Invertible Micelles Based on Ion-Specific Interactions of Sr 2+ and Ba 2+ with Double Anionic Block Copolyelectrolytes

Nico Carl , Sylvain Prevost (1) , Ralf Schweins (2) , Judith Houston , Isabelle Morfin (3) , Klaus Huber

1 ESRF - European Synchrotron Radiation Facility
2 ILL - Institut Laue-Langevin
3 Laboratoire Interdisciplinaire de Physique

Polyelectrolytes show diverse ion-specific effects with a wide variety of ions. In the present work, we study the solution behavior of diblock copolymers with poly acrylate (PA) and poly styrenesulfonate (PSS) blocks in the presence of the earth alkaline cations Ca 2+ , Sr 2+ and Ba 2+. Micellization can be triggered by a variation of temperature. For Ca 2+ this micelle formation occurs at high temperatures, while for Sr 2+ and Ba 2+ it occurs at high and low temperatures with an intermediate temperature regime of single chains. Small-angle neutron scattering on a partly deuterated block 1 copolymer unambiguously revealed that at low temperatures PSS/M 2+ forms the core of the micelles, whereas at high temperatures PA/M 2+ forms the core, effectively allowing to reverse the micelle structure by changing the temperature. This inversion of the micellar morphology, induced by a dual responsive behavior can be understood by using isothermal titration calorimetry and elucidating the thermodynamics of cation binding.

Domaines: Matière Molle [cond-mat.soft]

Nico Carl, Sylvain Prevost, Ralf Schweins, Judith Houston, Isabelle Morfin, et al.. Invertible Micelles Based on Ion-Specific Interactions of Sr 2+ and Ba 2+ with Double Anionic Block Copolyelectrolytes. Macromolecules, 2019, 52 (22), pp.8759-8770. ⟨10.1021/acs.macromol.9b01924⟩. ⟨hal-02396455⟩