bluuebunny/crossref_metadata_2025 huggingface dataset:
Marfey's reagent: Past, present, and future uses of 1‐fluoro‐2,4‐dinitrophenyl‐5‐L‐alanine amide
Authors: B'Hymer Clayton , Montes‐Bayon Maria , Caruso Joseph A.
Published: February 2003

This article describes some of the uses of Marfey's reagent, 1‐fluoro‐2,4‐dinitrophenyl‐5‐L‐alanine amide (FDAA), a pre‐column derivatizing reagent for the separation of enantiomeric isomers of amino acids and amine compounds. An introduction to the basic implementation of this reagent and its historical development are presented. Actual uses in amino acid, short peptide, and pharmaceutical compounds are included, as well as the advantages and disadvantages over other pre‐column derivatization techniques and direct chromatographic separations. Applications of current interest, including its use as an orthogonal analysis and in enantiomeric purity analysis of selenoamino acids using element specific detection, are also discussed.
Determination of phthalic monoesters in aqueous and urine samples by solid‐phase microextraction–diazomethane on‐fibre derivatization–gas chromatography–mass spectrometry
Authors: Alzaga Roberto , Peña Araceli , Bayona Josep María
Published: February 2003

A solvent‐free analytical methodology for the determination of phthalic monoesters (MPs) with diazomethane on‐fibre derivatization using solid‐phase microextraction–gas chromatography–mass spectrometry (SPME–DOFD–GC–MS) was developed. Among the different SPME fibres evaluated, the polydimethylsiloxane/divinylbenzene (PDMS/DVB) proved to be the most suitable for the determination of four MPs. The diazomethane on‐fibre derivatization (DOFD) procedure was improved, avoiding diethyl ether as solvent. Equilibrium conditions were reached (15 min) and K′MP values were calculated. Under optimum MP extraction conditions (e. g. direct immersion, 4 mL of sample, 25°C extraction temperature, stirring at 1 100 rpm, 20 min extraction time, 10 min derivatization reaction, and pH = 1.5), trace level concentrations of MPs (0.3–8.6 ng/mL) were detected, allowing the simultaneous determination of phthalic diesters (DPs). The overall SPME–GC–MS precision was improved by using four deuterated internal standards. The developed analytical methodology was applied to different environmental water matrices and human urine samples at MP concentrations ranging from 0.1–538 ng/mL. The developed analytical procedure is robust (50 analyses with the same fibre), rapid (40 min), and of low cost, improving the conventional analysis methods in terms of analysis time, background levels, and cost.
Evaluation of corrosion resistance of two engineering alloys in molten salts by electrochemical techniques
Authors: Martínez‐Villafañe A. , Almeraya‐Calderón F. , Gaona‐Tiburcio C. , Chacón‐Nava J. , González‐Rodríguez G.
Published: February 2003

The electrochemical behaviour of two steels typically used in power boilers has been studied in the temperature range from 540°C to 680°C. Two environments were used: a) a synthetic salt mixture of 80% V2O5 − 20% Na2SO4 and b) oil ash collected from a high temperature reheater. Corrosion rates obtained from electrochemical potentiodynamic polarisation curves (Tafel extrapolation) were compared for both steels exposed in each environment. The results showed that increases in temperature resulted in higher corrosion rates, being this effect most notorious above about 620°C. In the synthetic salt, and at temperatures up to about 580°C, both steels showed similar behaviour. With further increases in temperature, the T22 steel was less resistant and, at the highest temperature used here, its corrosion rate was almost seven times higher than that measured for the 347H steel. The results obtained with the natural oil ash for the T22 steel showed a dramatic increase in corrosion rate as temperature goes up over the range used. For the 347H steel, and up to about 580°C, the corrosion rates were similar to those obtained with the synthetic salt. Above 580°C, the corrosion rate measured increased slightly with temperature, being at 680°C about 2.5 times higher than that found by using the synthetic salt. Therefore, an important difference in corrosion rates has been found depending upon the corrosive salt used. This is an important result because imply that, at least for materials used in fossil power plants, more realistic data can be obtained by using natural ashes in the experimental work.
Interactions between polysulphides and stainless steel materials
Authors: Rämö J. , Sillanpää M. , Hyökyvirta O.
Published: February 2003

Ability of polysulphide to enhance the potential of digester materials (S30400, S31603, S32205, S32304) was studied in the impregnation stage of the pulping process. Polysulphides were generated by adding elemental sulphur to alkaline sulphide solutions. Polysulphide levels 0.3–0.48, 1.25–2, 5–8 and 12.5–20 g/l enhanced the potentials of the steels by 70, 90, 170 and 190 mV, respectively. The polysulphide concentrations were calculated values, because concentrations of polysulphides are very difficult to measure in kraft liquors. No weight changes were observed, but slight accumulation of sulphur onto surfaces, particularly onto S31603 was seen in X‐ray fluorescence analysis. Otherwise, differences in behaviour among the steel materials were minimal.
Praxisnaher Nachweis zur Wirksamkeit von VCI‐Korrosionsschutzmitteln an flächigen Proben –Prüfverfahren nach BFSV –
Authors: Eschke K. R. , Petzoldt J. , Tiedemann S.
Published: February 2003

Im Bereich des temporären Korrosionsschutzes metallischer Halbfabrikate hat sich die VCI‐Methode (VCI‐Volatile Corrosion Inhibitor) erfolgreich am Markt etabliert. Die Wirksamkeit der VCI's wurde bisher durch Laborprüfungen (Liefernormen) nachgewiesen, die nur in geringem Maße die Praxisbelastungen wiederspiegelten.

