bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Synthesis of Controlled Poly(styrene‐co‐acrylic acid)s of Various Compositions by Nitroxide‐Mediated Random Copolymerization
Authors: Couvreur Laurence , Charleux Bernadette , Guerret Olivier , Magnet Stéphanie 
Published: November 2003

AbstractStyrene and acrylic acid were copolymerized under controlled conditions, in 1,4‐dioxane solution at 120 °C and 2 bar, using an alkoxyamine initiator based on the N‐tert‐butyl‐N‐(1‐diethylphosphono‐2,2‐dimethylpropyl) nitroxide, SG1. A broad composition range from 90/10 to 10/90 was investigated. With slightly different initiator concentrations and a similar initial proportion of free SG1 (4.5 mol‐% with respect to the initiator) the polymerizations exhibited very similar rates, irrespective of the proportion of acrylic acid in the comonomer mixture (80% conversion within 8 h). In all cases, the copolymers presented number average molar masses, $\overline M _{\rm n}$, that increased linearly with overall monomer conversion, and polydispersity indexes that ranged between 1.2 and 1.4. Moreover, $\overline M _{\rm n}$ followed the calculated values, based on the initial concentrations of monomers and initiator. The variation in the initiator concentration allowed to target various molar masses, but some limitation appeared at low initiator concentration owing to chain transfer to 1,4‐dioxane. From the kinetic data, the reactivity ratios were determined: rA = 0.27 ± 0.07 for acrylic acid and rS = 0.72 ± 0.04 for styrene. Depending on the initial comonomer composition, chains exhibited no or small composition drift, and hence a slightly pronounced gradient structure.Reactivity ratios for acrylic acid and styrene.magnified imageReactivity ratios for acrylic acid and styrene.
Radical Cation, Dimer Radical Cation and Neutral Radical of 2,3‐Dihydropyran – Possible Initiators of its Polymerisation?
Authors: Naumov Sergej , Janovský Igor , Knolle Wolfgang , Mehnert Reiner 
Published: November 2003

AbstractThe radical cation, distonic dimer radical cation, and radical of 2,3‐dihydropyran (DHP), which may play an important role in mechanism of radical polymerisations of DHP, were radiolytically generated at low temperatures in freon matrices and investigated by electron paramagnetic resonance (EPR) spectroscopy, as well as by quantum chemical methods. DHP radical cation with a half‐chair conformation and six coupling protons (0.88, 0.18, 4.60, 1.88, 1.27, 0.56 mT) was found to be stable in CF3CCl3 between 77 and 145 K. The same radical cation was observed at 77 K also in CF2ClCFCl2, but on increasing temperature, transformation into the neutral 4‐dihydropyryl radical occurred; the latter also shows the half‐chair conformation at 140 K and is characterised by six coupling protons (0.14, 2.31, 0.92, 1.42, 0.28, 1.35 mT). At a high DHP concentration in CF2ClCFCl2 a distonic DHP dimer radical cation, with strongly separated spin and charge and only two coupling protons (1.8 and 3.2 mT) was identified at 100 K, also yielding, at higher temperatures, the 4‐dihydropyryl radical.The radiolytically generated species from DHP and their observed EPR spectra.magnified imageThe radiolytically generated species from DHP and their observed EPR spectra.
Block Copolymers of Methyl Vinyl Ether and Isobutyl Vinyl Ether With Thermo‐Adjustable Amphiphilic Properties
Authors: Verdonck Beatrice , Goethals Eric J. , Du Prez Filip E. 
Published: November 2003

