Simple Coacervation of Guanidinium-Containing Polymers Induced by Monovalent Salt

Liquid–liquid phase separation (LLPS) of macromolecules, called coacervation, is induced by non-covalent intermolecular associations in aqueous solutions, which is frequently observed in biological processes including cellular compartmentation, signaling, and regulation. Recently, associative interactions between π-conjugated residues have emerged to induce LLPS, along with electrostatic interaction. An arginine residue having a positively charged guanidinium group plays a pivotal role in protein phase behavior because the orientational amphiphilicity of guanidinium groups allows face-to-face π–π stacking despite Coulombic repulsion. In this study, we investigate the simple coacervates of guanidinium-functionalized polyelectrolytes ( i.e., poly-arginine) in aqueous media as a function of salt concentration, salt type, and temperature to understand the exclusive role of π-conjugated moiet…