Die Reproduzierbarkeit der Ergebnisse war bisher ebenfalls eingeschränkt. Im Institut für BFSV an der Hochschule für Angewandte Wissenschaften Hamburg (Hamburg University of Applied Sciences) wurde im Rahmen des AIF‐Projektes 12115 (gefördert vom BMWI) ein Prüfverfahren mit einer hohen Korrelation zu den Metalloberflächen in der Praxis und einer guten Reproduzierbarkeit der Prüfergebnisse entwickelt und nachgewiesen.

Zusätzlich wurden Vorgehensweisen zur Ermittlung von realen klimatischen Belastungsprofilen und für ein objektives Beurteilungsverfahren zur Korrosionsgradbestimmung aufgezeigt.
Corrosion behaviour of magnesium sacrificial anodes in tap water
Authors: Andrei M. , di Gabriele F. , Bonora P. L. , Scantlebury D.
Published: February 2003

The effects of applied current, testing time and microstructure on the electrochemical properties of magnesium‐based sacrificial anodes in potable water were evaluated. Galvanostatic tests, potentiodynamic polarisation and scanning electron microscopy (SEM) analyses were used to determine anode efficiency, corrosion rate and microstructures of the Mg‐anodes under study. The contribution of processes as mechanical material loss and hydrogen evolution on the current wastage was investigated. The effect of the different microstructures like those obtained by heat treatments to reduce the intermetallic phase was also tested.
A 13C NMR Study of the Products and Mechanism of the Thermal Oxidative Degradation of Poly(ethylene oxide)
Authors: Mkhatresh Omar A. , Heatley Frank
Published: February 2003

The products and mechanism of the thermal oxidative degradation of poly(ethylene oxide) at 150 °C have been analysed using 13C NMR spectroscopy. The analysis was assisted by the use of distortionless enhancement by polarisation transfer spectra, longitudinal relaxation time measurements, long‐range 13C1H coupling and chemical shift simulation software. The major result of degradation was chain scission resulting in two formate ester chain ends. Minor products were in‐chain esters, peroxy groups, oxymethylene links and hydroxy and methoxy chain ends.

Initial steps for the mechanism of chain scission.

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Initial steps for the mechanism of chain scission.
Macromolecular Design via the Interchange of Xanthates (MADIX): Polymerization of Styrene with O‐Ethyl Xanthates as Controlling Agents
Authors: Destarac Mathias , Brochon Cyril , Catala Jean‐Marie , Wilczewska Agnieszka , Zard Samir Z.
Published: February 2003

Control of the free‐radical polymerization of styrene was achieved using a series of eight xanthates of the general structure RS(CS)OEt as reversible addition fragmentation chain‐transfer agents. The influence of the nature of the R leaving group was explored. It was found that the transfer ability of the xanthate is markedly improved with increasing stability of R and its steric hindrance. Group R strongly influences the Mn evolution profile during polymerization, but only influences the polydispersities to a small extent. The cyanoisopropyl group was shown to be the best leaving group, leading to an increase in the molecular weight during polymerization that was close to linearity. The living character of the polymerization and the high purity of the chain structures were supported by matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry and 13C NMR spectroscopy. A zero‐order dependence of the kinetics of polymerization on the xanthate concentration was observed.

Conversion versus time plots for thermal bulk polymerizations of styrene at 110 °C in the presence of various xanthates.

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Conversion versus time plots for thermal bulk polymerizations of styrene at 110 °C in the presence of various xanthates.
Rheological Properties of Micellar Aqueous Solution of Hydrophobically Modified Poly(ethylene glycol) (C12E25)
Authors: Yamazaki Ritsuko , Inomata Katsuhiro , Nose Takuhei
Published: February 2003

The rheological properties of micellar aqueous solutions of hydrophobically modified ethylene glycol oligomer, poly(ethylene glycol) monododecyl ether (C12E25), have been studied over a wide range of concentration and temperature. The micellar solution of C12E25 exhibits a sol‐gel transition accompanied by a disorder‐to‐order transition of micelle particles. The following conclusions were made: (1) The sol solution behaves like an ordinary viscous liquid of Newtonian flow, presenting no sign of any change in associations. (2) Under shear deformation, the gel exhibits a yield point around the strain of a few per cent, followed by a plastic flow with further deformation. The plastic flow exhibits a strong non‐Newtonian flow. (3) As the shear rate increases, the sol‐gel transition temperature, observed by steady‐flow viscosity, becomes lower with a reduced sharpness of transition. (4) The long‐range structural order of the lattice in the gel, destroyed by the plastic flow, is suggested to substantially recover in 10–100 s.

Concentration dependency on the steady‐flow viscosity at the shear rate of 10 s−1 for C12E25 aqueous solutions at 70 °C. The inset shows the linear–linear plots.