AbstractThe thermo‐adjustable hydrophilic/hydrophobic properties of AB, ABA and BAB block copolymers in which A is poly(methyl vinyl ether) (PMVE) and B is poly(isobutyl vinyl ether) (PIBVE) have been investigated. The block copolymers were prepared by “living” cationic polymerization using sequential addition of monomers. The polymerizations were carried out with the system acetal/trimethylsilyl iodide as initiator and ZnI2 as activator. The initiating system based on diethoxyethane leads to AB block copolymers whereas the initiating system based on tetramethoxypropane leads to ABA or BAB triblock copolymers. Well‐defined block copolymers of different composition with controlled molecular weights up to approx. 10 000 have been prepared. When IBVE is added to living PMVE, PIBVE‐blocks form only in the presence of an additional amount of ZnI2, which is attributed to the fact that part of the ZnI2 is inactive because of complex formation with PMVE. At room temperature, the combination of hydrophilic (PMVE) and hydrophobic (PIBVE) segments provides the copolymers with surfactant properties. Above the lower critical solution temperature (LCST) of PMVE, situated around 36 °C, the PMVE‐blocks become hydrophobic and the amphiphilic nature of the block copolymers is lost. The corresponding changes in hydrophilic/hydrophobic balance have been evaluated by investigation of the emulsifying properties of the block copolymers for water/decane mixtures as a function of the temperature. Below the LCST, the block copolymers have emulsifying properties similar to or better than those of the commercial PEO‐PPO block copolymers (Pluronic®). Either oil‐in‐water or water‐in‐oil emulsions can be obtained, depending on the polymer architecture and the water/decane volume ratio. The emulsifying properties are strongly reduced or completely lost above 40 °C. Emulsions obtained with a PMVE36‐b‐PIBVE54 block copolymer for a water/decane (v/v) ratio of 85/15 remained stable for more than six months.50/50 and a 85/15 water/decane w/o emulsion (15 g/l) with the PMVE36‐b‐PIBVE54 block copolymer at 20 °C.magnified image50/50 and a 85/15 water/decane w/o emulsion (15 g/l) with the PMVE36‐b‐PIBVE54 block copolymer at 20 °C.
Synchrotron X‐ray and DSC Studies of the Phase Behaviour of Poly(diethylene glycol p,p′‐bibenzoate)
Authors: Pérez Ernesto , Benavente Rosario , Cerrada María L. , Bello Antonio , Pereña José M. 
Published: November 2003

AbstractTime‐resolved synchrotron X‐ray and DSC experiments were applied to investigate the phase behaviour of poly(diethylene glycol p,p′‐bibenzoate), PDEB. The DSC results are indicative of the formation of a smectic mesophase, previously identified as a SmCA type, which can be easily quenched down to room temperature. However, the synchrotron results show that the SmCA phase undergoes some kind of ordering or transformation at temperatures below 110 °C. Moreover, the annealing of PDEB at temperatures above Tg for sufficiently long times leads to the formation of a highly ordered structure, although very thin crystals and low crystallinities are obtained.Scattering profiles corresponding to sample PDEB85 in a melting experiment.magnified imageScattering profiles corresponding to sample PDEB85 in a melting experiment.
Side‐chain Cholesteric Liquid Crystalline Elastomers Derived from Nematic Bis‐olefinic Crosslinking Units
Authors: Zhang Bao‐Yan , Hu Jian‐She , Jia Ying‐Gang , Du Bing‐Guang 
Published: November 2003

AbstractThe synthesis of the nematic crosslinking agent (4′‐allyloxy‐benzoyl)‐(4″‐undec‐10‐en‐1‐oyl‐benzoyl)‐p‐benzenediolate (M‐1), the cholesteric monomer cholesteryl undec‐10‐en‐1‐oate (M‐2) and side‐chain cholesteric liquid crystalline elastomers is described. The chemical structures of the obtained monomers and elastomers were confirmed by FTIR and 1H NMR spectroscopy. Their mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the crosslinking M‐1 units on phase behavior of different elastomers prepared by a one‐step hydrosilation reaction was discussed. The elastomers containing less than 20 mol‐% of the crosslinking M‐1 units showed elasticity, reversible phase transition and cholesteric texture. The experimental results demonstrated that the glass transition temperatures and isotropization temperatures of P‐2 ∼ P‐6 increased with increasing the concentration of crosslinking M‐1 units.Synthesis and schematic representation of elastomers.magnified imageSynthesis and schematic representation of elastomers.
Phase Behavior of Poly(methyl methacrylate)/Poly(vinylidene fluoride) Blends in the Presence of High‐Pressure Carbon Dioxide
Authors: Walker Teri A. , Melnichenko Yuri B. , Wignall George D. , Lin J. S. , Spontak Richard J. 
Published: November 2003

