Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 27: Poster: (Hydrogels) and Elastomers
CPP 27.13: Poster
Mittwoch, 28. März 2012, 11:00–13:00, Poster A
On the structure of Star Polymer Networks — •Michael Lang1, Konrad Schwenke1,2, and Jens-Uwe Sommer1 — 1Leibniz Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany — 2Institut f. Baustoffe (IfB), ETH Zürich, Schafmattstrasse 6, 8093 Zürich, Switzerland
Using the bond fluctuation model we study polymer networks obtained by end-linking of symmetric 4-arm star polymers. We consider two types of systems. Solutions of one type (A) of star polymers and solutions of two types (A,B) of star polymers where A-type polymers can only crosslink with B-type polymers. We find [1] that network defects in A networks are dominated by short dangling loops close to overlap concentration c*. AB networks develop a more perfect network structure, since loop sizes involving an odd number of stars are impossible, and thus, the most frequent dangling loop with largest impact on the phantom modulus is absent. The analysis of the pair-correlation and scattering function reveals an amorphous packing of A and B type stars in contrast to the previously suggested crystalline like order of A and B components at c*. Furthermore, we derive the vector order parameters associated with the most frequent network structures based on the phantom model. In particular for AB networks we can show that there is a dominating cyclic defect with a clearly separated order parameter that could be used to analyze cyclic network defects.
[1] K. Schwenke, M. Lang, J.-U. Sommer, Macromolecules, in press.