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Concentration dependency on the steady‐flow viscosity at the shear rate of 10 s−1 for C12E25 aqueous solutions at 70 °C. The inset shows the linear–linear plots.
UV‐Curable Azobenzene Polymer Bearing Photo‐Crosslinkable Moiety for Stabilization of Photo‐Fabricated Surface Relief Structure
Authors: Kimura Tatsumi , Kim Jun.‐Young , Fukuda Takashi , Matsuda Hiro
Published: February 2003

In order to find a new class of photo‐processable liquid crystalline (LC) aligning material, five kinds of new maleimide‐based copolymers bearing both azobenzene and cinnamate moieties with different functionalization ratio have been synthesized. The properties of these five copolymers were compared regarding physical and chemical properties that are required for our aim. The photo‐induced surface relief (PSR) gratings could be fabricated on the films of these copolymers using an Ar+ laser (λ = 488 nm), and were successfully immobilized and bleached by UV‐light irradiation that causes photo‐crosslinking of the cinnamate moiety and photo‐degradation of the azobenzene moiety, respectively. The PSR inscription rate and the thermal stability have been investigated regarding the functionalization ratio between cinnamate and azobenzene side chain. The residual ratio of the PSR structure after UV‐curing was increased with increasing photo‐crosslinkable moiety. It was confirmed that the UV‐cured PSR grating structure becomes transparent at visible wavelength and was able to align LC molecules parallel to the grating direction.

Polarized optical microscope image of LC cell aligned by the PMPDC 21‐18 film with UV‐cured PSR structure (0°).

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Polarized optical microscope image of LC cell aligned by the PMPDC 21‐18 film with UV‐cured PSR structure (0°).
Temperature‐Induced Polymorphic Crystals of Poly(butylene adipate)
Authors: Gan Zhihua , Abe Hideki , Doi Yoshiharu
Published: February 2003

The melting behavior, crystal structure, and spherulitic morphology of melt‐crystallized poly(butylene adipate) (PBA) at a temperature range from 25 to 35 °C have been investigated by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and optical microscopy. Two distinct melting behaviors with double peaks have been observed after melt‐crystallizing at different temperatures. X‐ray analysis proves that these two behaviors arise from two forms of PBA crystal structures. The β‐form crystals are formed at temperatures below 31 °C, while the α‐form crystals are formed above 29 °C. When the crystallization temperature is 30 ± 1 °C, a mixture of α‐form and β‐form crystals has been formed. The influences of annealing treatment and sample preparation method on the two forms of PBA crystal structures have been discussed. The results indicate that the low temperature‐formed β‐form crystals are very sensitive to the preparation conditions.

The melting curves at different heating rates for poly(butylene adipate) after melt‐crystallized at 25 °C and 33 °C, respectively.

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The melting curves at different heating rates for poly(butylene adipate) after melt‐crystallized at 25 °C and 33 °C, respectively.
Stereoblock Copolymerization of Propylene and Methyl Methacrylate with Single‐Site Metallocene Catalysts
Authors: Jin Jizhu , Chen Eugene Y.‐X.
Published: February 2003

Sequential stereoblock copolymerization of propylene (P) and methyl methacrylate (MMA) using Group IV single‐site metallocene catalysts efficiently produces PP‐b‐PMMA stereodiblock copolymers. When activated with B(C6F5)3, C2‐symmetric rac‐Et(Ind)2ZrMe2 yields isotactic‐PP‐b‐isotactic‐PMMA diblock copolymer, whereas Cs‐symmetric Me2Si(C5Me4)(tBuN)TiMe2 affords atactic‐PP‐b‐syndiotactic‐PMMA diblock copolymer. In the copolymerization catalyzed by the C2‐symmetric catalyst, a very small amount of PMMA homopolymer formed can be removed from the copolymer by extracting the bulk polymer product with boiling methylene chloride. However, separation of isotactic PP formed if any from the copolymer product approves very difficult, due to very similar solubility between the diblock copolymer and isotactic PP homopolymer in various high‐boiling chlorinated solvents. On the other hand, in the copolymerization catalyzed by the Cs‐symmetric catalyst, both PMMA and atactic PP homopolymers formed in small weight fractions during the copolymerization can be successfully removed from the predominant copolymer product by solvent extraction using boiling heptane. After successful removal of both homopolymers, for example, an atactic‐PP‐b‐syndiotactic‐PMMA diblock copolymer has high molecular weight (Mn = 21 100), narrow molecular weight distribution (PDI = 1.08), high PMMA incorporation (33.8 mol‐% of PMMA), and moderate syndiotacticity for the PMMA block ([rr] ≈ 80%). Furthermore, the comonomer composition in the copolymer can be controlled by the time for propylene polymerization and the conversion of MMA. A pronounced activator effect is observed; when the same Cs‐symmetric catalyst is activated with Ph3CB(C6F5)4, formation of homopolymers is predominated.

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Electrochemical Polymerization of Thianaphthene in Mixed Electrolytes of Boron Trifluoride Diethyl Etherate and Trifluoroacetic Acid
Authors: Xu Jingkun , Shi Gaoquan , Zhang Jiaxin , Hong Xiaoyin
Published: February 2003

Substrate‐supported polythianaphthene (PTN) films have been electrochemically synthesized by direct oxidation of thianaphthene on platinum or stainless steel electrode in mixed electrolytes of boron trifluoride diethyl etherate (BFEE) and trifluoroacetic acid (TFA). The oxidation potentials of the monomer in these media are considerably lower than those in neutral solvents. Increasing the content of TFA in the mixed electrolytes can effectively decrease the oxidation potential and increase the coupling rate of the monomer. On the other hand, a high TFA concentration can result in a negative effect on the properties of the as‐formed polymer. The mixed electrolyte of BFEE + 16.7% TFA was found to be the most suitable medium for the electrosyntheses of PTN. PTN in dedoped state is soluble in usual strong polar organic solvent such as dimethyl sulfoxide (DMSO). Fluorescent spectral studies indicate that the polymer is a blue light emitter.

