In plain words
The biggest market for so far: of graphene or other layered materials mixed in small amounts into plastics, rubber, concrete, paints or , to make them stiffer, tougher, more conductive or less permeable. Sold by the tonne, these products use cheap flakes made in bulk rather than perfect . Whether a few percent of flakes really helps depends on how well they are spread out, how they line up and how firmly they hold on to the material around them.
Going deeper
How a little helps
A flake is stiff, strong and – for graphene – conductive along its whole width, and a gram of thin flakes has a surface of hundreds of square metres. Spread through a plastic, flakes carry part of the load, deflect cracks and, once there are enough of them to touch, form a continuous conducting network. Because flakes are wide and thin, that happens at very low loadings: the first graphene–polystyrene composites began to conduct with about 0.1 percent of graphene by volume.
The same shape makes good barriers. Flakes lying flat in a coating force water, oxygen or salt ions to wind their way around them, lengthening their path many times over, which slows corrosion and the spoiling of packaged goods.
Where they are used
These are the applications already sold by the tonne: graphene in sports equipment, tyres, concrete and anti-corrosion paints; flakes as conductive additives in lithium-ion battery electrodes; hBN in thermally conductive fillers; coatings that shield electronics from . They use flakes produced in bulk by or from graphene oxide, not the pristine monolayers of research.
The gains are often modest and the competition is mature: carbon black, carbon fibres, talc and glass flakes are cheap and well understood. The products that succeed are those in which a small amount of flakes improves a property that matters, at a price the market accepts.
What makes or breaks it
Most disappointing results trace back to the flakes. Products sold as graphene range from single layers to graphite powder, so flake size, thickness and oxygen content should be measured rather than assumed. Flakes that restack into clumps behave like ordinary graphite; flakes that slip within the matrix carry no load; flakes lying at random make no barrier. Dispersion, alignment and the bond between flake and matrix decide the outcome at least as much as the flake itself – which is why international standards for describing graphene powders now matter to buyers.
For specialists
Bulk uses in which exfoliated or chemically derived flakes – graphene nanoplatelets, reduced graphene oxide, hBN, MXenes, clays – are dispersed in a matrix or applied as a film. In polymer composites a few weight percent can raise stiffness and toughness, cross the percolation threshold for electrical conduction – as low as about 0.1 percent by volume for thin, wide flakes – and raise ; aligned flakes in barrier coatings lengthen the diffusion path of water, oxygen and ions and slow corrosion; flakes used as conductive additives replace part of the carbon black in battery electrodes; MXene films give strong electromagnetic shielding. Performance depends on flake size and thickness, dispersion without restacking, alignment and bonding to the matrix, and on powders whose properties vary widely between suppliers.