Effect of degassing on the aggregation of carbon nanotubes dispersed in water

¹ Institute of Physics, Academia Sinica - Nangang, Taipei 115, Taiwan
² Department of Physics, National Taiwan Normal University - Wenshan, Taipei 116, Taiwan
³ Department of Polymer Science and Engineering, Inha University - Incheon 402-751, Korea
⁴ Department of Physics and Center for Complex Systems, National Central University - Chung-Li, Taoyuan 320, Taiwan

^(a) ajrhuang@gate.sinica.edu.tw (corresponding author)
^(b) ckchan@gate.sinica.edu.tw (corresponding author)

Received: 30 March 2017
Accepted: 6 December 2017

Abstract

Dynamic light scattering (DLS) along with centrifugation and shaking tests reveal that dissolved gases can significantly affect the aggregation behavior of carbon nanotubes (CNTs) dispersed in water. The CNTs in non-degassed samples form loose, stable networks having the DLS result reminiscent of semidilute polymer solutions, whereas the CNTs in degassed samples aggregate to form Brownian colloids that sediment quickly. Interestingly, the CNTs dispersed in acetone, with or without degassing, also behave like semidilute polymers in DLS experiments. We propose a surface nanobubble-assisted mechanism to explain the observed aggregation behaviors. Our work signifies that dissolved gases may play an important role in determining hydrophobicity and biomolecular functions in aqueous environments.