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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 2777-2783 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis and characterization of Cell-SAc 3, a cellulose isopentyl (IP) ether with additional pendant S-acetyl (SAc) moieties (degree of substitution DSIP = 2.5, DSSAc = 0.4) are reported. Cell-SAc forms stable monolayers at the air-water interface once spread from dilute chloroform solution. The pressure-area isotherm of Cell-SAc is nearly identical to the parent Cell-IP 1, both exhibiting an expanded liquid phase at surface areas of 70 and 67 Å, respectively. The similarity of the two isotherms shows that the presence of the S-acetyl substituent does not result in an increase in the molecular area, at which the liquid-crystal analogous phase occurs. This observation suggests that the side-chains with the pendant S-acetyl group are oriented away from the water surface. Monolayers of Cell-SAc can be efficiently transferred onto silicon and hydrophobized glass or quartz substrates by a downstroke and upstroke technique. Resulting multilayers were characterized using X-ray reflection, FTIR, and UV-vis spectroscopy. The presence of S-acetyl moieties was found to increase the monolayer thickness relative to the parent Cell-IP. The cleavage of the S-acetyl group within the LB film is reported.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new photocrosslinkable polymer designed for application in second harmonic generation has been prepared and tested for frequency doubling of IR lasers. The polymer is based on a colorless polyurethane with pendant tolane nonlinear optical chromophores that carry a polymerizable styrene moiety at their extremities. Photocrosslinking is achieved by irradiation of films containing a small amount of a bleachable radical photoinitiator. The effect of photoinduced radical crosslinking on the mobility of the chromophores has been studied by recording the intensity of the frequency doubled light, generated by a poled sample, with increasing temperature. As expected, photocrosslinking leads to NLO materials with highly stable chromophore orientation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-193X
    Keywords: Phenyleneethynylene ; Oligomers ; Alkynes ; Protective groups ; Repetitive synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Monodisperse oligo(para-phenyleneethynylene)s (oligoPPEs) were synthesized by a divergent-convergent synthesis starting from 1,4-dihexyl-2-(3-hydroxyprop-1-ynyl)-5-[2-(triisopropylsilyl)ethynyl]benzene and using the Pd/Cu-catalyzed alkyne-aryl coupling. The groups hydroxymethyl (HOM) and triisopropylsilyl (TIPS) function as orthogonal protective groups for the acetylene moieties. The polar HOM group shows a strong impact on the chromatographic behaviour of the products and makes the isolation of pure compounds very easy. The synthesis was pursued up to the nonamer. The oligoPPEs were fully characterised, including absorption and emission spectral data.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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