(346e) Ultra-Highly Conductive, Strong, Lightweight Fibers of Carbon Nanotubes by Scalable Processing

Since their discovery 20 years ago, carbon nanotubes (CNTs) have held great, yet unfulfilled, promise for lightweight multifunctional materials. A long held tenet is that useful mechanical strength and electrical conductivity can be attained only with very long CNTs (~mm).  Such requirement limits severely potential applications, because of poor scalability of growth and processing of long CNTs.  Here we report high-performance fibers of short, bulk-grown CNTs (below 10 µm) produced by industrially scalable wet spinning.  The spinning process is similar of that of PPTA, i.e., Kevlar and Twaron.  The CNTs are dissolved in a strong acid to form a liquid crystalline dope; the liquid crystalline dope is spun into a coagulant bath to form a solid fiber, which is wound on a rotating drum.  These fibers combine the specific strength and stiffness of carbon fibers to the specific electrical conductivity of metals. The specific thermal conductivity of these CNT fibers exceeds that of metals and rivals the specific thermal conductivity of the best pitch-based carbon fibers. This combination of properties and processing defines a new area of material design.