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16th Polymer Networks Group Meeting
Authors: Geissler Erik
Published: February 2003

This section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de.
Synthesis of High‐Molecular Weight Polymers Based on N,N‐Diallyl‐N‐Methylamine
Authors: Timofeeva Larisa M. , Vasilieva Yuliya A. , Klescheva Natalia A. , Gromova Galina L. , Timofeeva Galina I. , Rebrov Alexandr I. , Topchiev Dmitry A.
Published: February 2003

High‐molecular weight polymers, namely poly(N,N‐diallyl‐N‐methylammonium trifluoroacetate) and poly(N,N‐diallyl‐N‐methylamine), were prepared by radical polymerization of N,N‐diallyl‐N‐methylamine in aqueous solution in the presence of an equimolar amount of trifluoroacetic acid and by polymerization of the newly synthesized equimolecular salt N,N‐diallyl‐N‐methylammonium trifluoroacetate in gentle conditions. We have established that chain termination is controlled by the bimolecular mechanism and that degradative chain transfer to monomer transforms into effective chain transfer (see Scheme). The possibility of controlling the polymerization rate and molecular weight of polymers is demonstrated. The mechanisms of the observed phenomena are discussed.

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Synthesis and Characterization of New Acrylate and Methacrylate Monomers with Pendant Pyridine Groups
Authors: Cui Li , Lattermann Günter
Published: February 2003

To overcome some drawbacks of polyvinylpyridines, new monomers of acrylate and methacrylate type with pendant pyridine groups i.e., 4‐(3‐methacryloylpropyl)pyridine 1a and 4‐(3‐acryloylpropyl)pyridine 1b were successfully prepared, although it turned out to be challenging work to synthesize the acrylate monomer 1b. First polymerization studies showed that the new monomers could be polymerized easily by atom transfer radical polymerization (ATRP). The new polymers show excellent characteristics, such as very good solubility, low glass‐transition temperature, and easy quaternization.

Design and structure of new monomers 1a and 1b.

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Design and structure of new monomers 1a and 1b.
Chemical Modification of a Poly(ethylene terephthalate) Surface by the Selective Alkylation of Acid Salts
Authors: Li Jun , Maekawa Yasunari , Yamaki Tetsuya , Yoshida Masaru
Published: February 2003

Chemical modification of the hydrophilic surface of poly(ethylene terephthalate) (PET) was examined by the selective alkylation of the acid salt on the surface using acyl bromides as an electrophile with catalytic potassium fluoride. The hydrophobicity of the PET surface increased as the alkylation reaction of the hydrolyzed surface proceeded. The chemical incorporation of the alkylation reagents was confirmed by the presence of fluorine peaks in X‐ray photoelectron spectroscopy (XPS) from the fluorinated reagents. Exponential increases were observed in the emission and excitation intensities of fluorescence spectra during the reaction of the surface with a fluorescent reagent. This indicated that the esterification of carboxylic acids on the surface proceeded without deterioration of the reaction even at the later stages. The relation between changes in contact angles and the fluorescence spectra revealed that the hydrophobicity of a surface was quickly restored at the beginning of a reaction.

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Well‐Defined Ruthenium‐Coordinated Block Copolymers of 2‐Vinylpyridine with 2‐(N‐Carbazolyl)ethyl Methacrylate and Their Optical Properties
Authors: Cho Young‐Sun , Lee Hye‐Kyung , Lee Jae‐Suk
Published: February 2003

In order to study the energy‐transfer phenomenon in ruthenium‐coordinated polymers, novel block copolymers from carbazolylethyl methacrylate and 2‐vinylpyridine were prepared by living anionic polymerization; the copolymers possessed varying repeating units and had the desired molecular weight and a narrow‐molecular‐weight distribution. The ruthenium‐coordinated block copolymers were formed by reacting [RuII(tpy)(dmbpy)Cl] with the polymers, in which the pyridine units acted as ligands. Photoluminescence and optical absorption measurements of the coordinated block copolymers were carried out to observe the energy transfer in the complexes. The energy transfer from the carbazole blocks to the ruthenium‐coordinated blocks might take place either by an intra‐ and/or an intermolecular energy‐transfer mechanism. From the optical absorption, photoluminescence, and electroluminescence studies, it was observed that the ease of the energy transfer increased with an increasing number of metal‐complex units.

Normalized electroluminescence spectra of the device (ITO/PEDOT/RuIIL2bpolym/TAZ/Alq3/Ag).

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Normalized electroluminescence spectra of the device (ITO/PEDOT/RuIIL2bpolym/TAZ/Alq3/Ag).
Synthesis of Magnetic Nanocomposite Based on Amphiphilic Polyurethane Network Films
Authors: Kim Ju‐Young , Shin Dong‐Hyun , Ihn Kyo‐Jin , Nam Chang‐Woo
Published: February 2003

Magnetic nanocomposites, showing extremely small coercivity and hysteresis loop, were synthesized using amphiphilic polyurethane networks based on amphiphilic urethane acrylate nonionomer (UAN) precursor chains. Three kinds of UAN gel films were synthesized through UV‐curing of UAN chains in the absence of a solvent, or crosslinking polymerization of UAN/water and UAN/DMAc mixtures. Even though these gel films were synthesized with the same UAN, these UAN gel films had very different microstructures depending on the preparation conditions; as a consequence, magnetic composites prepared with these crosslinked films exhibited very different size and morphology of magnetic nanoparticles. Atomic force microscopy and mechanical property measurements showed that UAN gel film (UANH) synthesized with UAN/water mixture had the highly microphase‐separated structures whereas the gel films synthesized via UV‐curing (UANV) or polymerization of UAN/DMAc mixture (UAND) had relatively homogeneous structures. The largest ellipsoidal particles were formed in UANH gel films and the smallest ellipsoidal particles and rod‐shaped particles were made up in UANV gel and UAND gel film, which was confirmed by transmission electron microscopy.

