Comparative study of carbon nanotube dispersion using surfactants

• Published in: Journal of colloid and interface science Vol. 328; no. 2; pp. 421 - 428
• Main Authors: Rastogi, Richa, Kaushal, Rahul, Tripathi, S.K., Sharma, Amit L., Kaur, Inderpreet, Bharadwaj, Lalit M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 15-12-2008; Elsevier
• Subjects: Absorbance; Chemistry; Colloidal state and disperse state; Dispersion; Exact sciences and technology; Flocculation; General and physical chemistry; Models, Chemical; Molecular Weight; Multiwalled nanotubes; Nanotubes, Carbon - chemistry; Particle Size; Surface physical chemistry; Surface-Active Agents - chemistry; Surfactants; Absorbance; Multiwalled nanotubes; Surfactants; Dispersion; Stability; Non ionic surfactant; Device; Chemical structure; Carbon nanotubes; Dispersing power; Surfactant; Ionic surfactant; Mechanism; Lauryl sulfate; Anionic surfactant; Transmission electron microscopy; Multiwalled nanotube; Sodium sulfate; Comparative study; Ultraviolet visible spectrometry
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2008.09.015

Dispersion of carbon nanotubes (CNTs) is a challenging task for their utilization in nanoscale device applications. This account reports a comparative analysis on dispersion of multiwalled carbon nanotubes (MWNTs) with four surfactants—Triton X-100, Tween 20, Tween 80, and sodium dodecyl sulfate (SDS). Among the four surfactants, Triton X-100 and SDS provide maximum and minimum dispersion, respectively. Dispersion of MWNTs has been characterized with UV–vis spectroscopy and transmission electron microscopy (TEM). TEM results are in agreement with the UV–vis measurements. The experimentally observed trend of dispersing power of surfactants is consistent with their chemical structures. An optimum CNT-to-surfactant ratio has been determined for each surfactant. This parameter is shown to affect the nanotube dispersion significantly. Surfactant concentration above or below this ratio is shown to deteriorate the quality of nanotube dispersion. TEM analysis of a high-surfactant-concentration sample enables us to construct a plausible mechanism for decrease in CNT dispersion at high surfactant concentration, consistent with the UV–vis observations. Temperature stability of the surfactant is another important factor affecting the quality of CNT dispersion.
Optimum CNT-to-surfactant ratio is the most important parameter affecting nanotube dispersion using surfactant. Dispersion also decreases at high surfactant concentrations due to flocculation of CNTs via extra surfactant molecules.