Anionic polyelectrolyte chains act extremely sensitive towards the addition of specifically interacting cations (SIC). This sensitive response can be further modulated by variations of pH, temperature and ionic strength with additional inert salts. Typical SICs, which interact specifically with the anionic carboxylate residues of polyacrylates or with the anionic sulfonate residues of poly(styrene sulfonate) are alkaline earth cations. This is signaled by a drastic change of the polyelectrolyte coil dimensions and eventually in a precipitation of the respective polyelectrolyte salt, once the SIC content is large enough. Such a sensitivity to SICs make SIC-polyelectrolyte combinations ideal candidates for responsive materials or modulators in mineralization processes. Our main focus lies on a comparative study of the impact of SICs on polyacrylate and poly(styrene sulfonate). The subtle interplay of temperature and ionic strength with appropriate amounts of SIC enables us to control and analyse the extent of shrinking of the polyelectrolyte coil dimensions close to the precipitation threshold. Block-copolyelectrolytes of polyacrylate and poly(styrene sulfonate) combine diverse response patterns and thus give access to enterily new self organisation processes like the formation of micelles and their inversion by simple temperature changes in the presence of Sr2+ or Ba2.  

Hansch, M. et al.
Liquid-liquid phase separation in dilute solutions of poly(styrene sulfonate) with multivalent cations: Phase diagrams, chain morphology, and impact of temperature
J. Chem. Phys. (2018) 148 (1), 014901 DOI: 10.1063/1.5006618

Hansch, M. et al.
Reaction enthalpy from the binding of multivalent cations to anionic polyelectrolytes in dilute solutions
J. Chem. Phys. (2018) 148 (11), 114906 DOI: 10.1063/1.5019877

N. Carl, et al.
Ion-selective binding as a new trigger for micellization of block copolyelectrolytes with two anionic blocks
Soft Matter (2019) 15 (41), 8266 - 8271 DOI: 10.1039/C9SM01138B

Carl, N. et al.
Invertible Micelles Based on Ion-Specific Interactions of Sr2+ and Ba2+ with Double Anionic Block Copolyelectrolytes
Macromolecules (2019) 52 (22), 8759−8770 DOI: 10.1021/acs.macromol.9b01924