AbstractPrevious efforts have demonstrated that high‐pressure CO2 can markedly influence the phase behavior of amorphous polymer blends. In this work, we examine the effect of high‐pressure CO2 on the miscibility of blends composed of glassy poly(methyl methacrylate) (PMMA) and semicrystalline poly(vinylidene fluoride) (PVDF). Blends of this type are known to exhibit lower critical solution temperature (LCST) behavior with partial miscibility up to ≈50–60 wt.‐% PVDF at ambient conditions. Two miscible PMMA/PVDF blends have been systematically exposed to high‐pressure CO2 at 35 °C and pressures below and above the critical pressure. Small‐angle X‐ray scattering reveals that the scattering intensity at high scattering angles shows little dependence on pressure at low CO2 pressures, but increases substantially at relatively high CO2 pressures. Transmission electron microscopy and differential scanning calorimetry analyses confirm that the blends are initially quasi‐homogeneous with diffuse PVDF‐rich dispersions and a single glass transition temperature. After exposure to relatively high CO2 pressures, however, the PVDF is found to crystallize within the PMMA‐rich matrix. Thermal recycling of these blends promotes homogenization, indicating that such CO2‐altered phase behavior is reversible.SAXS patterns acquired from the 69/31 w/w PMMA/PVDF blend.magnified imageSAXS patterns acquired from the 69/31 w/w PMMA/PVDF blend.
Morphology Evolution during the Phase Separation of Polyetherimide/Epoxy Blends
Authors: Gan Wenjun , Yu Yingfeng , Wang Minghai , Tao Qingsheng , Li Shanjun 
Published: November 2003

AbstractThe results of time‐resolved light scattering for the phase separation of epoxy/polyetherimide/anhydride blends show that the evolution of scattering vector qm follows a Maxwell‐type relaxation equation. The relaxation time may be suggested as the time taken for the diffusion of the epoxy‐anhydride n‐mers from the PEI‐rich phase by their relaxation movement, and the apparent activation energy of the relaxation movement is obtained.Values of qm versus time at different temperatures.magnified imageValues of qm versus time at different temperatures.
Polymerization of Vinyl Ethers by (α‐diimine)NiII/Methylaluminoxane Catalysts
Authors: Kim Il , Ha Yun Sun , Ha Chang‐Sik 
Published: November 2003

AbstractPolymerizations of vinyl ethers are carried out with (α‐diimine)nickel(II) catalysts in the presence of methylaluminoxane. Effects of structural variations of the ligand on the activities of catalysts and polymer microstructure are described. The catalysts prepared by changing the bulkiness of ligand substituents in the ortho aryl position result in no specific trends terms of the yield and molecular weight of polymer. Poly(vinyl ether)s are atactic regardless of the structure of the catalyst used.
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Tartaric Acid Starch Ether: A Novel Biopolymer‐Based Polyelectrolyte
Authors: Grote Carsten , Lazik Waldemar , Heinze Thomas 
Published: November 2003

AbstractNew tartaric acid starch ethers have been synthesized applying starch sources of different amylose content. The reactions were carried out heterogeneously in ethanol/water mixtures with cis‐disodiumepoxysuccinate as etherifying reagent leading to products of a degree of substitution (DS) up to 0.3. The molecular structure of the new starch ethers was evaluated by elemental analysis, FTIR and 13C NMR spectroscopy. Preliminary studies using a convenient titration method indicate a high binding capacity for Ca2+ ions which is dependent on the starch source and DS.Tartaric acid starch ethers.magnified imageTartaric acid starch ethers.
2020 foresight: What the HR world may look like then
Authors: Beaumont Richard A. 
Published: November 2003

