Aligning of single walled carbon nanotubes using a pH responsive poly (acrylic acid) as a surfactant
Aligning of single walled carbon nanotubes has been shown to significantly enhance electrical and mechanical properties in polymer composites. Here, we report a novel method of using Poly (acrylic acid) a pH responsive polymer that is known to control the stability and dispersion of single-walled carbon nanotubes (SWNTs) in aqueous solutions to stabilize the SWNTs and align them using an AC electric field. Tuning the pH of the PAA suspended solution changes the microstructure of the SWNTs from an intercalated state to an exfoliated state. Good dispersion and stability of the SWNTs was achieved at low pH as opposed to high pH. Applying an AC electric field led to good alignment and chain formation of SWNTs in the direction of the applied field. The pH of the solution and PAA concentration play a significant role in achieving good dispersion, alignment and chain formation. Electrical conductivity of the solutions as a function of microstructure was studied. Improvement in electrical conductivity with increase in frequency was observed. Future work will focus on further probing the effect of pH and PAA content, and conserving the achieved microstructures to process solid composite films. Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
author list (cited authors)
Kalidindi, S., Ounaies, Z., Lui, L., & Grunlan, J.