Particle Scattering Factor and Segment–Segment Distance Distribution of Macromolecules in Solution

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Abstract
The angular dependence of light scattering from solutions of three samples of poly‐α‐methylstyrene in various solvents has been measured over a wide range of scattering angles. For molecules with a radius of gyration larger than about 500 Å, differences (δP) are found between the actual angular dependence (P) and the one (P id ) predicted—with Debye's equation—for ideal Gaussian coils. By subjecting the measured data to a statistical analysis, a quantitative description of δP was attained. The quantities δP contain information about the function δW(r) , which is the difference between W(r) and W id (r) ; the function W(r) is the actual distribution function for the distances between the segments in a polymer coil, whereas W id (r) is the one that follows from random‐flight statistics, underlying the ideal Gaussian coil model. The information about δW(r) was obtained by applying a Fourier inversion to the measured δP curves. Although this information is necessarily limited, the typical features of δW(r) thus found correspond with those a realistic function W(r) must possess in order to account for the impossibility of chain intersections (excluded volume effect).