Solvent effects intermediate regime

S(q, co). As stated earlier, such a slow tail in F(q, t) can significantly increase the friction. In calculating the friction, the effect of the inhomogeneity on the static and dynamic correlations is to be considered only for intermediate and long wavenumbers. The small wavevector limit probes the collective dynamics of the solvent, and hence it is the average friction which contributes in this region. It is fair to assume that qa 1 separates small from intermediate wavenumber regime. 

Fig. 19 (a) Intermediate scattering function C(, r) of hard sphere PMMA (7 h = 205 nm) suspension (in cz5-decalin) at qR = 2.68, from the dilute to the glassy regimes (volume fraction (+) 0.494, open circle 0.528, open triangle 0.535, open square 0.558, (x) 0.567, diamond 0.574, solid triangle 0.581, solid circle 0.587). Solid lines represent MCT fits. Taken from [237]. (b) Respective response of a colloidal polybutadiene star suspension (in good solvent cyclohexane, at 20°C) at different values of the effective hydrodynamic volume fraction c/c open circle 0.06, open square 0.72, asterisk 1.02, open triangle 1.48. Taken from [248]... 

Furthermore, by examining how an effective exponent varies with molecular mass and temperature, it is possible to determine whether one has to do with the intermediate or with the asymptotic regime of the polymer state in good solvent. 

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