Transmission electron micrograph of magnetic composite film prepared with UANV.

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Transmission electron micrograph of magnetic composite film prepared with UANV.
Glass‐Transition Temperature (Tg) of Free‐Radically Prepared Polyacrylonitrile by Inverse Gas Chromatography, 2. Molecular‐Weight Dependence of Tg of Two Different Types of Aqueous Polymers
Authors: Minagawa Masatomo , Kanoh Hiroyasu , Tanno Satoshi , Satoh Masaru
Published: February 2003

The molecular‐weight dependence of the glass‐transition temperature (Tg) of a series of atactic polyacrylonitriles (PAN)s was studied by inverse gas chromatographic (IGC) analysis. PANs having different molecular weights were prepared by either; (i) the addition of isopropyl alcohol as a chain‐transfer agent, or (ii) a scission reaction induced by the addition of alkali (NaOH) to a solution (N,N‐dimethylformamide solution, at 25 °C) of the resulting polymer. The intrinsic viscosity [η] was in the range of 10.9–0.1 (dl · g−1), which corresponds to a viscosity‐averaged molecular weight (Mv) of 1 590 000–3 000. As part of the results, a side reaction, which saw the conversion of the nitrile (CN) groups of PAN into amide (CONH2) and/or carboxylic acids (COOH) groups by alkali, was found to occur. The typical molecular‐weight dependence of the Tg in free‐radically prepared PAN was discussed in connection with a chain‐transfer mechanism in an aqueous medium.

Molecular‐weight dependence of the Tg for PAN (WA). An error bar is given by a short vertical arrow.

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Molecular‐weight dependence of the Tg for PAN (WA). An error bar is given by a short vertical arrow.
Oxidative Coupling Copolymerization of 4‐Methyltriphenylamine with Arenes
Authors: Strzelec Krzysztof , Fugino Nobutoshi , Ha Jaekook , Ogino Kenji , Sato Hisaya
Published: February 2003

A novel synthetic method for the preparation of high‐molecular‐weight conjugated polymers is presented. It consists of the oxidation copolymerization of different arenes with triphenylamine. The structure of the copolymers was characterized by 1H and 13C NMR spectra. The copolymers have good solubility in common organic solvents and are thermally stable. Photoluminescence (PL) spectra (see Figure) showed that the color of emission depends on the type of arene units in the copolymer chain. Cyclic voltammetry (CV) measurements revealed electrochemical activity of the copolymers.

PL spectra of the copolymers.

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PL spectra of the copolymers.
Synthesis, Characterization, and Intramolecular End‐to‐End Ring Closure of α‐Isopropylidene‐1,1‐dihydroxymethyl‐ω‐diethylacetal Polystyrene‐block‐polyisoprene Block Copolymers
Authors: Schappacher Michel , Deffieux Alain
Published: February 2003

Cyclic polystyrene‐block‐polyisoprenes of controlled dimensions have been synthesized for the first time by the direct coupling of α‐isopropylidene‐1,1‐dihydroxymethyl‐ω‐diethylacetal‐heterodifunctional linear polystyrene‐block‐polyisoprene precursors previously prepared by living anionic polymerization. Cyclization is achieved under high dilution by intramolecular coupling of the polymer ends under acid catalyst conditions. Using this strategy polystyrene‐block‐polyisoprene macrocycles of controlled chain dimensions are prepared in high yield (> 90%). Pure cycles were finally recovered by flash chromatography. The synthesis and characterization of both the linear α,ω‐heterodifunctional polystyrene‐block‐polyisoprenes block copolymers precursors and of the corresponding cyclized chain architectures are reported.

200 MHz 1H NMR spectrum (CDCl3) of cyclized polystyrene‐block‐polyisoprene copolymer (Mn = 12 000).

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200 MHz 1H NMR spectrum (CDCl3) of cyclized polystyrene‐block‐polyisoprene copolymer (Mn = 12 000).
Propylene Polymerization with Bis(phenoxy‐imine) Group‐4 Catalysts Using iBu3Al/Ph3CB(C6F5)4 as a Cocatalyst
Authors: Saito Junji , Onda Mitsuhiko , Matsui Shigekazu , Mitani Makoto , Furuyama Rieko , Tanaka Hidetsugu , Fujita Terunori
Published: February 2003

The catalytic behavior of three bis(phenoxy‐imine) group‐4 transition‐metal complexes (M = Ti, Zr, Hf), with iBu3Al/Ph3CB(C6F5)4 cocatalyst systems towards propylene polymerization was investigated under atmospheric pressure at 25 °C. The Ti complex produced ultrahigh‐molecular‐weight atactic poly(propylene), whereas Zr and Hf complexes formed high‐molecular‐weight isotactic poly(propylene)s via a site‐control mechanism. The isotactic poly(propylene) obtained with the Hf complex displayed a high melting temperature of 123.8 °C.

