Graphene, a material stronger and stiffer than carbon fiber, has enormous commercial potential but has been impractical to employ on a large scale, with researchers limited to using small flakes of the material.
Now, using chemical vapor deposition, a team led by ORNL’s Ivan Vlassiouk has fabricated polymer composites containing 2-inch-by-2-inch sheets of the one-atom thick hexagonally arranged carbon atoms.
RNL’s ultrastrong graphene features layers of graphene and polymers and is an effective conductor of electricity.
The findings, reported in the journal Applied Materials & Interfaces, could help usher in a new era in flexible electronics and change the way this reinforcing material is viewed and ultimately used.
“Before our work, superb mechanical properties of graphene were shown at a micro scale,” said Vlassiouk, a member of ORNL’s Energy and Transportation Science Division. “We have extended this to a larger scale, which considerably extends the potential applications and market for graphene.”
While most approaches for polymer nanocomposition construction employ tiny flakes of graphene or other carbon nanomaterials that are difficult to disperse in the polymer, Vlassiouk’s team used larger sheets of graphene. This eliminates the flake dispersion and agglomeration problems and allows the material to better conduct electricity with less actual graphene in the polymer.
“In our case, we were able to use chemical vapor deposition to make a nanocomposite laminate that is electrically conductive with graphene loading that is 50 times less compared to current state-of-the-art samples,” Vlassiouk said. This is a key to making the material competitive on the market.
If Vlassiouk and his team can reduce the cost and demonstrate scalability, researchers envision graphene being used in aerospace (structural monitoring, flame-retardants, anti-icing, conductive), the automotive sector (catalysts, wear-resistant coatings), structural applications (self-cleaning coatings, temperature control materials), electronics (displays, printed electronics, thermal management), energy (photovoltaics, filtration, energy storage) and manufacturing (catalysts, barrier coatings, filtration).
Graphene is an ideal candidate for lightweight, high-strength composite materials given its superior mechanical properties (specific strength of 130 GPa and stiffness of 1 TPa). To date, easily scalable graphene-like materials in a form of separated flakes (exfoliated graphene, graphene oxide, and reduced graphene oxide) have been investigated as candidates for large-scale applications such as material reinforcement. These graphene-like materials do not fully exhibit all the capabilities of graphene in composite materials. In the current study, we show that macro (2 inch × 2 inch) graphene laminates and fibers can be produced using large continuous sheets of single-layer graphene grown by chemical vapor deposition. The resulting composite structures have potential to outperform the current state-of-the-art composite materials in both mechanical properties and electrical conductivities (over 8 S/cm with only 0.13% volumetric graphene loading and 5 × 10^3 S/cm for pure graphene fibers) with estimated graphene contributions of over 10 GPa in strength and 1 TPa in stiffness.
SOURCES – ORNL, Applied Materials and Interfaces