Studies on Diffusion of Rhodamine B Labeled Polystyrene in Dilute and Semidilute Solutions by Fluorescence Correlation Spectroscopy

1. Introduction Our understanding of polymer dynamics has greatly improved due to the reptation model and the scaling ideas. [1] According to scaling and reptation theory, the diffusion coefficient in semidilute or concentrated regimes is related to the molar mass and polymer concentration by D ~ M-2 c-1.75 and D ~ M-2 c-3 for good-solvent and θ-solvent conditions, respectively. In a limited range of polymer concentration, these relationships are supported by experimental data. [2-5] Fluorescence correlation spectroscopy (FCS) can be used to study the dynamics in a wide concentration range. However, the application of FCS in polymer science has almost entirely been limited to the area of biomacromolecules and aqueous media [6,7] and the application of FCS in organic media is rarely reported. [8] In this work, the diffusion of Rhodamine B labeled polystyrene (PS) chains in dilute and semidilute toluene solutions was studied by FCS.