain Philippe
Published: April 2003

The synthesis and thermal properties of side‐chain liquid‐crystalline polysiloxanes, incorporating quaternized pyridyl groups, are described. The polymers are obtained by hydrosilylation of poly(hydrogenmethylsiloxane) with a protected alcohol. Reaction of the deprotected polysiloxanes with 4‐(hydroxymethyl)pyridine and subsequent reaction with mesogenic alkyl bromides of different structure yielded the desired poly[(6‐{N‐[ω‐(4′‐alkoxy‐4‐biphenylyloxy)alkyl]‐4‐pyridiniomethoxy}hexyl)methylsiloxane bromide]. Four different types of polymers are prepared with either octyl or dodecyl alkyl chain, and with either methoxy or S‐2‐methyl‐1‐butoxy as an alkoxy group. Degrees of quaternization up to 80% are obtained. First results of their liquid‐crystalline behaviour investigated by optical polarizing microscopy and differential scanning calorimetry are reported.
Solvent‐induced ion selective transport properties of a crosslinked poly(L‐glutamic acid) membrane
Authors: Huh Yang‐Il , Kai Shojiro , Satoh Mitsuru , Komiyama Jiro
Published: April 2003

Ion‐selective transport of alkali metal chlorides (LiCl, NaCl, KCl and CsCl) is reported for a crosslinked poly(L‐glutamic acid) membrane immersed in aqueous alcohols CH3OH, C2H5OH and 2‐propanol ((CH3)2CHOH). In aqueous CH3OH and C2H5OH, an appreciable ionselectivity was observed for the permeability coefficient, i.e., Li+ < Na+ < Cs+ ≤ K+, in a higher alcohol composition region. This counterion sequence results from a significant increase in the salt solubility coefficient of KCl and CsCl and a substantial decrease in the diffusion coefficient of LiCl and NaCl in the relevant alcohol composition region. Membrane conductivity measurements, which were performed concomitantly for the aq. C2H5OH system, suggest the same ion specificity for the counterion mobility as for permeability. It has been suggested that the specific counterion binding to polymer charges is an essential factor for ion specificity.
Polymerizable mesoionic 4,6‐dioxo‐1,3‐diazines, 1. Synthesis and photochemical behavior of polystyrenes with mesoionic 4,6‐dioxo‐1,3‐diazines as pendant groups
Authors: Ritter Helmut , Sperber Rolf , Weisshuhn Carl Michael
Published: April 2003

Mesoionic 5‐alkyl‐4,6‐dioxo‐1,3‐diphenyl‐2‐(3‐vinylbenzylthio)‐1,3‐diazine (6) was prepared by condensation of alkylmalonic acid (5) with 1,3‐diphenyl‐2‐(3‐vinylbenzyl)isothiourea (4) by use of dicyclohexylcarbodiimide (DCC). Homopolymerization of 6 led to new polystyrene derivatives (7) with mesoionic 4,6‐dioxo‐1,3‐diazines as pendant groups. UV irradiation of 7 yielded polystyrene derivatives with bis(β‐lactam) moieties as pendant groups (8). The change of some physical properties during the irradiation is discussed. 5‐Heptyl‐4,6‐dioxo‐1,3‐diphenyl‐2‐(3‐methylbenzylthio)‐1,3‐diazine (11) and 4‐heptyl‐1‐(3‐methylbenzylthio)‐3,5‐dioxo‐2,6‐diphenyl‐2,6‐diazabicyclo[2.2.0]hexane (12) as low‐molecular‐weight model compounds were synthesized for structural analysis.
Oxidation of 2,6‐di‐tert‐butylphenol by molecular oxygen catalyzed by tetrasodium phthalocyaninatocobalt(II)tetrasulfonate bound to a polymer colloid
Authors: Hassanein Mahmoud , Selim Adel , El‐Hamshary Hany
Published: April 2003

