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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 11: DRG-DPG SYMPOSIUM Rheology III

CPP 11.7: Vortrag

Dienstag, 26. Februar 2008, 11:45–12:00, C 264

Diffusion of Linear Macromolecules and Spherical Nanoparticles in Semidilute Polymer Solutions and Gels — •Sebastian Seiffert and Wilhelm Oppermann — Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Strasse 4, D-38678 Clausthal-Zellerfeld, Germany

The dynamics of fluorescently labeled linear macromolecules and spherical particles that are enclosed in polymer matrixes were studied by fluorescence recovery after photobleaching. The experiments were designed such that the transition from a semidilute solution to a permanent network could be covered. This was achieved by employing a matrix polymer, polyacrylamide, carrying pendent dimethylmaleimide groups. Stepwise irradiation of such samples causes dimerization of the moieties via photochemical [2+2]-addition leading to progressive crosslinking. Thus, studies on the diffusion of linear and spherical tracers are enabled especially within the interesting transition region between a physically entangled system and a covalently crosslinked matrix. Comparability of the results is ensured since the same sample is analyzed merely at different degrees of crosslinking, respectively. The parameters varied were the concentration of matrix polymer and the molar mass of the enclosed linear chains as well as the size of the spheres. The aim of this study is to point out differences between the dynamics of linear tracers in contrast to spherical particles and to work out the behavior of the system when a semidilute polymer solution is chemically crosslinked. A central problem in this context is the adaptability of the reptation model in fairly dilute systems.