Separating Single-Walled Carbon Nanotubes by Length

摘要

Single-walled carbon nanotubes (SWNTs) are typically microns in length. However, intermediate lengths between small spheroidal fullerenes and long SWNTs could have significant scientific and technological importance in molecular electronics and sensing applications. Existing methods are limited by factors such as scalability, polydispersity and cost. Here we describe a simple, yet powerful technique for sorting SWNTs by length. It is based on a scalable two-phase liquid-liquid extraction process which is capable of transferring water-soluble SWNTs into an organic phase. The extraction utilizes electrostatic interactions between a common phase transfer agent and the sidewall functional groups on the nanotubes. Large length-dependent van der Waals forces for nanotubes allow the ability to control the length of nanotubes extracted into the organic phase as demonstrated by AFM.