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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 34: POSTERS Polymerphysics

CPP 34.22: Poster

Donnerstag, 28. Februar 2008, 17:00–19:30, Poster A

Side chain dynamics and crystallization in nanophase-separated regio-random poly(3-alkyl thiophenes) — •Shireesh Pankaj, Elke Hempel, and Mario Beiner — Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle/Saale, Germany

A series of regio-random poly(3-alkyl thiophenes-2, 5-diyl) has been investigated by differential scanning calorimetry, x-ray scattering and dynamic mechanical analysis. Samples with varying side chain lengths from C=4 to C=12 alkyl carbons were studied to understand details of the interplay between structure and cooperative dynamics in these nanophase-separated side chain polymers. Two glass transitions are observed for the amorphous members (C=4−8) like in previously studied atactic poly(n−alkyl methacrylates). In both cases, the aggregation of alkyl groups to small alkyl nanodomains with a typical dimension of about 1 nm is indicated by a prepeak in x-ray scattering data. Crystallization of alkyl groups within the alkyl nanodomains is seen for the higher thiophenes, i.e., for the decyl (C=10) and dodecyl (C=12) members. A special feature which is observed for the dodecyl member is that different melting peaks are seen depicting polymorphism of the crystallizable side chains. This is not observed in poly(n−alkyl methacrylates) and poly(n−alkyl acrylates) with similar side chain lengths. Isothermal crystallization results for these samples are presented and discussed in the light of recently developed theories of polymer crystallization.