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  • 1
    ISSN: 1435-1536
    Keywords: Polymerblends ; fluorescence decay ; polymer colloids ; energy migration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fluorescence polarization measurements have been carried out in hydrocarbon solvents on non-aqueous colloidal polymer dispersions labelled with anthracene [A] groups. The polymer particles are composed (dry volume) of 9% polyisobutylene and 91% poly(methyl methacrylate) [PMMA]. The A groups were introduced during particle synthesis using 9-anthrylmethyl methacrylate as a comonomer with MMA. The extent of polarization decreases with increasing A content of the PMMA phase and increasing temperature increases the steady state fluorescence polarization. These results can be explained in terms of immobile A groups which are sufficiently close that some energy transfer [A*+A→A+A*] contributes to fluorescence depolarization.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 1635-1642 
    ISSN: 0887-6266
    Keywords: cyclization ; fluorescence ; polystyrene ; hydrogen bonding ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cyclization of a polystyrene chain (Mn = 10,600; Mw/Mn = 1.09) both ends labeled with 4-(1-pyrenyl)butanoamide groups was studied in cyclohexane between 25 and 95°C. The amide groups (peptide bonds) at both ends can form an intrachain hydrogen bond between the amide hydrogen at one chain end and the carbonyl oxygen at the other. The presence of two sets of conformers, random coils, and chains cyclized through hydrogen bonding, complicates the data analysis. The pyrene excimer kinetics of this polymer is well described by a model composed of two monomers (hydrogen bonded and nonbonded chains) and one excimer, in equilibrium. The cyclization rate constant for hydrogen-bonded chains is larger than the one for nonhydrogen-bonded chains. The pyrene excimer binding energy (ca. 1.6 kcal/mol) is lower than the published value for nonhydrogen-bonded chains (∼ 9 kcal/mol), suggesting that intrachain hydrogen bonding hinders the stabilization of the excimer. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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