Local motions of polystyrene chain in semi-concentrated polymer solutions

In the 1980s, the mechanism of local motions of polymer chain was discussed theoretically and experimentally by many researchers. Finally, the intermittent motion model was proposed with respect to the measurements of emission anisotropy decay curves of a chromophore incorporated into a polymer main chain in dilute polymer solutions. The relationship between orientational auto-correlation function type based on power law and measured decay curves was discussed in these reports. The local motion of anthryl groups end-capped polystyrene (APSA) was measured in various polystyrene/di-n-butyl phthalate mixtures by using the fluorescence depolarization method. The intermittent motion model for local motions of polymer segments is modified in order to apply to both dilute and semi-concentrated polymer solutions. The model predicts that the orientational auto-correlation function will be given by the KWW function when the segment–solvent collision is effective on the relaxation process. On the other hand, the hyperbolic function will be observed when the segment–segment collision becomes effective. It was found that measured decay curves in dilute and concentrated polymer solutions were well represented by the KWW function and the hyperbolic function, respectively. The result implies the fact that modified intermittent motion model is in good agreement with the experimental data.