Competition between Conformational and Chemical Equilibrium in Suspensions of Polyelectrolyte-Coated Particles

The results of the comparative analysis of the conformational and chemical Equilibrium in suspensions of polyelectrolyte-coated particles are presented. The free energy difference between stretched, more ionized, chains and random, more neutral ones can be very slight, resulting in conformational disturbances in the chains in the corona of a micelle, leading to bimodal monomer distributions. The assumption of uniform charge density along the chains of the corona precludes any cooperative ionization phenomena, specifically, ionization in one region of the chain decreasing the likelihood the nearby portions of the chain will also become ionized. The interplay between the free energy of ionization, the free energy changes associated with conformational changes, screening, and Coulombic interactions within the brush can lead to new phases within the corona. Allowing the monomers to establish their own ionization equilibrium has significant effects.