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  • 1
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: This paper reports results of the second SIMS round-robin study on GaAs impurity analysis in which 16 laboratories participated. Three different types of SIMS instruments, including Cameca IMS-3F or IMS-4F, Atomika ADIDA-3000 and Hitachi IMA-3, were used for this study. The specimens were cut from identical multielement-doped GaAs crystals and distributed as common standards for the quantitative impurity analyses. The interlaboratory deviations in quatitative results based on the common standards were found to be 10-20%, except for some low-concentration specimens and the results for zinc. This was approximately half of the corresponding results produced from standard specimens provided by the laboratories themselves. The interlaboratory deviations of relative ion intensity between impurity and matrix were 〈50% for those laboratories employing instruments of the same type, except for low-concentration specimens. These results show that quantitative analysis to an accuracy of 50% can be performed without standard specimens by utilizing relative sensitivity factors for each type of instrument.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2157-2163 
    ISSN: 0887-624X
    Keywords: reactive polyester ; pendant carboxyl group ; chemoselective polycondensation ; polymer catalyst ; polymer reaction ; bifunctional catalytic mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic polyester, copolyester, and poly(ester-amide-thioester) having pendant carboxyl groups are directly synthesized by the organic phase/water phase interfacial polyconden-sation using low-molecular and polymeric phase transfer catalysts. Spectral analysis of the resulting polymers indicates that the nucleophilicity of salts of phenols to diacid chloride is far higher than that of salts of carboxylic acids and chemoselective esterification occurs in a 100% yield. Even if the polymeric catalyst having amino acid moiety as a nucleophilic group is used in the polycondensation, the polymers do not contain anhydride groups. The polyester can be almost quantitatively converted to polymers with different reactive groups by reacting the pendant carboxyl groups with alkyl halides in a DMAc-H2O mixture con-taining K2CO3. A bifunctional catalytic mechanism is proposed for the chemical modification of the polyesters. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2657-2665 
    ISSN: 0887-624X
    Keywords: amphiphilic rubber ; butyl rubber ; saccharide ; microphase-separated structure ; thermoplastic elastomer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new type of amphiphilic elastomer was synthesized, which consisted of butyl rubber and a D-maltose derivative as a backbone and side groups, respectively. The synthesis was accomplished by the sequence of the three following reactions: (1) Hydroxyl groups of D-maltonolactone were protected by a trimethylsilyl group. (2) The resulting maltonolactone derivative was subjected to a reaction with chemically modified butyl rubber having pendant amino groups. (3) The protecting trimethylsilyl groups on the maltose residues were removed by treating with tetra-n-butylammonium fluoride. This new amphiphilic elastomer behaved as a thermoplastic elastomer and showed good mechanical properties. The saccharide seg-ments aggregated in the hydrophobic butyl rubber matrix to form a microphase-separated structure, as confirmed by differential scanning calorimetry, transmission electron mi-croscopy, small-angle x-ray scattering, and dynamic mechanical measurements. The ag-gregated saccharide domains are estimated to function both as crosslinking sites and rein-forcing fillers in the rubber matrix. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3359-3363 
    ISSN: 0887-624X
    Keywords: hydrazinodeoxycellulose ; adsorption ; heavy metal ions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nitrogen-containing cellulose derivatives hydrazinodeoxycellulose (HDC) and carboxyalkyl hydrazinodeoxycelluloses (α- and β-CAHDCs) were prepared from 6-chlorodeoxycellulose (CDC). Their adsorption of divalent transition metal ions was determined from dilute aqueous solutions and compared with that of aminoalkyl celluloses (AmACs) reported previously. HDC scarcely adsorbs metal ions in the pH range of 1-2, whereas α- and β-CAHDCs adsorb metal ions in this pH range. However, the adsorption of metal ions on HDC increases rapidly with increasing pH and HDC more effectively adsorbs metal ions than α- and β-CAHDCs in weakly acidic conditions. The ability to adsorb Cu2+ ions was in the order of AmAC (carbon number in the diamine moiety m = 2) 〉 HDC 〉 α-CAHDC 〉 β-CAHDC in the weakly acidic region. These adsorbents selectively adsorb Cu2+ ions from the solutions containing other metal ions such as Mn2+, Co2+, and Ni2+, and the Irving-Williams series is obeyed in these adsorbent/metal ion systems. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3359-3363, 1997
