Polysoaps, hydrophobically modified

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]. 

Modification of poly(2-vinylpyridine) with a long-chain K-dodecyl bromide was the first published example of a polysoap in the literature [192]. (The term polysoap arises from the fact that the resulting modified polyelectrolyte displays similar properties to that of an ordinary soap [192,193].) Dependent on the aqueous solution conditions and the nature of the hydrophobe, modified polyelectrolytes can associate either intramolecularly or intermolecularly [194], and this has created interest from a technological perspective potential applications include use as associative thickeners and rheology modifiers [195]. 

A number of hydrophobically modified water-soluble polymers have been prepared via post-polymerization reaction. For example, Straus [21] has prepared polysoaps by the quarternization of poly(2-vinylpyridine) with n-dodecyl bromide (Eq. 1.3). 

Polysoaps are highly substituted hydrophobically modified polymers that exhibit abnormally compact coils because of the overwhelming effects of intramolecular association, and micellization. 

Strauss and Jackson [4] were the first to synthesize associated hydro-phobically modified poiyelectrolytes. In 1951, they partially quartemized poly(2-vinylpyridine) with n-dodecyl bromide, and showed that the polymers formed a compact conformation in aqueous solution, through hydrophobic association of the n-dodecyl groups, if the degree of quarter-nization was higher than a certain value. They called these hydrophobically modified poly(2-vinylpyridine)s polysoaps [4]. The compact conformation of these amphiphilic polycations showed an analogy with surfactant micelles in that the polymers solubilized hydrophobic small molecules in dilute aqueous solutions. Later, Strauss et al. [5,6] synthesized a series of... 

Polyelectrolytes modified via covalent bonding with long hydrocarbon chains are expected to behave as hypercoils over the entire pH range. The hydrophobic interaction between the paraffinic side chains in these systems leads to stabilization of compact structures even at high pH. Such polymers have been called polysoaps or intramolecular micelle-forming polymers. 

Hydrophobic associations in aqueous solution have been recognized in polymeric systems for some time. Their ability to enhance viscosity has led to research directed toward modifying existing water soluble polymers with alkyl substituents capable of associating in solution. These have included studies by Strauss et al. on polysoaps from polyvinylpyridine [7], Schulz [8] and McCormick... 

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