On the elasticity of polysoaps: The effects of secondary structure

Associating polymers incorporating numerous ''stickers'' are endowed with a ''secondary'' structure due to their self-assembly. Upon deformation the secondary structure equilibrates so as to lower the restoring force in accordance with the LeChatelier principle. This behaviour is analysed for the particular case of polysoaps: linear hydrophilic polymers incorporating, at intervals, amphiphilic monomers. In aqueous solution the amphiphiles form intrachain micelles. The deformation behaviour of a linear string of spherical intrachain micelles in theta conditions and high ionic strength is analysed. The results reveal two remarkable features: i) The ''spring'' constant for weak extension is stronger than the spring constant for strong extensions, when the chain is fully dissociated. ii) At intermediate extensions intrachain micelles coexist with fully dissociated chain segments leading to a regime where the strain is independent of the stress.