Texas researchers develop mechanically robust conductive coating

Wearable devices are all the rage these days. Engineers are looking for new ways to integrate the latest tech such as adaptive displays, artificial skins and biometric devices into the latest projects.

A College of Engineering at Texas A&M University research team has developed a mechanically robust conductive coating that maintains performance under heavy stretching and bending. Developing stretchable, bendable and foldable electronics is key to the development of the latest aforementioned tech.

Balancing electronic performance and mechanical flexibility was a significant challenge for the team. Finding the right material that is able to withstand extreme pressures of deformation while maintaining electrical conductivity was crucial for the team. The material also needed to be engineered in such a way that it would be conductive in a variety of different surfaces, such as cloth, fiber, glass or plastic.

A group from the Artie McFerrin Department of Chemical Engineering and the Department of Materials Science and Engineering led by Dr. Jodie Lutkenhaus, associate professor and holder of the William and Ruth Neely Faculty Fellowship, took up the challenge.

The team developed a new surface-agnostic stretchable, bendable and foldable conductive coating, opening the door for a wide variety of flexible electronics.

Structural and morphological characterizations of MXene multilayers. (A) Schematic of the PDAC/MXene LbL assembly process. Images of (B) immersion AQ48 and (C) spray assembly of multilayer coatings of varying number of layer pairs on glass. (D) A cross-sectional scanning electron microscopy (SEM) image of the mulAQ49 tilayer coating. (E) Ultraviolet-visible (UV-vis) spectra of MXene multilayers on glass. (F) Absorbance values at 770 nm versus number of layer pairs. a.u., arbitrary units. AQ50 (G) Growth profile of the multilayers on glass. (H) Root-mean-square (RMS) roughness versus number of layer pairs. (Image courtesy of H. An, T. Habib, S. Shah, H. Gao, M. Radovic, M. J. Green, J. L. Lutkenhaus)

Two-dimensional metal carbides (MXenes) were chosen as the main focus of the research as previous research has shown them to have a metallic-like conductivity. The previous research on MXenes has focused primarily on the materials in the form of sheets. Although these sheets have the desired conductivity, they are not stretchable and their integration into different surfaces has not been shown.

Rather than using MXene sheets, the Texas A&M research team created MXene coatings through the sequential adsorption of negatively charged MXene sheets and positively charged polyelectrolytes using an aqueous assembly process known as layer-by-layer (LbL) assembly. In doing this, the team was able to demonstrate that MXene multilayer coatings that can undergo large-scale mechanical deformation while maintaining a high level of conductivity.

They were also successfully deposited the MXene multilayer coatings onto flexible polymer sheet, stretchable silicones, nylon fiber, glass and silicon.

The results are described in the latest issue of Science Advances.

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