AbstractLooking back, one can laboriously trace how a current event or situation happened. Looking forward, however,
it is never so easy to discern trends out of current events, and correctly guess where they may lead. This
article is a well‐informed leap ahead to the year 2020 by an HR leader and innovator who looks backward
from there to imagine the direction that many current trends in the human resource management of major companies
may have taken, as a result of their own and societal actions. © 2003 Wiley Periodicals,
Inc.
Goalsharing plan helps Stillwater Mining Company through tough times
Authors: Stark John , Dalton Glenn L. , Carroll Donncha 
Published: November 2003

AbstractWhen the market price of its palladium skyrocketed to an unsustainable high, Stillwater Mining Company
(SMC) faced a small window of opportunity to put the brakes on escalating operating costs. To do that,
it turned to a goalsharing incentive plan to unify the workforce in focused, committed action. By educating SMC
executives, involving employees—including the union—in plan design, and linking the plan to computer
modeling technology, SMC overcame employee skepticism and avoided the goal‐setting problems that had doomed
its previous attempts at goalsharing arrangements. © 2003 Wiley Periodicals, Inc.
Hillenbrand industries builds leadership capabilities to drive its new business strategy
Authors: McMillen Steve , Luebbe Deborah , Lauber Mindy 
Published: November 2003

AbstractWhen successful Hillenbrand Industries adopted an aggressive new business strategy, it realized it might not
have the leadership capabilities to execute it. It rethought its approach to leadership talent management,
partnered with topnotch vendors, and employed leading‐edge technologies to create integrated systems and
processes for acquiring, developing, and deploying the best talent in its industries. Now, four years later, the
cadre of leaders that has emerged has taken the company to even higher levels of performance © 2003
Wiley Periodicals, Inc.
GMFAC: How a simply successful approach to organizational improvement worked at a large city hospital
Authors: Kopelman Richard E. 
Published: November 2003

AbstractRather than making major training investments in sophisticated methodologies, some organizations may find that
the five basic concepts embodied in the GMFAC framework are all they need to lay the foundation for continuous,
sustainable improvement. For members of a New York City hospital, learning the GMFAC principles in the context of
solving an actual operational problem led to visible, measurable improvements in quality and the confidence to
tackle even bigger problems. © 2003 Wiley Periodicals, Inc.
Valuing the worker
Authors: Batstone David 
Published: November 2003

AbstractIn the wake of corporate scandals that have revealed seemingly unbridled greed and unprincipled management
practices, journalist David Batstone has identified eight principles for deciding whether an organization is as
credible, trustworthy, and soluble as it seems. One of those principles, valuing the worker, is explored here
in detail, along with six compelling stories of companies that have—or have not—made this principle
part of their corporate fabric. © 2003 David Batstone
Stromfluss durch ein Molekül: Molekulare Elektronik
Authors: Weber Heiko B. , Mayor Marcel 
Published: November 2003

AbstractHeute gelingt es, einzelne organische Moleküle mit zwei Goldelektroden zu kontaktieren. Dass es sich wirklich um einzelne Moleküle handelt, zeigt das elektrische Leitverhalten eines solchen Kontakts: Verschiedene Moleküle erzeugen unterschiedliche, aber charakteristische Kennlinien. In Zukunft könnten durch Einsatz geeigneter Moleküle die elektronischen Eigenschaften des Einzelmolekül‐Kontakts maßgeschneidert werden. Amerikanischen Wissenschaftlern gelang bereits die Herstellung von Einzelmolekül‐Feldeffekttransistoren und der Bau eines molekularen Speicherbausteins mit 64 Bit. Bis zur technischen Anwendung ist der Weg allerdings noch weit.
Selbstorganisation in der Nanowelt: Nanostrukturierung
Authors: Teichert Christian 
Published: November 2003

