Dresden 2003 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 20: POSTER A
CPP 20.20: Poster
Montag, 24. März 2003, 19:00–21:00, ZEU/250
Nanophase separation in amorphous side chain polymers with long alkyl rest — •H. Huth, E. Hempel, K. Schröter, and M. Beiner — Fachbereich Physik, Universität Halle, 06099 Halle, Germany
Recent results for several amorphous members of the poly(n-alkyl acrylate) series (PnAA) demonstrating the nanophase separation of incompatible main and side chain parts in these homopolymers are presented. Idea is the aggregation of alkyl rests in alkyl nanodomains with a typical size of 1-2 nm for the PnAA with C=4-10 alkyl carbons per side chain. Dynamic as well as structural indications for such demixing effects on nanometer scales are discussed. The study includes relaxation spectroscopy methods like heat capacity spectroscopy (TMDSC, 3ω method), dielectric and shear spectroscopy as well as x-ray scattering techniques (SAXS/WAXS). It is shown that the main features of the nanophase separation in PnAA are similar to those in the previously studied poly(n-alkyl methacrylates) and other side chain polymers with long alkyl rest. Especially, we observed clear evidence for the coexistence of two dynamic glass transitions also in higher PnAA. A polyethylene-like glass transition (αPE) was detected beside the conventional glass transition (α) involving the main chain. A main point of the discussion is the interrelation between the αPE process and the size of the alkyl nanodomains formed by aggregated alkyl rests in the melt. The reason for an increase of the glass temperature Tg(αPE) with increasing side chain length is discussed based on two alternative approaches: (i) increasing order within the alkyl nanodomains or (ii) confinement effects in the sense of a hindered glass transition.