Polymer Chain Dynamics I. Estimation of Orientational Auto-Correlation Function for Polymer Chains

Abstract

Fluorescence anisotropy decay curves of polystyrene labeled with an anthryl group in the middle of a main chain (PSAPS) were measured by the time-resolved fluorescence depolarization method. We studied an adequate orientational auto-correlation functions (OACF) to explain fluorescence anisotropy decay curves of PSAPS. The goodness of fitting to measured anisotropy decays is evaluated by an original fitting program based on Wahl’s argolithm. However it was difficult to distinguish the most adequate OACF from many reported ones only by the comparison of the values of the residual sum of squares. Consideration of the meaning of variable parameters contained in many OACF reported has been done from the viewpoint that OACF should refrect the distribution of relaxation rate. Furthermore, a novel method for estimation of OACF called χ2-map method was used. As a result the hyperbolic function is one of the most adequate OACF in order to express effectively the fluorescence anisotropy decay curves of PSAPS chains.