Crosslinked cationic latexes based on polystyrene, poly[styrene‐co‐(methyl methacrylate)] and poly(methyl methacrylate) were prepared by an emulsion polymerization process using 2 mol‐% of a quaternary ammonium surfactant monomer. Phthalocyaninatocobalt(II)tetrasulfonate (CoPcTs) bound to these latexes were found to enhance the rate of autoxidation of 2,6‐di‐tert‐butylphenol in water. All CoPcTs‐latex catalysts were more active than the water soluble CoPcTsNa4. The styrene latex bound with CoPcTs was the most active catalyst. The reaction products were identified as the oxidative coupling products 3,3′,5,55′‐tetra‐tert‐butyl‐4,4′‐dioxo‐1,1′‐bicyclohexadienylidene (DPQ) and 2,6‐di‐tert‐butyl‐1,4‐benzoquinone (BQ). The ratio DPQ/BQ was found to be affected by the nature of microenvironment. The rate of autoxidation catalyzed by CoPcTs bound to the styrene latex was found to be zero order with respect to the phenol concentration. The reaction rates increase with pH in the range 7–9. The rate of autoxidation increases with increasing concentration of CoPcTs from 1,0 · 10−6 to 2,5 · 10−5 mol/L and then it levels off. At constant concentration of CoPcTs in the reaction mixture, the rate as a function of the weight of latex shows a maximum. The rate shows a linear dependence on partial pressure of dioxygen. Recycling of the latex catalyst results in a reduced activity after successive runs.
Amino acids attached to poly(alkylene phosphate)s, 1. Synthesis
Authors: Kaluzynski Krzysztof , Penczek Stanislaw
Published: April 2003

The synthesis of poly(alkylene phosphate)s with attached amino acids was elaborated. Two methods of coupling through P—NH bond were used. They were based on the direct reaction of amino acid esters or N,O‐bis(trimethylsilyl) substituted amino acids with poly(alkylene chlorophosphate)s. The assumed microstructure of the resulting polymers was confirmed by analysis of the 1H, 13C and 31P NMR spectra. Preliminary data on the hydrolytic stability of amino acids modified poly(alkylene phosphate)s are also given.
Preparation of chiral stationary phases based on anionically polymerised (4S,5S)‐4‐methyl‐5‐phenyl‐2‐(4‐vinylphenyl)‐2‐oxazoline
Authors: Terfloth Gerald , Blaschke Gottfried
Published: April 2003

(4S,5S)‐4‐methyl‐5‐phenyl‐2‐(4‐vinylphenyl)‐2‐oxazoline(1) was prepared. The anionic polymerisation of 1 was initiated in toluene with butyllithium (BuLi) at −78°C to afford poly(1) of narrow molecular weight distribution. The resulting poly(1) was immobilised on modified silica gel to give chiral stationary phases for the separation of racemic compounds.
Influence of morphology on the microhardness of poly(ethylene naphthalene‐2,6‐dicarboxylate)
Authors: Rueda Daniel R. , Viksne Armanda , Malers Laimonis , Calleja Francisco J. Baltá , Zachmann Hans G.
Published: April 2003

The microhardness (H) of poly(ethylene naphthalene‐2,6‐dicarboxylate) (PEN) with a wide range of crystallinities, spherulitic morphologies and different lamellar periodicities has been determined. The influence of the temperature and time of crystallization from the glassy state upon the microhardness values has been examined. For structures where primary crystallization is incomplete, it is shown that H increases linearly with the volume fraction of spherulites. For materials where primary crystallization is completed, H depends on the crystallization temperature and appears to be a function of both the crystallinity and the crystal size. The results are discussed in the light of theoretical predictions of hardness.
Preparation and characterization of photoresponsive poly(methyl methacrylate) microspheres bearing phosphorylcholine‐analogous and spirooxazine moieties
Authors: Sugiyama Kazuo , Nakano Hisashi , Ohga Koji
Published: April 2003

The photoresponsive copolymer microspheres [poly(MAIP‐co‐MMA)] were prepared from the emulsifier‐free emulsion copolymerization of 2‐[2‐(methacryloyloxy) ethyldimethylammonio]‐ethyl indolinonaphthooxazine phosphate (MAIP) and methyl methacrylate (MMA). From the kinetics of the copolymerization of MAIP and MMA, it was found that the initial rate of polymerization of MMA increased by the addition of a small amount of MAIP. From the X‐ray photoelectron spectroscopy (XPS) measurements MAIP moiety was found to be located on the surface of a particle. The introduction of a MAIP moiety into poly(MMA) microspheres results in a decrease in the amount of bovine serum albumin (BSA) adsorbed. A photoresponsive adsorption of BSA on poly(MAIP‐co‐MMA) microspheres was observed with spirooxazine‐merocyanine photoisomerization caused by UV irradiation.
Rheological study of the kinetics of photoinitiated free radical polymerizations with the quartz microbalance
Authors: Ottersbach Peter , Lennarz Klaus , Bargon Joachim
Published: April 2003

