Nanoconfinement through self-assembly in homopolymers with long alkyl side-groups: observation of anomalous relaxation

Abstract

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 can find similarities with other soft materials where nanoconfinement is a key ingredient, like dynamically asymmetric miscible polymer blends. These analogies suggest a general scenario for the anomalous relaxation situation observed which could be explained in terms of a high-order Mode Coupling transition.