Amorphous polymer dynamics and free volume element size distributions from ultrafast IR spectroscopy.

ABSTRACT: A method for measuring the size and size probability distribution of free volume regions in polymeric materials using ultrafast infrared (IR) polarization-selective pump-probe experiments is presented. Measurements of the ultrafast dynamics of a vibrational probe (the CN stretch of phenyl selenocyanate) in poly(methyl methacrylate) show that the probe dynamics are highly confined. The degree of confinement was found to be both time-dependent and dependent on the vibrational frequency of the probe molecule. The experiments demonstrate that different vibrational frequencies correspond to distinct subensembles of probe molecules that have different dynamic properties determined by their local structural environments. By combining the degree of dynamical confinement with the molecular size of

SUBMITTER: Hoffman DJ 

PROVIDER: S-EPMC7322021 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature