The proliferation and miniaturization of electronics in devices, wearables, medical implants, and other applications has made technologies for blocking electromagnetic interference (EMI) especially important, while making their implementation more challenging. EMI can cause disruptions in communication in critical applications, resulting in potentially disastrous consequences, however traditional EMI shields need to be very thick to be effective, hampering design flexibility.
One solution resides in MXenes, a family of 2D transition metal carbides, nitrides, and carbonitrides that demonstrate high conductivity and excellent EMI shielding properties. The key to the commercialization of these materials is industrial-scale manufacturing.
A multi-institution research team led by André D. Taylor, professor of chemical and biomolecular engineering at the NYU Tandon School of Engineering, demonstrated a novel approach to MXene fabrication that could lead to methods for at-scale production of MXene freestanding films: drop-casting onto prepatterned hydrophobic substrates. Their method led to a 38% enhancement of EMI shielding efficiency over conventional methods.
The team cast aqueous dispersions of MXene nanosheets (Ti3C2Tx) on hydrophobic polystyrene substrates and dried them. After drying, the resulting free-standing films could be easily peeled off, a method demonstrating a variety of advantages over the conventional vacuum-assisted filtration method with regards to time efficiency, operation simplicity, and surface smoothness.
Taylor said the beauty of the drop-casting method lies in its ability to allow for modulation of micrometer-scale 3D patterns on the film surface by utilizing pre-patterned substrates (such as a vinyl record, retroreflective packaging, and retroreflective tape). He added that the research leads toward more sustainable production. A critical benefit of the process is that it allows for better control of the thin film configuration of the Ti3C2Tx (including the lateral size and the thickness).
“The conventional wisdom for making MXene films is that you should match a hydrophilic material with a hydrophilic substrate to get a smooth coating,” said researcher Jason Lipton. “We found that if you instead try to use a hydrophobic surface it results in simple, scalable production of freestanding films because the MXenes would rather stick together than interact with the surface. Because there are many commercially available microstructured plastics, there are a lot of options for making a 3D-patterned MXene film, and we find that choosing the right pattern can dramatically improve its EMI shielding effectiveness. This opens up a lot of opportunities to study different micro-structured MXene composites for wide-ranging applications.”
“This proof of concept marks an essential step towards the massive production of Ti3C2Tx films, which opens a bright venue to accelerate the commercialization of MXene products,” added Taylor.