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The effect of pH and ionic strength on the dispersion of carbon nanotubes in poly(acrylic acid) solutions
Author(s) -
Shieh YeongTarng,
Chen JinYu,
Twu YawoKuo,
Chen WenJang
Publication year - 2012
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.3203
Subject(s) - dispersion (optics) , carbon nanotube , acrylic acid , aqueous solution , ionic strength , zeta potential , materials science , chemical engineering , ionic bonding , scanning electron microscope , chemistry , inorganic chemistry , nuclear chemistry , composite material , nanotechnology , nanoparticle , copolymer , organic chemistry , polymer , ion , optics , physics , engineering
The dispersion of three kinds of acid‐treated carbon nanotubes (CNTs) in poly(acrylic acid) (PAA) aqueous solution of different pH and ionic strengths (varied by NaCl, KCl and ZnCl 2 ) was investigated by visual observation, zeta potential, particle size analysis, transmission electron microscopy and scanning electron microscopy. Visual observation revealed that the dispersion of CNTs acid treated at 60 °C for 3 h and at 80 °C for 2 h was poor in aqueous solutions with pH < 2 or pH > 12. The poor dispersion of acid‐treated CNTs may be improved by adding PAA. In particular, PAA improved the dispersion of CNTs with greater COOH content. In a low pH solution (pH 1.5), a higher PAA content resulted in poorer CNT dispersion while in a high pH solution (pH 12.5), a higher PAA content led to better CNT dispersion. For superior dispersion in a basic aqueous solution (pH 12.5), experimental data showed that a greater atomic radius or a higher cationic charge of the added salt may result in faster aggregation and thus precipitation of CNTs. Copyright © 2011 Society of Chemical Industry