A team of scientists from North Carolina State University and China’s Suzhou Institute of Nano-Science and Nano-Biotics have been working together on a new technique. Microcombing is an inexpensive process which leads to better alignment of carbon nanotubes (CNTs), improving the properties of CNT films, writes Matt Shipman on RDMag.com.

Microcombing
Image credit: Yuntian Zhu

Microcombing untangles CNT ribbons

The new microcombing technique is inexpensive and creates stronger CNT films than before, as well as improving their conductivity to levels which make them attractive to electronic and aerospace companies.

“It’s a simple process and can create a lightweight CNT film, or ‘bucky paper,’ that is a meter wide and twice as strong as previous such films—it’s even stronger than CNT fibers,” says Yuntian Zhu, Distinguished Professor of Materials Science and Engineering at NC State, who wrote a paper describing the work.

The first stage of the process saw scientists grow the CNTs on a normal substrate with a closely packed array. The fact that the CNTs are tangled means that when the team pull on one end, the CNTs form a continuous ribbon. The ribbon, which is only a nanometers thick, is then attached to spool and wound up.

Searching for industrial partners

The spool pulls the CNT ribbon between two surgical blades, both of which feature micrometer-scale fissures on their cutting edge. The effect of these fissures is to create a so-called “microcomb” which aligns the CNTs in much the same way that a comb pulls tangled hair into line.

The application of an alcohol solution during this process brings the CNTs closer together and strengthens the bonds between them. Microcombing makes CNT films which have over twice the tensile strength of uncombed films, as well as having 80% higher electrical conductivity.

“This is a significant advance, but we want to find ways to make CNT alignment even straighter,” said Zhu. “It’s still not perfect. “In addition, the technique would theoretically be easy to scale up for large-scale production. We’d like to find an industry partner to help us scale this up and create a material for the marketplace.”