Dynamics of Semiflexible Polymers in Concentrated Solution : A Study by Optically-Labeled Dynamic Light Scattering

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The present research project was concerned with the dynamics of semiflexible polymer in concentrated solution. The main results are summarized in the following :(1) Using the fuzzy cylinder model, the dynamical structure factors of binary and ternary semiflexible polymer solutions were formulated on the basis of Doi et al.'s dynamical mean-field theory, which was originally applied to rodlike polymer solutions. The formulated structure factors were used to analyze dynamic light scattering data mentioned below.(2) Dynamic light scattering measurements were made for dichloromethane (DCM) solutions of a semiflexible polymer, poly (n-hexyl isocyanate) (PHIC), to obtain the mutual diffusion coefficient as a function of the polymer concentration and molecular weight. Previously, the same system was studied by viscometry.(3) A semiflexible polymer, poly (3-benzyloxy-carbonyl) -n-propyl isocyanate) (PBPIC), which was used for the optically-labeled dynamic light scattering experiment mentioned … More below, was molecularly characterized in terms of the wormlike chain model. The wormlike chain parameters determined were used to compare optically-labeled dynamic light scattering data with the fuzzy cylinder model theory mentioned in (6).(4) Dynamic light scattering measurements were made for ternary solutions consisting of PBPIC,PHIC,and toluene, where toluene is an isorefractive solvent for PHIC so that light is scattered only by PBPIC.These optically-labeled dynamic light scattering measurements gave us the self-diffusion coefficient of PBPIC in PHIC solutions.(5) The fuzzy cylinder model theory was modified by including the effect of the intermolecular hydrodynamic interaction in polymer solutions with finite concentrations.(6) The modified fuzzy cylinder model theory was favorably compared with the experimental results of the mutual diffusion coefficient of DCM solutions of PHIC and of the self-diffusion coefficient of PBPIC in PHIC solutions. The theory consistently explained the translational diffusion and zero-shear viscosity behavior of DCM solutions of PHIC. Less