ON THE ELASTICITY OF POLYSOAPS - THE EFFECTS OF SECONDARY STRUCTURE

Associating polymers incorporating numerous ''stickers'' are endowed w ith a ''secondary'' structure due to their self-assembly. Upon deforma tion 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 pol ymers incorporating, at intervals, amphiphilic monomers. In aqueous so lution the amphiphiles form intrachain micelles. The deformation behav iour of a linear string of spherical intrachain micelles in theta cond itions and high ionic strength is analysed. The results reveal two rem arkable features: i) The ''spring'' constant for weak extension is str onger than the spring constant for strong extensions, when the chain i s fully dissociated. ii) At intermediate extensions intrachain micelle s coexist with fully dissociated chain segments leading to a regime wh ere the strain is independent of the stress.