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  • 1
    Electronic Resource
    Electronic Resource
    Chemical Imaging of Phase-Separated Polymer Blends by Fluorescence Microscopy (2000)
    Springer
    Journal of fluorescence 10 (2000), S. 135-135 
    Details
    ISSN: 1573-4994
    Keywords: Fluorescence microscopy ; chemical imaging ; polymer blends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Blends of poly(vinylacetate) (PVAc) and poly(cyclohexylmethacrylate) (PCHMA) labeled by copolymerization with 4-methacryloylamine-4′-nitrostilbene (Sb), with (1-pyrenylmethyl)methacrylate (Py), or with 3-(methacryloylamine)propyl-N-carbazole (Cbz) were prepared by casting dilute solutions in tetrahydrofurane (THF) or chloroform. Films about 10 μm thick were formed. Phase separation in two types of domains is observed by transmission optical microscopy (TOM) and epifluorescence microscopy (EFM): small craters of 1 to 10 μm placed at the polymer-air interface and larger domains, on the scale of 100 μm. The morphology of samples depends on the composition of the polymer blend and on solvent. The green fluorescence of Sb, the violet of Py, or the blue of Cbz provides imaging of the distribution of PCHMA in the different domains and in the matrix. It is thus observed that (i) superficial craters and large domains are formed mainly by PCHMA and (ii) the matrix is composed of PVAc in films cast from THF and it is a blend of the two polymers, homogeneous at the submicrometric scale, for chloroform. The emission intensity of Py, recorded by microfluorescence spectroscopy (MFS), yields a mapping similar to imaging detection. It is remarkable that in films cast from chloroform, the smaller domains are distributed with a 2D hexatic order disrupted by dislocations and disclinations, whereas in films cast from THF, a larger heterogeneity is found, denoting different mechanisms of solvent evaporation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009439024969
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  • 2
    Electronic Resource
    Electronic Resource
    The Syntheses and Molecular Structure of a Branched Oligosilyl Anion with a Record of Nine Silicon Atoms and of the First Branched Oligosilyl Dianion (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 1091-1095 
    Details
    ISSN: 1434-1948
    Keywords: Silicon ; Silyl anions ; Lithium ; Silanes ; Polysilyl dianions ; α,ω-Dilithiooligosilanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Me3Si)3Si(Me2Si)2(Me3Si)2SiLi (1) and LiSi(Me3Si)2(Me2Si)2Si(Me3Si)2Li (2) were synthesized by the reaction of (Me3Si)3Si(Me2Si)2Si(Me3Si)3 in THF with one or two mol-equivalents, respectively, of MeLi. Both 1 and 2 were characterized spectroscopically and by trapping reactions, and 1 also by X-ray crystallography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis of 2-Fluoro Analogues of Frontalin (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1387-1389 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Epoxidations ; Asymmetric synthesis ; Fluorine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The synthesis of enantiomerically and diastereomerically pure (-)-(1R,2R,5R)- and (-)-(1R,2S,5R)-2-fluoro frontalin (7) starting from (+)-(1S)-menthyl-(R)-toluene-4-sulfinate, methylmagnesium bromide, methyl fluoroacetate, 4-pentenyl bromide and diazomethane is described. The absolute stereochemistry was unambiguously determined by X-ray analysis of (+)-(1S,2R,5S,RS)-5, an intermediate in the synthesis of the enantiomeric (+)-(1S,2R,5S)-2-fluoro frontalin (7).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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