Using a quartz microbalance operating in solutions, a very sensitive determination of the increasing viscosity during the very early stages of polymerization reactions is possible in a continuous fashion. Kinetic data have been obtained for methyl methacrylate as the monomer and benzoin, its methyl ether, and 2,2‐dimethoxy‐2‐phenylacetophenone as photoinitiators using an excimer laser operating at 351 nm. This in situ method represents a very sensitive, convenient, and inexpensive technique for obtaining kinetic data under a variety of boundary conditions including photopolymerization, the example outlined here.
On the influence of temperature in the physical and mechanical characterization of polymer oxidation profiles
Authors: Dole Patrice , Chauchard Jacques
Published: April 2003

The diffusion‐limited thermodegradation of a poly[ethylene‐co‐(methyl acrylate)] rubber was studied using an original pinpoint dynamic mechanical analysis (PDMA). The importance of the temperature of the analysis in the physical and mechanical determination of oxidation profiles was clearly illustrated. The variations of the tan δ (δ: loss angle) at the glass transition temperature allows the determination of the apparent activation energy of the diffusion‐limited thermooxidation phenomena.
Thermodynamics of mixing of propylene oxide oligomers with different end groups and of statistical and block cooligomers of ethylene oxide and propylene oxide in tetrachloromethane
Authors: Killmann Erwin , Cordt Frank , Möller Friedrich , Zellner Helmut
Published: April 2003

Mixing enthalpies and Gibbs energies of liquid propylene oxide oligomers with hydroxyl and methoxy end groups and of block and statistical cooligomers of ethylene oxide and propylene oxide in tetrachloromethane are obtained by microcalorimetry and vapour pressure measurements. The thermodynamic excess quantities ΔH, ΔGE and ΔSE of mixing are influenced by induced dipol interactions of the ether segments with CCl4 and by the hydrogen bond interactions of the OH end groups. An expanded theoretical treatment using the Huggins approach of quasichemical equilibrium between the contacting segment surfaces is successfully applied on the experimental results.
Copolymérisation de la N‐acryloyl‐L‐valine et de la N‐acryloyl‐L‐phénylalanine avec l'acrylamide
Authors: Camail M. , Maesano J. C. , Margaillan A. , Vernet J. L.
Published: April 2003

The synthesis of N‐acryloyl‐L‐valine (NAVAL) and N‐acryloyl‐L‐phenylalanine (NAPHE) have been carried out from L‐valine and L‐phenylalanine. The chiral compounds have been characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and polarimetry. The copolymerization of NAVAL salt, (NAVAL Na, monomer A) or NAPHE salt (NAPHENa, monomer A′) with acrylamide (AM, monomer B) has been investigated using K2S2O8 as initiator, over a range of the feed compositions for NAVALNa (or NAPHENa) from 10 to 100 mol‐%. The compositions of copolymers have been systematically assessed through 13C NMR. The reactivity ratios for the couple A, B were determined as rA = 0,67, rB = 0,91 and for the couple A′, B they have been evaluated to be: rA′ = 0,40, rB = 0,91. The azeotropic composition is located at 21 mol‐% for the couple A, B and at 13 mol‐% for the couple A′, B. Drag reduction effects are obtained with these polymers.
Copolymers of N‐vinyl‐2‐pyrrolidone and 2‐(dimethylamino)ethyl methacrylate, 3. Viscosity of quaternized copolymers in aqueous solution
Authors: Deboudt Karine , Delporte Michèle , Loucheux Claude
Published: April 2003

N‐Vinyl‐2‐pyrrolidone (VP) — 2‐(dimethylamino)ethyl methacrylate (DMAEM) copolymers were quaternized with octyl, dodecyl or hexadecyl bromide. The behaviour of the modified copolymers in aqueous solutions was studied by viscosimetry. As typical of classical polyelectrolytes, by increasing the ionic strength of the solutions, their viscosity decreases. Since the DMAEM mole fraction in the modified copolymers is low, the pH of the solutions does not have a great influence on the extension of the macromolecules. The influence of the size of the alkyl chains and of the mole fraction of quaternized units were studied: the formation of hydrophobic microdomains is easier for copolymers which have a low fraction of long quaternized units than for copolymers with a high mole fraction of short quaternized units.
A UV/visible spectroscopic study of water‐soluble conjugated polyenes prepared via the ring‐opening metathesis polymerization reaction
Authors: Amir‐Ebrahimi V. , Byrne Declan , Hamilton James G. , Rooney John J.
Published: April 2003

