Graphene fibre has potential applications in diverse technological areas, from energy storage, electronics and optics, electro-magnetics, thermal conductor and thermal management, to structural applications.
A team of researchers at Rensselaer Polytechnic Institute has developed a new microfluidics-assisted technique for developing high-performance macroscopic graphene fibres. Graphene fibre, a recently discovered member of the carbon fibre family, has potential applications in diverse technological areas, from energy storage, electronics and optics, electro-magnetics, thermal conductor and thermal management, to structural applications.
Their findings are published in a newly released issue of Nature Nanotechnology. It has historically been difficult to simultaneously optimise both the thermal/electrical and the mechanical properties of graphene fibres. However, the Rensselaer team has demonstrated their ability to do both.
Macroscopic graphene fibre can be manufactured by fluidics-enabled assembly from 2D graphene oxide sheets dispersed in aqueous solutions forming lyotropic liquid crystal. Strong shape and size confinements are demonstrated for fine control of the graphene sheet alignment and orientation, critical for realizing graphene fibers with high thermal, electrical, and mechanical properties. This microfluidics-enabled assembly method also provides the flexibility to tailor the microstructures of the graphene fibres by controlling flow patterns.
The image shows “Sheet alignment and orientation order of graphene structures induced by microfluidics design enable the microstructure control and optimization of thermal-mechanical and electronic properties of macroscopic graphene fibers.”
Abstract from Nature Nanotechnology.
Macroscopic graphene structures such as graphene papers and fibres can be manufactured from individual two-dimensional graphene oxide sheets by a fluidics-enabled assembling process. However, achieving high thermal-mechanical and electrical properties is still challenging due to non-optimized microstructures and morphology. Here, we report graphene structures with tunable graphene sheet alignment and orientation, obtained via microfluidic design, enabling strong size and geometry confinements and control over flow patterns. Thin flat channels can be used to fabricate macroscopic graphene structures with perfectly stacked sheets that exhibit superior thermal and electrical conductivities and improved mechanical strength. We attribute the observed shape and size confinements to the flat distribution of shear stress from the anisotropic microchannel walls and the enhanced shear thinning degree of large graphene oxide sheets in solution. Elongational and step expansion flows are created to produce large-scale graphene tubes and rods with horizontally and perpendicularly aligned graphene sheets by tuning the elongational and extensional shear rates, respectively.