Scientists Create Gels That Switch Between Solid and Liquid With Light
Researchers have developed a gel that can be toggled between solid and liquid states using UV and visible light, with no loss of performance after repeated cycling. The breakthrough uses deep eutectic solvents—cheap, non-toxic alternatives to traditional chemicals—opening potential commercial applications in smart coatings, drug delivery, and responsive materials for manufacturing.
Originaltitel: Photocontrolled Supramolecular Gels in Deep Eutectic Solvents
Fotoresponsiva geler i djupa eutektiska lösningsmedel möjliggör mekanisk kontroll utan volatila organiska ämnen — en utveckling som öppnar nya vägar för material med dynamisk formpåverkan. Forskarna kombinerade en fotoaktiv azobenzenväxlare med amfifila molekyler i vattensfria eutektiska miljöer och uppnådde helt reversibla gel–sol-övergångar. UV-strålning utlöser isomerisering som gör gelen lös; synligt ljus återställer gelstrukturen. Systemen tål upprepad cykling med minimal prestationsförlust och påverkas inte av lösningsmedelsförångning eller långtidslagring. Ramón Rial och hans grupp vid Universidade de Santiago de Compostela utvecklade denna strategi tillsammans med institut vid ESS och ILL. För leverantörer av polymer- och gelmaterial representerar eutektogeler en möjlighet att differentiera produkter mot applikationer inom sensorik, läkemedelsdosering och adaptiva konstruktionsmaterial utan miljökritiska lösningsmedel.
An adaptable strategy for developing light-responsive eutectogels with intrinsic mechanical modulation is introduced. This was achieved through the controlled supramolecular assembly between an amphiphile and a customized azobenzene photoswitch, which displays high solubility in water-free eutectic media. Molecular and mesoscopic characterization provided a detailed understanding of the heterotypic interactions between the photoswitch and the amphiphile, as well as their respective one-dimensional assemblies. UV irradiation induces E→Z isomerization of the azobenzene trigger, enabling efficient transduction of molecular photoisomerization into assembly contraction and the loss of the solid-like character. Under visible light, the system forms robust gels supported by extended architectures that are not affected by solvent evaporation or long-term storage. Photo-induced gel–sol transitions are fully reversible and can be cycled repeatedly with marginal loss of structural and mechanical recovery. As such, this work introduces a versatile approach for the next generation of light-responsive gels based on eutectic systems.