Angular dependence of the light scattering of polymer solutions at moderate concentrations especially near the consolute point

Abstract

The light scattering equation ℋ︁c₂(1 + cos² θ)/R_θ = dΠ/RTdc₂ + (16 π² 〈r²〉/3λ²)M₂⁻¹ sin²θ/2 for moderately concentrated polymer solutions derived previously from a gradient dependent free energy will here be rederived with the help of the so‐called direct correlation function, C(s), first introduced by Ornstein and Zernike.The equation will be used to calculate 〈r²〉/M₂ for polystyrene in cyclohexane near the consolute (or critical) point from light scattering measurements of Debye, Coll, and Woermann in combination with those of Scholte We found [〈r²〉/M²]^1/2 = 3.5 (± 0.1) nm mol^1/2 g^−1/2 for M₂ ranging from 8 × 10⁴→ 10⁶ g mol⁻¹.