A new class of promising materials has been developed by American researchers. Named "glass gels," these materials boast impressive hardness and flexibility, paving the way for numerous potential applications.
Glass gels are composed of rigid polymers, similar to those used in manufacturing water bottles or airplane windows, combined with ionic liquids. This unique combination allows the material to retain more than 50% of its liquid content while remaining hard and difficult to break. These gels can stretch up to five times their original length without breaking, unlike conventional glassy polymers, which are typically brittle.
Michael Dickey, professor of chemical and biomolecular engineering at North Carolina State University and corresponding author of the study, explains: "We have created materials that are as hard as glassy polymers but can stretch significantly under sufficient force. Additionally, these materials can recover their original shape when heat is applied." These properties are achieved through strong electrostatic interactions between the solvent ions and the polymer chains, which prevent the chains from moving while increasing the free space between them.
Glass gels also stand out for their excellent electrical conductivity, superior to that of conventional plastics. Meixiang Wang, co-lead author of the study and postdoctoral researcher at North Carolina State University, points out: "Their high liquid content makes them more effective at conducting electricity than plastics with similar physical characteristics."
The fabrication of glass gels is relatively simple: researchers mix liquid precursors of the polymers with an ionic liquid, then expose the mixture to ultraviolet light to harden it. This easy process allows for cost-effective production of these materials, whether through molding or 3D printing.
Another major advantage of glass gels is their self-healing capability. In the event of a cut or break, a simple application of heat allows the material to heal. This property, combined with their high adhesiveness, makes these gels especially interesting for applications such as soft robotic grippers or medical devices.
The researchers, whose study was published in
Nature, tested various polymers and ionic liquids to create these gels, opening up a wide range of possible combinations to meet specific needs. Although not all classes of polymers are suitable, charged or polar ones seem particularly promising.
Thus, glass gels represent a significant advancement in the field of materials. Easy to produce, stretchable, self-repairing, and conductive, they offer considerable potential for many industrial and technological applications.
Article author: Cédric DEPOND