Polymer clusters ionic strength

The nature of the association maintains a locally effective shielding of the sulfonate anions within the aggregate and preservation of the clustered structure. This suggests that for these block polymer structures, the energetics of maintaining hydrophobic association are more favorable than monomer dispersion due to ionic repulsion. This was further demonstrasted by the extreme salt sensitivity of these polymers to solution ionic strength. Small amounts of sodium chloride resulted in polymer precipitation and of course loss of viscosification. This precludes the use of these particular polymers for chemically enhanced oil recovery and indicates the need for nonionic functionality to provide water solubility. To further pursue this approach acrylamide based polymers were studied. 

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