A series of water‐soluble conjugated polyenes, based on the poly(furanylvinylene) structure, have been prepared from readily available starting materials using ring‐opening metathesis polymerization followed by dehydrogenation of the resulting polymer. 13C NMR analysis of the precursor polymers shows that the stereochemistry of the main‐chain double bonds varies from 93% trans to 10% trans and is retained in the water‐soluble derivatives, allowing different degrees of extended conjugation. This is reflected in the UV/vis spectra of the materials. The polymers may be cast into films from aqueous solution, and the UV/vis spectra exhibit vibrational fine structure indicative of conformational rigidity; significantly this fine structure is retained on redissolving the high‐trans but not the high‐cis films. The absorption maximum of the visible spectrum shows a stronger pH dependence in the high‐cis polymers than in the high‐trans, and this is interpreted in terms of the different modes of hydrogen bonding which cis and trans units can adopt.
A stereochemical and statistical analysis of metallocene‐promoted polymerization
Authors: Farina Mario , Di Silvestro Giuseppe , Terragni Alberto
Published: April 2003

The metallocene catalysts active in propylene polymerization can be divided into five classes, depending on whether the catalytic sites are chirotopic or not, and on the symmetry relationship between the catalytic sites bound to the same metal atom. Under the hypothesis of a purely alternating mechanism for propagation, class III and class IV catalysts, respectively, give rise to prevailingly isotactic and syndiotactic polymers. Four probabilistic schemes have been developed for interpreting the stereosequence distribution of polypropylene in terms of pentads. They take into account the two sources of steric control, chirotopicity of the catalyst site and configuration of the chain end, and the presence, besides the alternating mechanism, of successive addition steps at the same catalytic site.
Lithium alkylnickelate and alkylpalladate bimetallic “ate” complexes as initiators for anionic polymerization of methyl methacrylate
Authors: Mardare Daniela , Matyjaszewski Krzysztof
Published: April 2003

Anionic‐coordinative polymerization of methyl methacrylate (MMA) was carried out in the presence of new bimetallic initiators based on lithium alkylnickelates and alkylpalladates in tetrahydrofuran, at −78°C. Well‐defined poly(methyl methacrylate), PMMA, with molecular weights increasing linearly with conversion and relatively narrow polydispersities (M̄w/M̄n = 1,26 to 1,4) were prepared by initiation with some of the “ate” complexes. In the presence of lithium “ate” Ni‐based complexes, PMMA with enhanced syndiotacticity [(rr) = 73 to 75%] was formed.
Polymerization in microemulsions — a new approach to ultrafine, highly functionalized polymer dispersions
Authors: Antonietti Markus , Basten Rainer , Lohmann Sabine
Published: April 2003

Polymerization in microemulsions is a new polymerization technique which allows the synthesis of ultrafine latex particles within the size range 5 nm < R < 50 nm and with narrow size distribution. This article presents a short review of the current literature in this field. Beside a short introduction into some kinetic aspects of polymerization in microemulsions, we mainly focus on the synthetic aspects of this technique such as the particle size control and the analysis of the diversity of surfactants which allow formation of polymerizable microemulsions. The control of the chemical functionality or nature of the particle surfaces which may be as large as 300 m2/g and its use for chemistry is a further topic of this paper. A personal analysis of the actual future trends in this rapidly developing field such as the polymerization of complex morphologies is closing the paper.
Study on the miscibility of poly(2‐hydroxyethyl methacrylate)/poly(styrene‐co‐acrylamide) blends by nonradiative energy transfer fluorescence spectroscopy
Authors: Zhu K. J. , Ji Wang
Published: April 2003

The miscibility of poly(2‐hydroxyethyl methacrylate)/poly(styrene‐co‐acrylamide) (PHEMA/PSAm) blends was investigated by nonradiative energy transfer fluorescence spectroscopy using anthracene‐labeled PHEMA and carbazole‐labeled PSAm. The results show that the ratio of the carbazole and anthracene emission intensity, Ic/Ia, passes through a minimum at 47 to 57 mol‐% of acrylamide in PSAm copolymers in the blends, indicating that a ‘miscible window’ exists. It also was found that the results are consistent with those obtained by differential scanning calorimetry. The driving force for the miscibility of PHEMA/PSAm may be explained with a mean‐field theory.
Synthesis of organosilicon‐containing macromonomers through an anionic polyaddition reaction
Authors: Nagasaki Yukio , Tsuruta Teiji
Published: April 2003

