Chemists find a contrary effect: how diluting with water makes a solution firm

Amazing stuff!

"... What is extraordinary, however, is that if the solution is diluted even further, a gel is formed again. Other supramolecular structures now form and it becomes a hydrogel again. And if it is then diluted even further, it becomes a liquid again. The paper carefully examined what the correct proportions of the active substances should be and at which concentrations the phase transitions take place. These transitions are also fully reversible. If concentrations are increased, the transitions from liquid to gel to liquid to gel occur at the same points. ...
but it is certain that it will have a major impact on chemistry and biology. ..."

From the 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-EG4) 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."

Chemists find a contrary effect: how diluting with water makes a solution firm Today, in Science Magazine, TU/e researchers have published their research on new phase transitions of solutions and gels in water, which instinctively go against the basic principles of chemistry – and which they discovered by accident. In chemistry, everyone learns that you can go from a hydrogel to a liquid by diluting the hydrogel with water. For the reverse transition, you increase the concentration. However, TU/e researchers led by Bert Meijer accidentally discovered that their liquid solution turned into a hydrogel when diluted. This phenomenon hadn’t been researched or described before and will have consequences in many areas in chemistry and biology. The finding, which appears today in Science Magazine, was made and researched thanks to exceptional teamwork.

Dilution-induced gel-sol-gel-sol transitions by competitive supramolecular pathways in water (no public access)