Tunable single-walled carbon nanotube microstructure in the liquid and solid states using poly(acrylic acid)
Jaime C Grunlan1, Lei Liu, Yeon Seok Kim
1Department of Mechanical Engineering, Polymer Technology Center, Texas A and M University, College Station, Texas 77843-3123, USA. jgrunlan@tamu.edu
Nano Letters
|May 11, 2006
Summary
Poly(acrylic acid) controls single-walled carbon nanotube (SWNT) dispersion and viscosity in aqueous solutions. Adjusting pH alters SWNT aggregation, impacting composite properties and conductivity.
Area of Science:
- Materials Science
- Polymer Chemistry
- Nanotechnology
Background:
- Single-walled carbon nanotubes (SWNTs) possess unique properties but face challenges in achieving stable dispersions.
- Poly(acrylic acid) (PAA) is a water-soluble polymer with potential applications in stabilizing nanomaterials.
Purpose of the Study:
- To investigate the role of poly(acrylic acid) in controlling the dispersion state of SWNTs in aqueous mixtures.
- To explore the influence of pH on SWNT aggregation and the resulting properties of PAA-SWNT composites.
Main Methods:
- Utilized poly(acrylic acid) as a stabilizing agent for SWNTs in aqueous suspensions.
- Varied the pH of the PAA-SWNT mixtures to study dispersion changes.
- Employed electron microscopy and electrical conductivity measurements to characterize SWNT microstructure and composite properties.
Main Results:
- PAA effectively controlled SWNT dispersion levels in both liquid and solid composite states.
- At low pH, PAA-SWNT suspensions exhibited water-like viscosity, which increased with rising pH.
- Reversing the pH change restored the initial low viscosity, indicating reversible aggregation/exfoliation of SWNTs.
Conclusions:
- Poly(acrylic acid) acts as a pH-responsive dispersant for SWNTs.
- pH-induced changes in SWNT microstructure significantly affect the rheological and electrical properties of PAA-SWNT composites.
- This pH-tunable dispersion offers a pathway for controlled fabrication of SWNT-based materials.