Lithium diisopropylamide (LDA) induces metalation reaction of 4‐(trimethylsilylmethyl)‐styrene (SMS) to form lithiated SMS (SMSLi). SMSLi initiates the anionic polymerization of SMS to form oligomers with a polymerizable vinyl end‐group. Mechanistic studies revealed that the propagation proceeds mainly by the addition reactions of SMSLi to the double bond of preformed oligomers in the early stage of the polymerization. In the later stage of the polymerization, propagations between preformed oligomers take place concurrently. The extent of polyaddition enchainments in the oligomers was found to increase when the reaction was carried out keeping the monomer concentration as low as possible. Reactivities of the organosilicon‐containing macromonomers were also estimated by UV, MO calculations, and radical homopolymerization.
Polymers from multifunctional isocyanates, 10. Thermotropic polyurethanes from triad liquid‐crystalline diesterdiisocyanates
Authors: Mormann Werner , Brahm Martin
Published: April 2003

Binary hard‐segment type polyurethanes from para‐linked triad aromatic or cycloaliphatic diisocyanatodiesters (1,4‐phenylene dibenzoate, diphenyl terephthalate, diphenyl trans‐1,4‐cyclohexanedicarboxylate and dicyclohexyl trans‐1,4‐cyclohexanedicarboxylate) and aliphatic diols as chain extenders are described. Due to the favorable aspect ratio of the triad mesogens most of the polyurethanes have an enantiotropic (nematic) mesophase. The influence of substituents in the mesogen and of the chain extender on the thermal transitions of the polyurethanes was studied and compared with the properties of the parent isocyanates.
Polymers from multifunctional isocyanates, 11. Thermotropic copolyurethanes from triad diesterdiisocyanates
Authors: Mormann Werner , Benadda Saria , Brahm Martin
Published: April 2003

Two series of hard‐segment type polyurethane copolymers from para‐linked triad and diad aromatic or cycloaliphatic diisocyanatoesters using aliphatic low‐molecular‐weight diols as chain extenders are described. The first series has been made from one diisocyanate and two different chain extenders, the second from two different diisocyanates and one chain extender. The influence of the copolymer composition on the thermal transitions has been studied. Crystalline and glassy polyurethanes can be made with a wide range of isotropization temperatures. Systematic variation of the mole fraction of either the isocyanates or the chain extenders gives clearing transitions between those of the two binary polymers. An almost linear relationship between clearing temperature and the composition was found for polymers prepared from two isocyanates. With two different chain extenders, isotropization temperatures deviate slightly from a linear relationship.
X‐ray structural studies of various octyl‐substituted polythiophenes
Authors: Mårdalen Jostein , Fell Hans Jörg , Samuelsen Emil J. , Bakken Eivind , Carlsen Per H. J. , Andersson Mats R.
Published: April 2003

The structure of poly(octylthiophene)s and alternating octylthiophene‐thiophene‐copolymers with a varying degree of intrachain regularity was studied by means of X‐ray diffraction and optical absorption measurements. Although these polymers show a varying degree of crystallinity, evidence is found that they all tend to pack as relatively straight parallel chains. The lateral packing distance depends strongly on the regularity and the relative amount of alkyl side chains. Generally poly(thiophene)s with a larger relative amount and higher stereoregularity of the octyl side chains tend to pack more ordered. On the other hand, a large conjugation length (high degree of chain planarity), as revealed by optical absorption spectroscopy, and a crystalline packing of the polymer chains are not found to be interdependent. For the polymer with highest degree of crystallinity two surprisingly different crystalline structures were found for the two versions with different regularity, viz. poly(3‐octylthiophene) and poly(3,3′‐dioctyl‐2,2′ bithiophene). For the latter we find evidence of a polymer chain twist between adjacent head‐to‐head coupled thiophene rings, and we propose a structural model for its crystalline packing. Our new model can explain previously measured differences in spectroscopic and transport‐related properties for these two stoichiometrically identical polymers.
Crosslinking copolymerization of cyclic ketenacetals with low shrinkage in volume
Authors: Schulze Thomas , Klemm Elisabeth
Published: April 2003

