Glassy polymers, which are used to make airplane windows, are very strong and hard materials but also very brittle. For that reason, they still have a limited use. Now, though, there is a new class of material called a “glassy gel,” which retains the properties of glass polymers while introducing flexibility, similar to gels.
During regular use, glassy gels can retain their shape, but when enough force is applied, they will start to stretch, almost five times their original length. Furthermore, glassy gels can return to their original form once heat is applied, and they are also very sticky and have self-healing properties. The best part is that glassy gels are mostly made from ionic liquid, making them excellent electrical conductors. Therefore, these glassy gels created by engineers at the North Carolina State University (NCSU) could potentially be used to manufacture highly efficient electrical conductors, medical implants, or electrical devices.
The team of engineers created the glassy gel material by combining a glassy polymer with an ionic liquid, which was then poured into a mold and cured with UV light. “In glassy gels, the solvent pushes the molecular chains in the polymer apart, which allows it to be stretchable like a gel,” says Michael Dickey, professor of chemical and biomolecular engineering at North Carolina State University.
“However, the ions in the solvent are strongly attracted to the polymer, which prevents the polymer chains from moving. The inability of chains to move is what makes it glassy. The end result is that the material is hard due to the attractive forces but is still capable of stretching due to the extra spacing.” The resulting material contains 54% liquid yet also has a fracture strength of 42 MPa, yield strength of 73 MPa, and toughness of toughness of 110 MJ m-3. Crucially, glassy gels are very easy to make when manufacturing at scale. Moreover, the team suggests that glassy gels can be 3D-printed, which could have huge implications for their use in various industries.
Image Credit: Meixiang Wang via NC State University
Original Study: nature.com
