Figure 7. Rg (P) ofPDMS (Mw=22500) in SC CO2 Figure 8. Ç(t) ofPDMS (Mw=22500) in SC CO2.

at T-70OC.The inset shows Rg (T) at p co2=0.95 Pco2=0.95 g/cm3 The inset shows ^(x) forthesame g/cm3.

polymer in BrBz-d.

Despite numerous efforts, the dynamic properties of semidilute polymer solutions in organic solvents at T < © are poorly understood. To our knowledge, only one DLS experiment has been performed so far in the poor solvent domain of supercritical polymer solutions [4]. The most important issue which is yet to be resolved is whether the viscosity of the solvent or that of the solution should be used to calculate the dynamic correlation length from the Stokes-Einstein Eq.12 [31].

In terms of a traditional description of critical phenomena, the temperature variation of the dynamic and static correlation lengths may be represented as [32]:

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