The copolymerization of 9,9‐dimethyl‐4‐methylene‐3,5,8,10‐tetraoxabicylco[5.3.0]decane (4) with 3,9‐bismethylene‐2,4,8,10‐tetraoxaspiro[5.5]undecane (5) was investigated. While 4 polymerizes after radical attack to form highly viscous linear polyesters with a number‐average molecular weight of 5000, the addition of 5 in variable amounts leads to insoluble samples. It is shown that the material properties can be controlled by using various contents of 5 in the storable and persistable monomer 4. According to the application purpose, it is possible to produce gel‐like or rubber‐like as well as hard polymer samples.
Stability of solutions of aromatic polyamides containing carborane units in the main chain
Authors: Gladkova Elena A. , Petrus Vladimír , Horský Jiří
Published: April 2003

The stability of aromatic polyamide chains containing 1,7‐dicarba‐closo‐dodecaborane units was investigated in dilute solution by viscometry and sedimentation analysis at 25°C. Traces of impurities in dimethylformamide bring about degradation of the polymer and formation of polyanions, which become manifest in the viscosity by the polyelectrolyte effect. Neutral salts suppress this effect. Degradation is not hindered in an inert atmosphere. The solutions in N,N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone are also unstable. No degradation occurs in solutions in tetrahydrofuran stabilized with 2,6‐di‐tert‐butyl‐4‐methylphenol. Hence, reliable measurements of the molecular characteristics of this polymer can be carried out only in stabilized peroxide‐free tetrahydrofuran.
End‐group analysis of poly(phenyl glycidyl ether), 3. Isopropoxy and chlorine groups using 1H and 13C nuclear magnetic resonance
Authors: Ronda Joan Carles , Serra Angels , Mantecón Ana , Cádiz Virginia
Published: April 2003

Non‐hydroxylic end‐groups in the soluble fraction of poly(phenyl glycidyl ether) (PPGE) obtained with the aluminium isopropoxide (AIP)/ZnCl2 initiator system are studied using nuclear magnetic resonance (NMR) spectroscopy. To make assignments, model compounds are synthesized and several PPGEs are prepared with various initiator systems. Isopropoxy and chlorine groups are identified and quantified using NMR spectroscopy and microcoulometry, respectively. Primary and secondary carbons attached directly to OiPr and Cl are detected by NMR spectroscopy, but, as can be expected, the primary ones are more plentiful due to the fact that they come from the more probable attack in this mechanism of ring‐opening. Other unsaturated terminal groups are also investigated but their presence cannot be detected.
Cationic ring‐opening oligomerization of hexamethylcyclotrisilazane and octamethylcyclotetrasilazane
Authors: Duguet Etienne , Soum Alain
Published: April 2003

The study of the ring‐opening oligomerization of hexamethylcyclotrisilazane (D3NH) and octamethylcyclotetrasilazane (D4NH), initiated by methyl triflate in 1,2‐dichloroethane, was carried out. Size‐exclusion chromatography (SEC) analysis indicated the occurrence of an equilibrated reaction between macrocycles such as (SiMe2NH)n (with 3 ≤ n ≤ 13) (Me:CH3). Kinetic measurements showed that these oligomerizations are first order relative to both monomer and active center concentrations at the beginning of the reaction. The initial rate constants of propagation (kpx)0 and the ratios of propagation and back‐biting ones (kpx/kx) were estimated. Complementary experiments allowed us to propose a mechanism of the oligomerization.
Studies on the phosphorylating polycondensation catalyzed by 4‐dimethylaminopyridine
Authors: Mao Hai‐Quan , Zhuo Ren‐Xi , Fan Chang‐Lie , Jiang Xue‐Song , Liu Wu‐Ping , Yi Hong
Published: April 2003

The phosphorylating polycondensation in solution catalyzed by 4‐dimethylaminopyridine (DMAP) was studied for the first time. The polymerization rate and the average molecular weight of the polyphosphate are increased by using DMAP as a catalyst. The influence of reaction conditions on the catalytic activity of DMAP were preliminarily investigated.
Intermolecular nonradiative energy transfer. Effect of spacer length carrying donor and acceptor fluorophores in water‐soluble copolymers of poly[N‐(2‐hydroxypropyl)‐methacrylamide]
Authors: Vyprachtický Drahomír , Pokorná Veronika , Mikeš František
Published: April 2003

