Tuesday February 12, 2019

Laser-Induced Graphene Gains Strength as a Composite

Researchers at Rice University discovered how to make graphene with a laser in 2014. Laser-induced graphene is a flaky foam of the atom-thick carbon that can be combined with other materials to form robust composites. LIG is far cheaper to make than using traditional chemical vapor deposition (CVD) to make graphene and the laser method creates far more of the material than CVD.

LIG has one undesirable property; it flakes off when a person runs their hand across it. By pouring a second liquid material over the LIG attached to a polyimide (common plastic), the LIG will form a composite and the polyimide layer can be peeled off. The new composite gives the LIG new strength and the material can be used to create deicers, wearable electronics and more. Some fabric composites and cement will absorb water and LIG combined into a composite with a harder material will create a hydrophobic material. Both are shown in the following videos.

Soft composites can be used for active electronics in flexible clothing, Tour said, while harder composites make excellent superhydrophobic (water-avoiding) materials. When a voltage is applied, the 20-micron-thick layer of LIG kills bacteria on the surface, making toughened versions of the material suitable for antibacterial applications. Composites made with liquid additives are best at preserving LIG flakes' connectivity. In the lab, they heated quickly and reliably when voltage was applied. That should give the material potential use as a deicing or anti-icing coating, as a flexible heating pad for treating injuries or in garments that heat up on demand. "You just pour it in, and now you transfer all the beautiful aspects of LIG into a material that's highly robust," Tour said.