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  • Polymer and Materials Science  (1,164)
  • 1995-1999  (1,164)
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  • 11
    Electronic Resource
    Electronic Resource
    LC multiblock copolymers containing polysulfone segments. I. Synthesis and morphology (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1819-1833 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Multiblock copolymers offer the possibility to combine the properties of different polymers. Thus, new materials with tailor-made unique properties are available by coupling of different suitable polymeric segments. The goal of the work discussed in this paper was to combine advantageous properties of liquid-crystalline polymers (LCP) with those of polysulfone (PSU). Therefore, liquid crystalline poly(ethylene terephthalate-co-1,4-oxybenzoates) were connected with PSU oligomers. Chemically homogeneous multiblock copolymers with high molecular weight were obtained by a melt transesterification procedure. It was demonstrated by wide angle x-ray scattering (WAXS), polarizing microscopy, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) that the properties of the multiblock copolymers (solid phase structure, phase behavior, morphology, glass transition, and melting behavior) can be balanced by the segment length of the incorporated blocks. The investigations clearly reveal the existence of a two-phase structure. However, a change of properties compared to the corresponding homopolymers refers to certain interactions between the phase due to the chemical connection of the LCP and PSU segments. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Relationship between morphology and glass transition temperature in solvent-crystallized poly(aryl ether ketones) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 65-73 
    Details
    ISSN: 0887-6266
    Keywords: poly(ether ether ketone) (PEEK) ; poly(ether ketone ketone) (PEKK) ; solvent-induced crystallization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relationship between semicrystalline morphology and glass transition temperature has been investigated for solvent-crystallized poly(ether ether ketone) (PEEK) and poly(ether ketone ketone) (PEKK). Solvent-crystallized specimens of both PEEK and PEKK displayed a sizeable positive offset in Tg compared to quenched amorphous specimens as well as thermally crystallized specimens of comparable bulk crystallinity; the offset in Tg for the crystallized samples reflected the degree of constraint imposed on the amorphous segments by the crystallites. Small-angle X-ray scattering studies revealed markedly smaller crystal long periods (d) for the solvent-crystallized specimens compared to samples prepared by direct cold crystallization. The strong inverse correlation observed between Tg and interlamellar amorphous thickness (lA) based on a simple two-phase model was in excellent agreement with data reported previously for PEEK, and indicated the existence of a unique relationship between glass transition temperature and morphology in these poly(aryl ether ketones) over a wider range of sample preparation history and lamellar structure than was previously reported. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 65-73, 1998
    Additional Material: 3 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Anisotropic ionic conductivity of lithium-doped sulfonated PBI (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2925-2933 
    Details
    ISSN: 0887-6266
    Keywords: ionic conductivity ; DC conductivity ; rigid-rod polymer ; depletion measurement ; X-ray scattering ; anisotropic ; polymer electrolyte ; polyelectrolyte ; conducting polymers ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conductivity study results of lithium-doped sulfonated PBI, a conjugated rigid rod polymer, poly[(1,7-dihydrobenzo[1,2-d:4,5-d′]dimidazole-2,6-diyl)-2-(2-sulfo)-p-phenylene], derivatized with pendants of propane sulfonate Li+ ionomer are reported. The room-temperature DC four-probe conductivity parallel to the surface of cast films was as large as 8.3 × 10-3 S/cm. Similar measurements with an eight-probe configuration showed no difference between bulk and surface conductivity. The ionic nature of the conductivity was indicated by constant voltage depletion experiments and by secondary ion mass spectroscopy measurements of the residues near the electrodes. The DC two-probe conductivity measured transverse to the sample surface was three to four orders of magnitude smaller than longitudinal conductivity, while the AC two-probe conductivity was even less. Electron microscopy indicated that the films had a layered structure parallel to the surfaces. This structural anisotropy was confirmed by refractive index values obtained from wave-guide experiments and by wide angle X-ray scattering. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2925-2933, 1997
    Additional Material: 11 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    3D characterization of a W/TiN/ Ti/Si contact structure using MULSAM (1998)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 461-470 
    Details
    ISSN: 0142-2421
    Keywords: W/TiN/Ti/Si contact structure ; MULSAM ; TEM ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The W/TiN/Ti/Si contact structures needed for ultra-large-scale integrated circuits have been studied using cross-sectional transmission electron microscopy (TEM) and multi-spectral Auger electron microscopy. Access to the Ti/Si interface for chemical characterization using SEM, Auger and electron energy-loss imaging and spectroscopy has been achieved by using a novel method of bevelled polishing of the silicon substrate material. Cross-sectional TEM was used to calibrate the depth scale in the MULSAM image sets, so allowing measurements of the thicknesses of various interfacial layers and the penetration of the ohmic contacts into the silicon. The TiN layer, providing adhesion of the tungsten as well as acting as a diffusion barrier, appears to have a domed shape, which penetrates the tungsten overlayer to a greater extent in the contact centres. The results of this work, combined with earlier, related, studies, enable a three-dimensional characterization of the bottom and sidewall structures in these contacts. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Seven new organic superconductors in the system (ET)2M(CF3)4(solvent) (M = Cu, Ag): effect of solvent replacement**This work was supported by the U. S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences, under contract No. W-31-109-ENG-38. Research at the University of Cologne was supported by the Fonds der Chemischen Industrie and the Ministerium für wissenschaft and Forschung des Landes Nordrhein-Westfalen (Arbeitsge-meinschaft Fluorchemie). We thank Dr. Patricia M. Keane for technical assistance with EDAX studies. M. E. K. and S. A. S. are undergraduate research participants from Hope College (Holland, MI) and Mansfield University (Mansfield, PA) respectively, sponsored by the Argonne Division of Educational Programs. (1995)
    Weinheim : Wiley-Blackwell
    Advanced Materials 7 (1995), S. 634-639 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19950070705
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  • 16
    Electronic Resource
    Electronic Resource
    Synthesis and properties of chelate polymers of Cu(II), Ni(II), Co(II), Mn(II) and Zn(II) with a schiff's base of 5,5′-methylene-bis(3,3′-dinitrosalicylaldehyde) with 1,6-hexanediamine (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 234 (1996), S. 13-20 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird über die Synthese, die Charakterisierung und die Koordinationseigenschaften der im Titel genannten Polymerliganden berichtet. Die polymeren Chelate wurden durch Polykondensation von Übergangsmetallionen (M) mit polymeren Schiffschen Basen (L) hergestellt. Die Analysenergebnisse weisen auf eine Formel (ML)n für die Chelate hin. Die Polychelate sind stabil und unlöslich in gebräuchlichen organischen Lösemitteln. Die geometrische Anordnung der Liganden um das zentrale Metallion wird auf der Basis von Messungen der magnetischen Suszeptibilitäten und UV-Reflexionsspektren beschrieben. Die Ligandenfeldaufspaltungsparameter 10 Dq, der interelektronische Abstoßungsparameter B, der nephelauxetrische Parameter β und die Ligandenfeldaufspaltungsenergien wurden für die Ni(II)- und Co(II)-Chelate berechnet. Alle Chelate sind gegenüber mäßig konzentrierten Säuren und verdiinntem Alkali bei Umgebungstemperaturen bestandig und zeigen unterschiedliche thermische Stabilität. IR-Spektren zufolge ist der Ligand in der Regel über die Carbonylsauerstoffatome (C=O) und die phenolischen OH-Gruppen unter Austausch der Wasserstoffionen durch die Metallionen koordiniert.
    Notes: The synthesis, characterization and coordination aspects of the title polymer ligands are reported. The polymeric chelates were prepared by polycondensations of transition metal ions (M) with a poly(Schiff's base) (L). The analytical data propose a (ML)n formula for the chelates. All the polychelates are stable and insoluble in common organic solvents. The geometry around the central metal ion in each chelate is proposed on the basis of measurements of magnetic susceptibilities and UV reflectance spectra. The ligand field splitting parameters 10 Dq, the interelectronic repulsion parameter B, the nephelauxetric parameter β and ligand field splitting energies (L.F.S.E.) have been calculated for Ni(II) and Co(II) chelates. All chelates are resistant to moderately concentrated acids and dilute alkalies at ambient temperature. They exhibit thermal stabilities to varying degrees. IR spectra show that the ligand usually coordinates via the carbonyl oxygen (C=O) and the phenolic OH with replacement of hydrogen by metal ions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052340102
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  • 17
    Electronic Resource
    Electronic Resource
    Effect of ageing on the dielectric behaviour of silicone-EPDM blends (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 225 (1995), S. 21-35 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Dielektrische Messungen an Silikon, EPDM und einem Blend aus gleichen Gewichtsteilen beider Polymerer wurden im Frequenzbereich 1-105 Hz zwischen 25 und 200°C vor und nach Alterung in Wasser, Wasserdampf und Luft durchgeführt. Für das unpolare und nahezu verlustfreie EPDM werden niedrige Werte der Dielektrizitätskonstante und des Verlustfaktors gemessen. Die für EPDM beobachtete thermische Depolarisation ist bei in Luft gealtertem EPDM aufgrund von Dipolorientierung etwas ausgeprägter. Silikon wird in zwei Stufen polarisiert. Veränderungen der dielektrischen Eigenschaften und des spezifischen Gleichstromwiderstands nach Alterung belegen, daß Ladungsträger bei niedriger Temperatur und polare Silanolgruppen bei hoher Temperatur zur Polarisation beitragen. Die Eigenschaften des Blends hängen vom Alte-rungsmedium ab. Hydrothermische Alterung bewirkt eine qualitative Verbesserung des Dielektrikums Silikon durch Entfernung von Ladungsträgern und der Unterdrückung der Silikonhydrolyse durch EPDM. Durch Alterung des Blends in Luft nimmt dessen Polarisation zu, bedingt durch die Bildung von Ladungsträgern und Dipolen sowie die zusätzliche Grenzchicht. Aus Aktivierungsenergien wird gefolgert, daß die bei niedriger Temperatur stattfindende Polarisation mit der Beweglichkeit der Ladungsträger und der Orientierung von Seitengruppen zusammenhängt. rungsmedium ab. Hydrothermische Alterung bewirkt eine qualitative Verbesserung des Dielektrikums Silikon durch Entfernung von Ladungsträgern und der Unterdrückung der Silikonhydrolyse durch EPDM. Durch Alterung des Blends in Luft nimmt dessen Polarisation zu, bedingt durch die Bildung von Ladungsträgern und Dipolen sowie die zusätzliche Grenzchicht. Aus Aktivierungsenergien wird gefolgert, daß die bei niedriger Temperatur stattfindende Polarisation mit der Beweglichkeit der Ladungsträger und der Orientierung von Seitengruppen zusammenhängt.
