The scientific community has long been interested in boron nitride because of its unique properties - it is strong, ultrathin, transparent, insulating, lightweight and thermally conductive - which, in theory, makes it a perfect material for use by engineers in a wide variety of applications. However, boron nitride's natural resistance to chemicals and lack of surface-level molecular binding sites have made it difficult for the material to interface with other materials used in these applications.
Associate Professor Vikas Berry and his colleagues from UIC are the first to report that treatment with a superacid causes boron nitride layers to separate into atomically thick sheets, while creating binding sites on the surface of these sheets that provide opportunities to interface with nanoparticles, molecules and other 2D nanomaterials, like graphene. This includes nanotechnologies that use boron nitride to insulate nano-circuits.
"Boron nitride is like a stack of highly sticky papers in a ream, and by treating this ream with chlorosulfonic acid, we introduced positive charges on the boron nitride layers that caused the sheets to repel each other and separate," said Assoc Prof. Berry.
He explains that "like magnets of the same polarity," these positively charged boron nitride sheets repel one another.
"We showed that the positive charges on the surfaces of the separated boron nitride sheets make it more chemically active," he continues. "The protonation - the addition of positive charges to atoms - of internal and edge nitrogen atoms creates a scaffold to which other materials can bind."
The opportunities for boron nitride to improve composite materials in next-generation applications are vast, Assoc Prof. Berry adds.
"Boron and nitrogen are on the left and the right of carbon on the periodic table and therefore, boron-nitride is isostructural and isoelectronic to carbon-based graphene, which is considered a 'wonder material,'" he says. This means these two materials are similar in their atomic crystal structure (isostructural) and their overall electron density (isoelectric).
The team believe this material could be used in all kinds of electronics including optoelectronic and piezoelectric devices, as well as applications like medical diagnostic devices.
