Selective dynamics in polymeric materials: Insights from quasi-elastic neutron scattering spectroscopy

Polymeric materials exhibit a rich hierarchy of dynamics from fast sub-molecular motions to collective segmental relaxations and slow chain diffusion. Such dynamical hierarchy dictates that the performance of polymeric materials is tightly linked to fast molecular dynamics, necessitating a thorough understanding of the dynamic behavior of polymers on the nanoscale. Recent advances in the synthesis of polymer composites with nanoscale fillers further amplify the need to probe polymer dynamics over spatial and temporal nanoscales to achieve reliable engineering of materials with well-defined properties. This tutorial focuses on the efficacy of neutron spectroscopy techniques, combined with judicious hydrogen/deuterium labeling, in selectively probing local and collective dynamics that underlie macroscopic properties in polymeric materials with varying degrees of complexity.