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Coils, Rods and Rings in Hydrogen‐Bonded Supramolecular Polymers
Authors: Tessa ten Cate A. , Sijbesma Rint P.
Published: February 2003

The article discusses the development and properties of supramolecular polymers based on quadruple hydrogen bonds between self‐complementary ureidotriazine (UTr) and ureidopyrimidinone (UPy) functional groups. The high association constant with which these groups dimerize leads to polymers with a high degree of polymerization in isotropic solution. Application of these units for the functionalization of telechelic polymers results in new materials with mechanical properties approaching those of covalent polymers, but with a much stronger temperature‐dependent behavior. Solvophobic interactions between the hydrogen bonding moieties may be used to obtain supramolecular polymers with a well defined helical columnar architecture. Another consequence of the high dimerization constant of the UPy group is the phenomenon of a critical concentration in solutions of many bifunctional monomers. Below this concentration, only cycles are present, while above the critical concentration, the amount of cycles remains constant, and a polymer is formed. Conformational properties of the linker units are used to control the equilibrium between polymers and cycles, and are proposed to form a promising strategy toward tunable materials.

Supramolecular polymer material with elastomeric properties resulting from functionalization with UPy groups. (Reproduced with permission. © John Wiley & Sons, Inc.)

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Supramolecular polymer material with elastomeric properties resulting from functionalization with UPy groups. (Reproduced with permission. © John Wiley & Sons, Inc.)
Atom‐Transfer Radical Polymerization of 2‐(N,N‐Dimethylamino)ethyl Acrylate
Authors: Zeng Faquan , Shen Youqing , Zhu Shiping
Published: February 2003

ATRP of 2‐(N,N‐dimethylamino)ethyl acrylate (DMAEA) was investigated using CuBr or CuCl with different multidentate ligands. The catalyst was found active for DMAEA polymerization when ligated with tris[2‐(N,N‐dimethylamino)ethyl]amine. Good control over molecular weight was achieved, but quaternization of the terminal monomeric/polymeric tertiary amine by the CBr group of polyDMAEA caused chain termination. Using a chloride‐based system helped to suppress chain termination. Amphiphilic poly(methyl acrylate)‐block‐polyDMAEA was synthesized using polyMA as a macroinitiator.

Molecular weights and polydispersities of polyDMAEA versus DMAEA conversion for different catalyst systems.

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Molecular weights and polydispersities of polyDMAEA versus DMAEA conversion for different catalyst systems.
Kinetic Study and New Applications of UV Radiation Curing
Authors: Decker Christian
Published: February 2003

Highly crosslinked polymers can be readily synthesized by photoinitiated polymerization of multifunctional monomers or functionalized polymers. The reaction can be followed in situ by real‐time infrared (RT‐IR) spectroscopy, a technique that records conversion versus time curves in photosensitive resins undergoing ultrafast polymerization upon UV exposure. For acrylate‐based resins, UV‐curing proceeds with long kinetic chains (7700 mol/radical) in spite of the high initiation rate. RT‐IR spectroscopy proved very valuable in assessing the influence of various parameters, such as initiation efficiency, chemical structure of the telechelic oligomer, light intensity, inhibitory effect of oxygen, on polymerization kinetics. Interpenetrating polymer networks can be rapidly synthesized by means of UV irradiation of a mixture of difunctional acrylate and epoxy monomers in the presence of both radical and cationic‐type photoinitiators. The same UV technology can be applied to crosslink solid polymers at ambient temperature, which bear different types of reactive groups (acrylate and vinyl double bonds, epoxy ring). UV radiation curing has been successfully used to produce within seconds weathering resistant protective coatings, high‐resolution relief images, glass laminates and nanocomposites materials.

Photoinitiated crosslinking polymerization.

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Photoinitiated crosslinking polymerization.
Automated Scanning Probe Microscopy as a New Tool for Combinatorial Polymer Research: Conductive Carbon Black/Poly(dimethylsiloxane) Composites
Authors: Neffati Riadh , Alexeev Alexander , Saunin Sergey , Brokken‐Zijp José C. M. , Wouters Daan , Schmatloch Stefan , Schubert Ulrich S. , Loos Joachim
Published: February 2003

A systematic investigation into the surface properties of siloxane rubber/carbon black (CB) nanocomposites has been performed, using an automated scanning probe microscope. In this way the influence of CB concentration and curing rate of the siloxane rubber matrix on roughness and conductivity of the composites was studied. Decreasing the curing rate while keeping the CB concentration resulted in a decrease in both roughness and surface conductivity, which can be explained by an additional siloxane‐rubber layer formed during curing.

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Combinatorial Mapping of Surface Energy Effects on Diblock Copolymer Thin Film Ordering
Authors: Smith Archie P. , Sehgal Amit , Douglas Jack F. , Karim Alamgir , Amis Eric J.
Published: February 2003

Combinatorial gradient techniques are used to map the morphology dependence of thin symmetric diblock copolymer films on film thickness and substrate surface energy. An inversion from symmetric to anti‐symmetric lamellar morphology occurs with a progressive change in surface energy. An intermediate neutral region is found between these limiting types of ordering. The width ω of this transitional energy range scales as a power of copolymer mass M, ω ∝ M1.9.

Optical photograph of a combinatorial map of the thin‐film block‐copolymer morphology on a film thickness and surface energy gradient. Island and holes on the surface scatter light causing the film to appear cloudy (lighter in color) in the areas where they exist. The darker areas do not have surface features and do not scatter light.

