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 intermi ttent motion model was proposed with respect to the measurements of emissio n 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 measur ed in various polystyrene/di-n-butyl phthalate mixtures by using the fluore scence depolarization method. The intermittent motion model for local motio ns of polymer segments is modified in order to apply to both dilute and sem i-concentrated polymer solutions. The model predicts that the orientational auto-correlation function will be given by the KWW function when the segme nt-solvent collision is effective on the relaxation process. On the other h and, the hyperbolic function will be observed when the segment-segment coll ision becomes effective. It was found that measured decay curves in dilute and concentrated polymer solutions were well represented by the KWW functio n and the hyperbolic function, respectively. The result implies the fact th at modified intermittent motion model is in good agreement with the experim ental data. (C) 2001 Elsevier Science Ltd. All rights reserved.