Validity of Single Fluorescent Molecule to Report Local Dynamics of a Polymer Matrix: The Effect of Molecular Architecture

The influence of van der Waals volume as well as molecular configuration of the probe on its rotation is investigated by defocused single molecule fluorescence microscopy. The results show that the probe with a larger van der Waals volume has lower integrated power spectra density and the fraction of rotational molecules at each temperature. However, the asymmetric configuration of probe can make the integrated power spectra density and the fraction of rotational molecules larger. Therefore, the van der Waals volume of probe is the most dominating factor to determine the length scales and frequency of reported local dynamics while the asymmetric configuration of probe can bring about additional effect.