    Additional Material: 3 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 25 (1987), S. 495-501 
    ISSN: 0887-6258
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 911-923 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three commercial heparins of different molecular weights and anticoagulant activities were dinitrophenylated (DNP) with 2,4-dinitrofluorobenzene under aqueous conditions. The absorption spectra observed for DNP heparins in a 1% NaHCO3 solution consisted of the two absorption spectra characteristic of DNP - amino (N - DNP) and DNP - hydroxyl (O - DNP) groups. The number of N - DNP, O - DNP, and (N + O) - DNP groups were determined as well as the number of N - DNP groups per heparin chain; different values (i.e., 0.16, 0.17, and 0.55) for the latter were obtained with the three heparins. Further calculations showed that two of the heparins had approximately two (N + O) - DNP groups per chain (i.e., 2.1 and 1.8) whilst the third sample, considered to be a “cruder” heparin, had a value of 1.4.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 1853-1862 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diacetylenes substituted with various amide groups were prepared and their solid-state polymerization behavior was studied. A calorimetric study of the isothermal polymerization of 1,6-diacetylamino-2,4-hexadiyne was performed in detail. This compound has an extremely high reactivity. The reaction proceeded very quickly and the ultimate conversion reached over 40% slightly above room temperature. The feature of the reaction resembles those observed in the solid-state polymerization of other diacetylene compounds, i.e., the reaction proceeds slowly in the initial stage, but the rate of reaction increases drastically at about 5% conversion to polymer. Quantitative conversion, however, was not attained at any temperature, and the reaction leveled off within 1.5 h. It is assumed that the reaction cannot continue owing to the distortions generated in the crystals during the polymerization process. The crystalline state of the polymer obtained was highly disordered.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 4431-4437 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1161-1170 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymers of p-(phenylazo)benzyl-L-aspartate and n-octadecyl-L-aspartate exist as right- and left-handed α-helices in solution at 25°C depending on the copolymer composition: the reversal of helix sense from a right- to left-handed one occurs with increasing the azobenzene content. The α-helices of the copolymers are very sensitive to trifluoroacetic acid (TFA), and are converted into random coil below 2.0% of TFA. Among the copolymers, the copolymer containing 47% azobenzene groups is unique since it exhibits a TFA-induced conformational change from right-handed α-helix to random coil via left-handed α-helix. Upon UV light irradiation at 25°C, the copolymers containing 68 and 89% azobenzene groups caused the reversal in helix sense from a left- to right-handed one. The conformations of the copolymers were dependent on temperature, mostly right-handed and left-handed α-helices at lower and higher temperatures, respectively. On this basis, the copolymer containing 47% azobenzene groups could be made to undergo a photoinduced helix reversal at high temperatures.
    Additional Material: 7 Ill.
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  • 10
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of fluorine-containing homopolycarbonate and copolycarbonates with a wide range of unit ratio were synthesized by the two-phase phase-transfer-catalyzed plycondensation of 2,2-bis (4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (Bisphenol AF) and/or 2,2-bis (4-hydroxy-phenyl) propane (Bisphenol A) with trichloromethyl chloroformate, and the effect of the fluorine substitution on the synthesis and properties of these polymers was investigated by comparing with those of Bishphenol A-based homopolycarbonate without fluorine. Film-forming moderate-to high-molecular-weight fluorine-containing polycarbonates with reduced viscosities up to 0.54 dL/g were obtained in high yields by using tetra-n-butylammonium bromide as a catalyst, sodium hydroxide as a base, and 1,2-dichloroethane as a medium. The reduced viscosity, however, decreased markedly with increasing feed ratio of Bisphenol AF. Their solubility in common organic solvents was clearly improved by the introduction of fluorine atom. The pliability of the films also increased remarkably with increasing fluorine content. The contact angles formed by water were larger than 90°, regardless of their fluorine contents, at 25°C in air. The critical surface tension and refractive index of Bisphenol AF-based homopolycarbonate were ca. 20 dyn/cm and 1.426, respectively. The glass transition temperatures and thermal stability increased monotonously with increasing fluorine content.
    Additional Material: 2 Ill.
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