https://doi.org/10.1351/goldbook.12263
Theory, based on the pearl-necklace model, that describes the translational diffusive and viscous flows of an isolated linear macromolecule in solution in the theta state and accounts for the gradual change from free-draining behaviour at lower molecular weights to impermeable behaviour at higher molecular weights.
Note: The Kirkwood–Riseman theory is usually applied in the impermeable limit when it essentially relates the equivalent hydrodynamic radius to the root-mean-square unperturbed radius of gyration, \(\lt\!s_{\circ}^{2}\!\gt\), with \[r_{D} = 0.675 \lt\!s_{\circ}^{2}\!\gt^{1/2}\] and \[r_{\eta} = 0.256 \lt\!s_{\circ}^{2}\!\gt^{1/2}\] where \(r_{D}\) and \(r_{\eta}\) are the equivalent hydrodynamic radii in translational diffusive flow and viscous flow.