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Dispersing Carbon Nanotubes in Aqueous Solutions of Trisiloxane‐Based Surfactants Modified by Ethoxy and Propoxy Groups
Author(s) -
Xin Xia,
Pang Jinyu,
Li Wenzhe,
Wang Yitong,
Yuan Jing,
Xu Guiying
Publication year - 2015
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-014-1636-8
Subject(s) - siloxane , dispersant , carbon nanotube , silicone , pulmonary surfactant , chemistry , aqueous solution , chemical engineering , ethylene oxide , van der waals force , adsorption , hydrophobic effect , intermolecular force , dispersion (optics) , octamethylcyclotetrasiloxane , polymer chemistry , materials science , organic chemistry , composite material , polymer , molecule , copolymer , biochemistry , physics , optics , engineering
Silicone surfactants favor spreading at interfaces and siloxane has strong interaction with carbon nanotubes (CNT), thus silicone surfactant may be a good dispersant of CNT. Here, four silicone surfactants (named S1E19, S2E38, S2E16 and S1E16P8) were used to disperse CNT in aqueous solutions. The effects of surfactant structure and concentration on the ability at dispersing CNT were considered. All of the four silicone surfactants can disperse CNT in aqueous solution and the sample with 1,000 mg L −1 S1E16P8 was the best one. The hydrophilic group polyoxyethylene (PEO) and the hydrophobic groups siloxane and polypropylene (PPO) are crucial factors in the ability of dispersing CNT. S2E38 with more ethylene oxide (EO) groups has a stronger ability to disperse CNT than S2E16. The dispersion system provided by S1E19 which contains fewer siloxane and EO groups is relatively unstable and disperses less CNT. These experimental results are explained by molecular dynamics simulation. S2E38 compared with S1E19 and S2E16 has stronger interactions with CNT. The interaction energy of CNT with S1E16P8 which has a PPO moiety but fewer siloxane groups is close to that of S2E16. Furthermore, it can be concluded that these four surfactants are adsorbed on CNT mainly by van der Waals forces and the Si–O–Si chain of silicon surfactant was flexible due to the long Si–C bond and it could easily wrap onto the surface of CNT through hydrophobic and other intermolecular interactions. The hydrophilic part of PEO helped the CNT dispersed in the aqueous solution and prevented CNT from aggregating in water through steric stabilization.