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Optical photograph of a combinatorial map of the thin‐film block‐copolymer morphology on a film thickness and surface energy gradient. Island and holes on the surface scatter light causing the film to appear cloudy (lighter in color) in the areas where they exist. The darker areas do not have surface features and do not scatter light.
Application of a Parallel Synthetic Approach in Atom‐Transfer Radical Polymerization: Set‐Up and Feasibility Demonstration
Authors: Zhang Huiqi , Fijten Martin W. M. , Hoogenboom Richard , Reinierkens Roy , Schubert Ulrich S.
Published: February 2003

A parallel synthetic approach toward homogeneous atom‐transfer radical polymerization of methyl methacrylate has been successfully applied by utilizing an automated synthesizer. Experimental set‐up, automated parallel synthesis and purification of the polymers via a solid‐phase extraction set‐up, as well as online and offline measurements of the molecular weights and monomer conversion are described in detail. In addition, a comparison with conventional experiments in the laboratory is provided.

Kinetic plots of ln([M]0/[M]) versus reaction time of the ATRP of MMA in p‐xylene at 90 °C conducted in an automated synthesizer (three parallel reactions, ○, ▵, ⋄) and in a conventional set‐up (▪).

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Kinetic plots of ln([M]0/[M]) versus reaction time of the ATRP of MMA in p‐xylene at 90 °C conducted in an automated synthesizer (three parallel reactions, ○, ▵, ⋄) and in a conventional set‐up (▪).
Fast Liquid Chromatography for High‐Throughput Screening of Polymers
Authors: Pasch Harald , Kilz Peter
Published: February 2003

Liquid chromatography of polymers is traditionally a slow technique with analysis times of typically 30 min per sample. For the application of liquid chromatographic techniques to combinatorial materials research the analysis time per sample must be reduced considerably. Analysis time in SEC can be reduced to about 2 min per sample when high‐throughput columns are used. For HPLC small columns with improved separation efficiencies can be used. As compared to conventional technology, time savings of more than 80% are achieved.

Chromatogram from conventional SEC column compared to high‐speed SEC column tested on an identical instrument with polystyrene standards in THF.

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Chromatogram from conventional SEC column compared to high‐speed SEC column tested on an identical instrument with polystyrene standards in THF.
Automated Raman Spectroscopy as a Tool for the High‐Throughput Characterization of Molecular Structure and Mechanical Properties of Polyethylenes
Authors: Gabriel Claus , Lilge Dieter , Kristen Marc O.
Published: February 2003

Raman spectroscopy, which does not require a time‐consuming sample preparation, is described as an analytical tool for the high‐throughput characterization of polyethylenes. The content of comonomer and the amount of methyl groups per 1 000 carbon atoms of polyethylenes can be predicted from Raman spectra using multivariate data analysis. In addition, macroscopic properties, such as density and elastic modulus as well as yield stress, can be derived from Raman spectra.

Raman spectra of selected metallocene‐catalyzed polyethylenes of different comonomer content.

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Raman spectra of selected metallocene‐catalyzed polyethylenes of different comonomer content.
High‐Throughput Fabrication, Performance Testing, and Characterization of One‐Dimensional Libraries of Polymeric Compositions
Authors: Potyrailo Radislav A. , Wroczynski Ronald J. , Pickett James E. , Rubinsztajn Malgorzata
Published: February 2003

A new general approach for rapid performance‐screening of polymer compositions is provided. Multiple compositions are generated as one‐dimensional libraries in a microextruder with step‐ or gradient‐composition changes in 2–10 g of polymer in < 1 min. To accelerate testing, environmental stress is applied to only local regions, followed by high‐sensitivity spatially resolved characterization. We applied our methodology for weathering of arrays of polymeric compositions and provided ranking of polymer/UV absorber compositions equivalent to traditional weathering data while achieved 20 times faster.

Sampling and measurement strategies for HT analysis of combinatorial 1D polymeric libraries: (1) spectroscopic monitoring of chemical properties, (2) in‐situ monitoring of mass and viscoelastic properties, (3) scanning spectroscopic analysis, and (4) spectroscopic imaging of a coiled polymeric array.

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Sampling and measurement strategies for HT analysis of combinatorial 1D polymeric libraries: (1) spectroscopic monitoring of chemical properties, (2) in‐situ monitoring of mass and viscoelastic properties, (3) scanning spectroscopic analysis, and (4) spectroscopic imaging of a coiled polymeric array.
Bayer Symposium on High‐Throughput Experimentation in Materials Research and Process Optimization
Authors: Rothbarth Frank
Published: February 2003

This section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de.
Combinatorial Methods, Automated Synthesis and High‐Throughput Screening in Polymer Research: Past and Present
Authors: Hoogenboom Richard , Meier Michael A. R. , Schubert Ulrich S.
Published: February 2003

Combinatorial techniques, parallel experimentation and high‐throughput methods represent a very promising approach in order to speed up the preparation and investigation of new polymeric materials: a large variety of parameters can be screened simultaneously resulting in new structure/property relationships. The field of polymer research seems to be perfectly suited for parallel and combinatorial methods due to the fact that many parameters can be varied during synthesis, processing, blending as well as compounding. In addition, numerous important parameters have to be investigated, such as molecular weight, polydispersity, viscosity, hardness, stiffness and other application‐specific properties. A number of corresponding high‐throughput techniques have been developed in the last few years and their introduction into the commercial market further boosted the development. These combinatorial approaches can reduce the time‐to‐market for new polymeric materials drastically compared to traditional approaches and allow a much more detailed understanding of polymers from the macroscopic to the nanoscopic scale. Here we provide an overview of the present status of combinatorial and parallel polymer synthesis and high‐throughput screening.

