Regensburg 2002 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 4: Poster: Dynamik in polymeren Systemen
CPP 4.5: Poster
Montag, 11. März 2002, 13:30–15:00, B
Structural and dynamic nanoheterogeneities in side chain polymers — •S. Reichl, H. Huth, O. Kabisch, E. Hempel, and M. Beiner — Fachbereich Physik, Universität Halle, D-06099 Halle/Saale
Dielectric, shear, and heat capacity spectroscopy data indicate the co-existence of two dynamic glass transitions in higher poly n-alkyl methacrylates (PnAMAs). X-ray scattering (SAXS) data show a pre-peak that corresponds to repeating distances in the range dII=1-3nm. The dII value increases systematically with side chain length. Both findings are consistent with a nanophase separation of incompatible main and side chain parts. The interrelation between structure and dynamics in nanophase-separated polymers is discussed. The α PE process at lower temperature is a No-dqpolyethylene-likeNo-dq glass transition within nanodomains formed by aggregated alkyl rests. The size of dynamic heterogeneities relevant for the α PE process, ξ α PE, is calculated from calorimetric data for poly n-decyl methacrylate using different thermodynamic approaches. The ξ α PE values obtained from the fluctuation approach by Donth are consistent with the size of the alkyl domains while other approaches give unexpected large ξ α PE values. In order to come to a final morphology picture for nanophase-separated PnAMAs the influence of side chain length and polymerization degree on SAXS data is studied in detail. It is shown that the ultimate nanostructure is already reached for chains with ≈25 monomeric units and that changes depending on side chain length occur near the decyl member. The scattering behavior at low q < 1nm−1 values and the morphology of crystalline PnAMAs (C=16,18 alkyl carbons) are discussed. Results for poly n-alkyl acrylates are shown for comparison.