Impermeable coil limit

It should be pointed out that in the Zimm, or impermeable coil, limit the specific value of R ff is uninfluential since the friction coefficient C( ) = C/v( ) is independent of R ff, see Eqs. (3.1.7 ) and (3.1.9), v( ) > 1. This is not true in the partial-draining case, in which v(q) is of order unity although larger than the Rouse free-draining limit v(q) = 1, and its full expression must be considered. 

The intrinsic viscosity ( /] is obtained by extrapolation of reduced viscosity of the dilute polymer solution (q-qs)lcqs> to zero polymer concentration, c—>0 (here rj is the viscosity of the polymer solution and the viscosity of pure solvent). In the nondraining limit of large N, the coils behave in a shear flow as impermeable for the solvent particles of effertive radius J ,. In dilute-solution limit, the Einstein equation i/ = i/s[l+ (5/2) ] applies, where is the volume fraction of particles in the solution. Hence, the intrinsic viscosity [i/] measures the (inverse) average intramolecular concenttation of the monomer units assuming that they are confined within a sphere of radius J ,. 

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