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High‐Output Polymer Screening: Exploiting Combinatorial Chemistry and Data Mining Tools in Catalyst and Polymer Development
Authors: Tuchbreiter Arno , Marquardt Jürgen , Kappler Bernd , Honerkamp Josef , Kristen Marc O. , Mülhaupt Rolf
Published: February 2003

High‐output polymer screening (HOPS) combines automated polymerization with online reaction monitoring, rapid polymer characterization and novel fingerprint technology useful in polymer preparation as well as polymer processing and polymer additive development. Originally, HOPS was introduced to develop polymerization catalysts and polyolefin materials more effectively. In comparison to conventional high‐throughput screening, focusing on ultrahigh speed of catalyst screening using arrays of miniaturized reactors, output‐oriented, process‐relevant HOPS is aiming at generating and exploiting high information density (useful information/experiment). Catalyst systems for olefin polymerization are evaluated in automated workstations with multiparallel as well as semi‐ and fully automated, upgraded lab reactors. Automated polymerizations under standardized conditions afford large families of well‐characterized polymers which serve as calibration samples for data analysis. Data analysis, using multivariate calibration, is the key to basic correlations between spectroscopic information and catalyst and polymer properties as well as reaction parameters and processing conditions. IR spectroscopic fingerprints are used to measure chemical copolymer composition, density, molecular weight as well as thermal and even mechanical properties. This fingerprint technology can be applied in online quality control and facilitates transfer from lab results into pilot and production plants. Fingerprint methods are important components of rapid online analysis and can reduce the need for time‐ and money‐consuming polymer testing.

Fingerprint technology combines spectroscopic analysis by means of “cheap” spectrometers with multivariate calibration.

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Fingerprint technology combines spectroscopic analysis by means of “cheap” spectrometers with multivariate calibration.
R&D Intensification in Polymer Catalyst and Product Development by Using High‐Throughput Experimentation and Simulation
Authors: Gruter Gert‐Jan M. , Graham Alasdair , McKay Ben , Gilardoni François
Published: February 2003

Currently laboratory automation is a rapidly growing field of interest in chemical process research and development. The idea of using automated and parallel methods for the optimization of chemical processes was initiated by the extensive implementation of combinatorial techniques in medicinal chemistry. The techniques applied involve all methods and concepts aimed at dramatically increasing the output of research by extensive use of automation, parallelization and miniaturization, fast analysis, advanced data handling and by efficient automated planning, scheduling and tracking. In this paper, the “Combi” or high‐throughput experimentation approach consists of the integration of parallel experimentation with four key modeling and simulation methodologies, modeling, multivariate statistics, statistical design of experimentation and empirical model generation.

Integrated automated liquid and solid handling.

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Integrated automated liquid and solid handling.
Automated Parallel Synthesis of MADIX (Co)Polymers
Authors: Chapon Pascal , Mignaud Catherine , Lizarraga Gilda , Destarac Mathias
Published: February 2003

An automated parallel synthetic approach has been developed for synthesizing polymer libraries by the Macromolecular Design via the Interchange of Xanthates (MADIX) process. The experimental set‐up, parallel polymerizations, characterization, and reproducibility tests are detailed. Examples of acrylic diblock copolymers synthesized in this way are given.

Automated MADIX polymerizations of BA in the presence of a X1‐capped PEA.

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Automated MADIX polymerizations of BA in the presence of a X1‐capped PEA.
Automated Parallel Temperature Optimization and Determination of Activation Energy for the Living Cationic Polymerization of 2‐Ethyl‐2‐oxazoline
Authors: Hoogenboom Richard , Fijten Martin W. M. , Brändli Christof , Schroer Josef , Schubert Ulrich S.
Published: February 2003

Sixteen parallel polymerization reactions of 2‐ethyl‐2‐oxazoline have been performed at different temperatures in an automated synthesizer that allowed individual heating of each reactor. During the reactions samples were taken automatically, which were characterized by means of both online GPC and offline GC, in order to optimize the reaction temperature and to determine the activation energy of the polymerization.

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Instrumentation for Combinatorial and High‐Throughput Polymer Research: A Short Overview
Authors: Schmatloch Stefan , Meier Michael A. R. , Schubert Ulrich S.
Published: February 2003

Starting in biochemistry and pharmaceutical chemistry, combinatorial methods, automated synthesis and high‐throughput characterization are being further developed for organic synthesis and polymer research. The development is strongly driven by the achievements in biochemistry and pharmaceutical chemistry and the need to minimize the time‐to‐market for novel polymeric products. The success of high‐throughput methodologies in polymer science is partially limited by the commercially available hardware (synthesizers, workstations, robots, online‐characterization instruments, etc.) and software. A short overview of commercially available equipment for polymer research is provided in this Review.

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Combinatorial Materials Research in the Polymer Industry: Speed versus Flexibility
Authors: Iden Ruediger , Schrof Wolfgang , Hadeler Joachim , Lehmann Stephan
Published: February 2003

With combinatorial materials research (CMR), a new research approach toward the development and optimization of materials has been established at BASF. While adopting the basic ideas of combinatorial chemistry, CMR faces a whole bunch of challenges throughout the entire combinatorial process loop. New concepts for sample preparation on a smaller scale, i.e. synthesis and formulation, for parallel or fast sequential screening and characterization, and for appropriate management of yet unknown amounts of data have been developed. The integration of as many as possible workflow steps and the interplay of experts from various relevant fields, such as chemistry, engineering, robotics, informatics, and physics, are necessary. First results in the fields of polymer synthesis and coatings formulation give an impression of the innovative power and efficiency of this new kind of research.

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