Abstract
A theory of elastic (Rayleigh–Debye) light scattering by an isotropic system composed of anisotropic units is developed. Each unit is regarded optically as a point scatterer with three different principal polarizabilities. No assumption is introduced about the radial and orientational distributions for any pair of units. The only assumption is the random orientation of the system as a whole with respect to the light-scattering framework (“isotropic” system). Theory is formally adapted to infinitely dilute solutions of polymers of completely general structure. Detailed calculations are carried out for the Porod–Kratky wormlike chain. A method is suggested for determining the parameters of the Porod–Kratky chain through comparison of the theory with experimental data on polymer chains of moderate length. Chain-length dependences of various terms in expressions for reduced intensities are inferred for general chains from those for the Porod–Kratky chain. The correspondence of the Porod–Kratky chain with general chains is thereby discussed. A detailed comparison is also made of our results for the Porod–Kratky chain and general chains with those for the random chain reported by Utiyama and Kurata.
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Nagai, K. Theory of Light Scattering by an Isotropic System Composed of Anisotropic Units with Application to the Porod–Kratky Chain. Polym J 3, 67–83 (1972). https://doi.org/10.1295/polymj.3.67
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DOI: https://doi.org/10.1295/polymj.3.67