Abstract
We demonstrated recently that polyelectrolytes with cationic moieties along the chain and a single anionic head are able to form physical hydrogels due to the reversible nature of the head-to-body ionic bond. Here we generate a variety of such polyelectrolytes with various cationic moieties and counterion combinations starting from a common polymeric platform. We show that the rheological properties (shear modulus, critical strain) of the final hydrogels can be modulated over three orders of magnitude depending on the cation/anion pair. Our data fit remarkably well within a scaling model involving a supramolecular head-to-tail single file between cross-links, akin to the behaviour of pine-processionary caterpillar. This model allows the quantitative measure of the amount of counterion condensation from standard rheology procedure.
References:  Ion pairing controls rheological properties of “processionary” polyelectrolyte hydrogels - H. Srour, M. Duvall Ayagou, T. Thanh-Tam Nguyen, N. Taberlet, S. Manneville, C. Andraud, C. Monnereau et M. Leocmach - Soft Matter (2016), 10.1039/C6SM02022D