Relaxation of Copolymeric Dendrimers Built from Alternating Monomers

Authors

  • Cristian Satmarel,

    1. Theoretische Polymerphysik, Universität Freiburg, Hermann-Herder Str. 3, D-79104 Freiburg, Germany
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  • Andrey A. Gurtovenko,

    1. Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi Prospect 31, V.O., St. Petersburg, 199004, Russia
    2. Laboratory of Physics and Helsinki Institute of Physics, Helsinki University of Technology, P.O. Box 1100, FIN-02015 HUT, Finland
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  • Alexander Blumen

    Corresponding author
    1. Theoretische Polymerphysik, Universität Freiburg, Hermann-Herder Str. 3, D-79104 Freiburg, Germany
    • Theoretische Polymerphysik, Universität Freiburg, Hermann-Herder Str. 3, D-79104 Freiburg, Germany. Fax: +49 761 203 5906
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Abstract

Summary: In this study we extend our previous work concerning the Rouse dynamics of linear alternating copolymers (Macromolecules2003, 36, 486) to tree-like structures and focus on copolymeric dendrimers built from monomers of two kinds A and B; as before, we let the monomers differ in their interaction with the solvent. In the framework of generalized Gaussian structures (GGS), we consider alternating arrangements of monomers over the dendritic structures. We develop a semi-analytical method to determine for such structures (of arbitrary functionality, f, and number of generations, g), the eigenfrequencies (relaxation times). The method allows us to compute readily the storage, [G′(ω)] and the loss, [G″(ω)] moduli. These quantities show a multitude of features which mainly depend on the difference in the mobilities, or, equivalently, in the friction coefficients ζA and ζB of the A- and B-beads. These features range from the presence of large plateau-type regions in [G′(ω)] to the appearance of double-peaks in [G″(ω)]. In contrast to linear alternating copolymers, the behavior of the dynamic moduli of copolymeric systems with dendritic topology can shed light into their composition, i.e. into the relative numbers of A- and B-beads. We discuss these aspects in view of their experimental relevance.

original image

A system under study: a dendrimer of third generation (g = 3) with functionality f = 3, composed of alternating beads.

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