EXTENDING POLYSOAPS IN THE PRESENCE OF FREE AMPHIPHILES

Intramolecular self-assembly affects the elastic behavior of polymers. ''Denaturing'' agents that weaken the resulting Secondary structure s trongly modify the force laws characterizing the deformation of such p olymers. This behavior is analyzed for the particular case of polysoap s: linear hydrophilic polymers incorporating, at intervals, amphiphili c monomers. In aqueous solution the amphiphiles form intrachain micell es. The deformation behavior of a linear string of spherical intrachai n micelles in theta conditions and high ionic strength is analyzed as a function of the concentration of free amphiphiles X. At intermediate extensions intrachain micelles coexist with fully dissociated chain s egments leading to a regime where the tension f is weakly dependent on the end to end distance R. The width of the coexistence regime shrink s as X increases. At the same time, the tension at coexistence increas es. The fR diagram exhibits thus features reminiscent of a critical po int approached via control of X.