    Notes: Dielectric measurements in the frequency (1-105 Hz) and temperature (25-200°C) domains have been carried out for silicone, EPDM, and their 50/50 (by weight) blend before and after ageing in water, steam and air. Low values of permittivity and loss tangent for EPDM reflect its non-polar and loss-free nature. Thermal depolarisation is also observed with EPDM and the air-aged specimen shows little rising trend due to dipole orientation. Silicone is found to be polarised in two steps. Changes in dielectric properties and DC resistivity on hydrothermal weathering and air ageing confirms that charge carriers contribute in the low-temperature step and polar silanol groups contribute in the high-temperature region. The properties of the 50:50 blend are very much sensitive to the medium of ageing. Hydrothermal ageing improves the quality of the dielectric of silicone due to removal of charge carriers and the suppression of silicone hydrolysis by EPDM. Ageing of the blend in air increases the polarisation to a very high level owing to the charge carriers, the additional interface and the dipoles formed during ageing. Activation energies suggest that the low temperature polarisation step is associated with charge carrier mobility and orientation of pendent groups.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052250103
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  • 18
    Electronic Resource
    Electronic Resource
    Polymeric prodrugs. Synthesis, release study and antimicrobial properties of polymer-bound acriflavine (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 1-8 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(methylmethacrylat-co-maleinsäureanhydrid)-Matrices mit variierendem Gehalt an oberflächenfunktionellen Anhydridgruppen wurden mittels Lösungspolymerisation hergestellt und charakterisiert. Acriflavin wurde in organischem Medium chemisch auf der Matrix-Oberfläche fixiert. Der an die Matrix gebundene Acriflavin-Anteil wurde spektroskopisch bestimmt, und die Freisetzungsgeschwindigkeit des Acriflavins in schwachem basischem Medium wurde in Verbindung mit der antimikrobiellen Aktivität in vitro ermittelt.
    Notes: A matrix of poly(methyl methacrylate-co-maleic anhydride) with surface containing functional anhydride groups of different percentage was prepared by solution polymerization and characterized. Acriflavine was bound on the surface of this matrix by chemical bonding in organic medium. The amount of acriflavine chemically bound to the matrix was spectroscopically characterized and the in vitro release rate of acriflavine in weakly basic medium was established along with the determination of its antimicrobial activity.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450101
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  • 19
    Electronic Resource
    Electronic Resource
    Direct observation of a diblock copolymer-induced microemulsion at a polymer/polymer interface (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2351-2357 
    Details
    ISSN: 0887-6266
    Keywords: segregation ; interfacial tension ; polymer microemulsion ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We have studied the segregation of a block copolymer of poly(d8-styrene-b-2-vinylpyridine) (dPS-PVP) at the interface between polystyrene and a random copolymer of poly(styreneran-4-hydroxystyrene) (PS-r-PPHS). Forward recoil spectrometry (FRES) was used to measure the equilibrium excess (z*) of the dPS-PVP chains at the interface as a function of its volume fraction in the bulk PS phase (φ∞). It was found that there is a sharp increase in z* at a critical value of φ∞. This upturn indicates the formation of a microemulsion of PS and the random copolymer PS-r-PPHS due to a vanishing of the interfacial tension caused by the strong adsorption of the block copolymer. Cross-sectional transmission electron microscopy (TEM) of the interface shows that this microemulsion starts to form at the interface by forming a deeply corrugated structure where the “wavelength” of the corrugations is of the order of 50 nm. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331706
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  • 20
    Electronic Resource
    Electronic Resource
    Proton motion of poly(γ-benzyl L-glutamate) in benzyl alcohol during gelation as measured by quasielastic neutron scattering (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 649-656 
    Details
    ISSN: 0887-6266
    Keywords: liquid crystalline polymer ; quasielastic neutron scattering ; gelation ; rotational dynamics ; poly(γ-benzyl L-glutamate) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Quasielastic neutron scattering has been used to study the motion of protons in two solutions of poly(γ-benzyl L-glutamate) (PBLG) and deuterated benzyl alcohol (DBA) as they are brought from the high temperature (cholesteric and isotropic) phase towards the gel. Quasielastic neutron scattering results demonstrate that, in both the isotropic and cholesteric phases, the local rotational dynamics of the polymer are continuous in the high temperature phases, but become more constrained as the system approaches and enters the gel phase. The results also show that the energetics of the rotational motion of the protons below the gelation threshold are independent of the initial phase and the protons are not rendered immobile in the gel phase. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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