We have exploited the selectivity of neutron scattering combined with isotopic substitution to study the structure and dynamics of poly(n-alkyl methacrylates). Our diffraction data strongly support the suggested nanosegregation of main-chains and side groups. Moreover, we have been able to separately follow the dynamics of both subsystems at a molecular scale. While the structural relaxation observed at the main-chain level is standard, for high-order members the correlations involving side groups within the alkyl nanodomains relax through an exotic logarithmic decay. In these polymers, a strong dynamic asymmetry also develops. We discuss possible theoretical frameworks for the anomalous relaxation observed.

We thank the ILL scientists M. Maccarini, B. Deme and P. P. Deen for experimental help, and the NoE SoftComp, Contract NMP3-CT-2004-502235, ‘Donostia International Physics Center’, the projects MAT2007-63681, IT-436-07 (GV) and the Spanish Ministerio de Educacion y Ciencia (CSD2006-53) for financial support.

Peer reviewed