Dilution-induced gel-sol-gel-sol transitions by competitive supramolecular pathways in water.

Su, Lu; Mosquera, Jesús; Mabesoone, Mathijs F J; Schoenmakers, Sandra M C; Muller, Cyprien; Vleugels, Marle E J; Dhiman, Shikha; Wijker, Stefan et al. · Science · 2022

basic_science · Level V

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Abstract

Fascinating properties are displayed by synthetic multicomponent supramolecular systems that comprise a manifold of competitive interactions, thereby mimicking natural processes. We present the integration of two reentrant phase transitions based on an unexpected dilution-induced assembly process using supramolecular polymers and surfactants. The co-assembly of the water-soluble benzene-1,3,5-tricarboxamide (BTA-EG<sub>4</sub>) and a surfactant at a specific ratio yielded small-sized aggregates. These interactions were modeled using the competition between self-sorting and co-assembly of both components. The small-sized aggregates were transformed into supramolecular polymer networks by a twofold dilution in water without changing their ratio. Kinetic experiments show the in situ growth of micrometer-long fibers in the dilution process. We were able to create systems that undergo fully reversible hydrogel-solution-hydrogel-solution transitions upon dilution by introducing another orthogonal interaction.