Tuning at will the properties of gel-forming systems is of key relevance for many biotechnological, agricultural, and biomedical applications. For polyelectrolyte-based gels, ion-specific effects can be an attractive way for this purpose. We investigate the ion-specific effect on a physical hydrogel formed of cationic polyelectrolytes (ionenes), contrasting gels with chloride and fluoride ions. The combination of complementary small-angle X-ray and neutron scattering (SAXS and SANS) techniques reveals a strong contribution of ion−ion correlations in the structure of the gel network. Contrary to chloride gels, which present a single correlation length characterizing the distance between the cross-linking nodes, fluoride gels present an additional network of nodes. This is accompanied by a very rapid increase of the elastic modulus of fluoride gels, once the critical gelation concentration (CGC) is reached.
Claire Hotton, Juliette-Sirieix Plenet and Natalie Malikova of PHENIX in collaboration with Guylaine Ducouret (SIMM), Thomas Bizien (Soleil), Lionel Porcar (ILL).
https://pubs.acs.org/doi/10.1021/acs.macromol.2c01565
