Polyelectrolytes: From Seminal Works to the Influence of the Charge Sequence

Abstract

We propose a selected tour of the physics of polyelectrolytes (PE) following the line initiated by de Gennes and coworkers in their seminal 1976 paper. The early works which used uniform charge distributions along the PE backbone achieved tremendous progress and set most milestones in the field. Recently, the focus has shifted to the role of the charge sequence. Revisited topics include PE complexation and polyampholytes (PA). We develop the example of a random PE in poor solvent forming pearl-necklace structures. It is shown that the pearls typically adopt very asymmetric mass and charge distributions. Individual sequences do not necessarily reflect the ensemble statistics and a rich variety of behaviors emerges (specially for PA). Pearl necklaces are dynamic structures and switch between various types of pearl-necklace structures, as described for both PE and PA.

Role of Charge Sequence in Polyampholyte Aggregation

“…The counterion population in this layer (or in the sublayer of width σ) increases linearly with interfacial area, resembling an a priori lump of dense phase surrounded by an interfacial layer whose structure is independent of its size. (3) Following our own work 47,48 and works by others, 21,43 we expect the PA with a given sequence to aggregate more for increasing sequence blockiness, essentially blockiness of the minority charge matters. Simulations validate the anticipated correlation: higher blockiness amplifies polarization and surface tension, 40−42 hence promoting aggregation.…”