Antipolyelectrolyte

The surface activity and solubihzation capacity of amphoteric polysoaps were studied [172,177,178]. The surface activity of zwitterionic polysoaps is diminished by added salt due to their antipolyelectrolyte character. The sequence to solubihze hydrophobic dyes is often mid-tail > head > tail-end geometry. An extended study on the solubilization abihty of hydrophobically modified polybetaines can be found in [232]. The surface activity of the cyclocopolymers containing the pH-responsive hydrophobic monomer WAf-diallyl-N-methylamine and the salt-sensitive sulfobetaine monomer 3-(WAf-diallyl-N-methylammonio) propanesulfonate was utilized to solubilize p-cresol within microdomains [233]. Other studies corroborate the general picture [182,183]. 

The addition of simple salts leads to swelling of neutral polyampholytes if they are soluble and dissolve the precipitate if they are insoluble ( antipolyelectrolyte effect). 

Previously, wel had shown that hydrophobically associating polymers can be isoviscous in salt solutions of increasing brine level. We [13,14] and others [15,16] has also shown that aqueous poly zwitterions are antipolyelectrolytes i.e. their solubility and viscosity increases with increasing salt content. 

Our group has examined copolymers and terpolymers from the hydrolytically resistant comonomers 1 Ij and 2 in which the cation and anion are evenly spaced from the macromolecular Imckbone (Scheme 2) 26-30). At equimolar incorporation of the monomers into the copolymer, a minimum in the apparent viscosity in water and a maximum in apparent viscosity in 0.514 MNaCl was observed - consistent with the so-called antipolyelectrolyte effect Simile effects are observed when acrylamide (3) is incorporated as a termonomer. A three-fold enhancement in viscosity was observed at a molar ratio of 11 13 76 for monomers (la 2 2) in 0.5 MNaCl as compared to deionized water (29). 

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