Copolymers of monomers containing donor (carbazole) and acceptor (dansyl) fluorophores with N‐(2‐hydroxypropyl)methacrylamide (HPMA) with “low” and “high” contents of the fluorophores were prepared. At any given fluorophore concentration, the efficiency of nonradiative energy transfer (NET) is always higher for polymers with a lower content of fluorophore labels. At higher concentrations of fluorophore, the mutual interpenetration of the polymer coils reduces this difference. Copolymers of HPMA containing donor and acceptor fluorophores attached to the end of “short” and “long” side chains were synthesized. Increase in NET between copolymers carrying fluorophores at the end of the aliphatic “long” spacer was interpreted as due to hydrophobic interaction of long methylene side chains. The fluorescence quantum yield of carbazole fluorophores in the model compound and in copolymers are discussed in terms of solvent polarity and the polarity of the polymer microenvironment.
Microemulsion polymerization of butyl acrylate, 3. Effect of the monomer concentration
Authors: Capek Ignác , Potisk Pavol
Published: April 2003

The oil‐in‐water (o/w) microemulsion polymerizations butyl acrylate initiated with a watersoluble (ammonium peroxodisulfate, AP) and/or and oil‐soluble (dibenzoyl peroxide, DBP) radical initiator at different monomer feed compositions and monomer concentrations were investigated. The rate of polymerization shows nucleation and termination intervals. The rate of polymerization is found to increase with the BA concentration. The polymerization is faster with AP than with DBP. The average number of radicals per particle increases exponentially with both the monomer concentration and the particle size. The number of particles decreases with monomer concentration. The molecular weights parallel the rate of polymerization and are larger in the systems with DBP.
Photolysis, thermolysis, and protolytic decomposition of a triazene polymer in solution
Authors: Nuyken Oskar , Stebani Jürgen , Lippert Thomas , Wokaun Alexander , Stasko Andrej
Published: April 2003

The depolymerization of a triazeno‐group containing photopolymer, poly[oxy‐1,4‐phenyleneazo(methylimino)hexamethylene(methylimino)azo‐1,4‐phenylene], is investigated in a tetrahydrofuran (THF) solution. Irradiation of the material leads to a clean decomposition of the photolabile polymer, as monitored by UV spectroscopy and gel‐permeation chromatography (GPC). As compared to the photolysis in THF solution, the light‐induced decomposition rate of a polymer in a polymer film is shown to be much slower. The highly photosensitive triazeno group also decomposes thermally at temperatures above approx. 220°C. The kinetics of thermal degradation of the polymer in substance was investigated at a temperature of 256°C, and monitored by GPC measurements. During this decomposition, one first observes the development of higher molar‐mass fractions, which result from grafting reactions of primary radicals. Upon further thermolysis the triazene polymer is completely degraded to low‐molar‐mass products. The volatile decomposition products were identified by gas chromatography/mass spectrometry (GC/MS) analysis. The protolytic decomposition, which represents the retrosynthesis of the triazene polymer, was studied in a 9:1 mixture of tetrahydrofuran and an aqueous citrate buffer solution. Although the decomposition rate in this solvent mixture is slow, as compared to the depolymerization in diluted hydrochloric acid, a clean decomposition of the triazene polymer is obtained.
Thermal reaction between N‐phenylmaleimide and 2‐allylphenol as a model for the crosslinking reaction in bismaleimide polymerization with diallylbisphenol A
Authors: Reyx Danièle , Campistron Irène , Caillaud Christophe , Villatte Martine , Cavedon Annick
Published: April 2003

The thermal reaction between N‐phenylmaleimide and 2‐allylphenol was taken as a model reaction in order to obtain information about chain extension and crosslinking mechanisms of the thermal curing of bismaleimides with diallylbisphenol A. Isolation (preparative HPLC) and characterization (1H and 13C NMR, FT‐IR, HPLC/SM) of a monoadduct and two original triadducts (principally low molecular weight products of the reaction) and studies as a function of time (0–6h) of this thermally induced reaction (160–250°C) with equimolar quantites of N‐phenylmaleimide and 2‐allylphenol, as well as with an excess of N‐phenylmaleimide, give direct evidence of the occurrence of an ene‐reaction and further Diels‐Alder and retro Diels‐Alder reactions with rise in temperature.