AbstractDie Mikroelekronik steuert auf kleinste Nanostrukturen zu, die heutige lithographische Verfahren nicht mehr erzeugen können. Einen Ausweg bieten Selbstorganisationsprozesse. Mit ihnen sind im Prinzip großflächige Anordnungen von Nanostrukturen auf Silizium‐Wafern erreichbar. Ein Weg ist das heteroepitaktische Aufwachsen von Filmen, deren Kristallgitter vom Silizium abweicht. Ein anderer Weg nutzt aus, dass Ionenstrahlen die Oberflächen ausgeprägt strukturieren können. Beide Wege erlauben es, nur mit einer Materialklasse einen Fülle von Nanostrukturen zu erzeugen. Diese eignen sich für viele Anwendungen: Sie reichen von der Optoelektronik über magnetische Datenspeicher bis zu flächig angeordneten organischen Nanostrukturen.
ANTARES: Neutrino‐Daten aus der Tiefe: Neutrino‐Teleskop im Mittelmeer
Authors: Brunner Jürgen 
Published: November 2003

AbstractANTARES ist ein Teleskop, das Neutrinos von entfernten kosmischen Quellen nachweisen soll. Da Neutrinos kaum mit Materie reagieren, nutzt ANTARES ein großes Wasservolumen im Mittelmeer. Um das Teleskop von störenden Sekundärteilchen zu schützen, die beim Auftreffen der kosmischen Strahlung auf die Atmosphäre entstehen, wird es in 2400 Metern Tiefe installiert. Anfang 2003 passierte ANTARES zwei wichtige Bauetappen, darunter die erfolgreiche Installation eines Prototyp‐Strings mit Photosensoren. 2006 sollte der Ausbau des Detektors abgeschlossen sein.
Klimawandel auf dem Mars: Planetenforschung
Authors: Hauber Ernst 
Published: November 2003

AbstractEs gibt mittlerweile eine bemerkenswerte Übereinstimmung zwischen geomorphologischen Beobachtungen und Vorhersagen über die Stabilität von Bodeneis sowie Klimamodellen des Mars. Letztere weisen darauf hin, dass es auf dem Mars in den letzten Millionen Jahren klimatische Umschwünge gegeben haben könnte. Dabei lagerten sich in höheren und mittleren Breiten mehrere Meter mächtige Schichten aus Eis und Staub ab, die sich später zwischen etwa 30° und 60° nördlicher und südlicher Breite teilweise wieder auflösten. Sollte diese Theorie zutreffen, könnten auch heute noch eishaltige Materialien unter einer isolierenden Schicht aus Staub bis in die Äquatorregionen zu finden sein.
USA weisen zunehmend ausländische Physikstudenten ab
Authors: Bührke Thomas 
Published: November 2003

AbstractIn keinem anderen Land der Erde ist der Anteil ausländischer Studenten im Fach Physik größer als in den USA. Nach den Terroranschlägen vom 11. September werden jedoch zunehmend ausländische Studenten, insbesondere aus China und dem mittleren Osten, abgewiesen — zum Leidwesen der Studenten und der Universitäten.http://www.aip.org/statistics
Der Spion, der die Wärme untersuchte
Authors: Heering Peter 
Published: November 2003

AbstractDer in Massachusetts geborene Benjamin Thompson, der ab 1792 auch den Titel eines Grafen von Rumford führte, ist eine der schillerndsten Figuren der Physikgeschichte. Berühmt wurde er insbesondere wegen seiner Experimente zur Wärmetheorie.http://www.famousamericans.net/benjaminthompsonrumford
Die Welt in DIN A4
Authors: Bührke Thomas 
Published: November 2003

AbstractDer Mensch ist in seinem Vorstellungsvermögen weitgehend auf die sichtbare und erlebbare Umwelt beschränkt. Die Skalen der atomaren Welt sind uns ebenso verschlossen wie die Weiten des Universums. Ein einfaches (Gedanken‐)Experiment erschließt den gesamten Größenbereich jedoch auf erstaunliche Weise.
Preparation and characterization of polypropylene/mesoporous silica nanocomposites with confined polypropylene
Authors: Nakajima Hiroyoshi , Yamada Katsuhiro , Iseki Yuki , Hosoda Satoru , Hanai Ayako , Oumi Yasunori , Teranishi Toshiharu , Sano Tsuneji 
Published: November 2003

