It turns out the wrinkles and crumples don't destroy everything after all. Scientists have found that repeatedly crumpling sheets of graphene can actually enhance some of its properties rather than destroying it.
In this latest study, the scientists built on previous research that showed that wrinkled graphene could be used as substrates for culturing cells. In fact, these substrates were far more similar to the complex environments in which cells grow in the body. Knowing this, the researchers in this latest study wanted to build even more complex architectures using both wrinkles and crumples.
The researchers deposited layers of graphene oxide onto polymer membranes. These membranes shrink when heated. In this case, when they shrunk, the graphene on top was compressed; this, in turn, caused the graphene to wrinkle and crumple. The researchers did this same step multiple times with the same graphene sheets to see what kind of structures they could create.
So what did they find? It turns out that crumpling the sheet multiple times could substantially compress the graphene sheets. In fact, some sheets wound up being as small as one-fortieth of their size. Some graphene sheets also wound up with wrinkles and crumples that were superimposed onto each other.
"As you go deeper into the generations you tend to get larger wavelength structures with the original, smaller wavelength structure from earlier generations built into them," said Robert Hurt, one of the researchers.
But how were the graphene sheets impacted? The researchers then tested several structures to see how they altered the properties of the graphene sheets. This revealed that a highly crumpled graphene surface became superhydrophobic, which means that it resisted water. With different techniques to create different wrinkles, the researchers found that the graphene's electrochemical behaviors were enhanced. This could be especially useful in next-generation energy storage and generation.
"You don't need a new material to do it," said Po-Yen Chen, one of the researchers. "You just need to crumple the graphene."
The findings reveal that just by changing the shape of graphene, researchers can enhance its properties. This could be huge for future use when it comes to electronics and other material uses.
The findings are published in the March 2016 journal Advanced Materials.