AbstractPolypropylene (PP)/Ti‐MCM‐41 nanocomposites were prepared by isospecific propylene polymerization with Ti‐MCM‐41/Al(i‐C4H9)3 catalyst. The cross polarization/magic angle spinning (CP/MAS) 13C NMR spectrum of the composite was similar to that of the conventional isotactic PP, and the decrease in the pore volume of Ti‐MCM‐41 in the nanocomposites, as measured by N2 adsorption, was consistent with the value calculated from the weight loss in the thermogravimetric analysis (TGA) curve; both these facts attest to propylene polymerization within the mesopores of Ti‐MCM‐41. Alkali treatment followed by extraction with o‐dichlorobenzene allows us to extract the confined PP out of the Ti‐MCM‐41 mesopores. Although the PP/Ti‐MCM‐41 nanocomposites do not exhibit a crystalline melting point, the same PP when extracted from the mesopores showed a clear melting point at 154.7 °C; this indicates that the crystallization of PP confined in mesopores is strongly hindered. For the PP polymerized within the confinement, the molecular weight (Mw) and molecular weight distribution (Mw/Mn) were 84,000 and 4.3, respectively; these values were considerably smaller than those of the PP polymerized concurrently outside the Ti‐MCM‐41 mesopores (Mw = 200,000–450,000, Mw/Mn = 40–75). Therefore, the confinement also has a marked effect on the molecular weight of the PP. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3324–3332, 2003
Coagulation method for preparing single‐walled carbon nanotube/poly(methyl methacrylate) composites and their modulus, electrical conductivity, and thermal stability
Authors: Du Fangming , Fischer John E. , Winey Karen I. 
Published: November 2003

AbstractA coagulation method providing a better dispersion of single‐walled carbon nanotubes (SWNTs) in a polymer matrix was used to produce SWNT/poly(methyl methacrylate) (PMMA) composites. Optical microscopy and scanning electron microscopy showed an improved dispersion of SWNTs in the PMMA matrix, a key factor in composite performance. Aligned and unaligned composites were made with purified SWNTs with different SWNT loadings (0.1–7 wt %). Comprehensive testing showed improved elastic modulus, electrical conductivity, and thermal stability with the addition of SWNTs. The electrical conductivity of a 2 wt % SWNT composite decreased significantly (>105) when the SWNTs were aligned, and this result was examined in terms of percolation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3333–3338, 2003
Synthesis and characterization of block copolymer/ceramic precursor nanocomposites based on a polysilazane
Authors: Garcia Carlos B. W. , Lovell Conrad , Curry Chris , Faught Marybeth , Zhang Yuanming , Wiesner Ulrich 
Published: November 2003

AbstractThe amphiphilic block copolymer poly(isoprene‐block‐ethylene oxide) was used as a structure‐directing agent for a polysilazane preceramic polymer commercially known as Ceraset. Two block copolymers of different molecular weights and poly(ethylene oxide) weight fractions with body‐centered cubic sphere and hexagonal cylinder morphologies were used. To both polymers, 50 wt % of the silazane oligomer (Ceraset) was added. The resulting composites were cast into films and characterized by small‐angle X‐ray scattering and transmission electron microscopy. The silazane was chemically compatible with the poly(ethylene oxide) microdomains of the block copolymer, and this resulted in a swelling of those domains. After the cooperative self‐assembly of the block copolymer and Ceraset, for both systems the structure was permanently set in the lamellar morphology by the crosslinking of the silazane oligomer with a radical initiator at 120 °C. These results suggest that the use of block copolymer mesophases may provide a simple and easily controlled pathway for the preparation of various high‐temperature SiCN‐type ceramic mesostructures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3346–3350, 2003