SDBS sodium dodecyl benzene sulfate

SDBS Sodium dodecyl benzene sulfate 348 Anionic... 

SDBS sodium dodecyl benzene sulfonate NaLS sodium lauryl sulfate Wq [H20]/[surfactant]... 

Surfactants — either anionic surfactants such as sodium dodecylsulfate [SDS], or sodium dodecyl benzene sulfate [SDBS], or polysaccharide [Gum Arabic GA] — were first used to disperse, and exfoliate as-produced SWCNTs in water by ultrasonication, and to stabilize the resulting aqueous CNT suspension, see Figure 2.12. The SWCNTs were synthesized by either the AD method [about 30 % of impurities], or by the HiPCO process [having a catalyst particle content of about 5 wt%]. Please note that not only short surfactant molecules, but also polymeric surfactants such as polystyrene sulfonate, or even conductive polymers having a surfactant nature, can also be successfully used to disperse CNTs in water. 

Use of surfactants is an effective way for dispersing CNTs [39]. Reports show that the outer most nanotubes in a bundle are treated more than the innermost tubes and the nanotube remains predominantly btmdled even after surfactant treatment. But mechanical methods like ultrasonication can debundle the nanotubes by steric or electrostatic repulsions [40]. On sonication the high local shear will unravel the outer carbon nanotubes in a bundle and expose other sites for additional surfactant adsorption, thus the surfactant molecules gradually exfoliate the bundle in an unzippering mechanism [41]. Some of the common surfactants used for the dispersion of carbon nanotubes are sodium dodecyl benzene sulfonate (SDBS) [42], dodecyl trimethyl ammonium bromide (DTAB) [43], hexadecyl trimethyl ammonium bromide (CTAB) [44], octylphenol ethoxylate (Triton X-100) [45] and sodium dodecyl sulfate (SDS) [46]. Covalent modification is another way to solubilize the CNTs in different solvents and to improve the interaction with the matrix in composites [47]. 

Surfactants are those molecules that comprise both hydrophilic and hydrophobic groups simultaneously. The hydrophilic groups can be either ionic (e.g., -SOj, -SO3, -COOH, and -N(CHsIj) or nonionic (e.g., -0-(CH2-CH2-0) -H). As to the hydrophobic groups, the most widely used ones are the alkyl chains (-C H2 +i) and arakyl chains (-C H2 +i-C6H4-). Representative surfactants include anionic sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), sodium bis(2-ethylhexyl) sulfosuccinate, sodium stearate, cationic hexadecyltrimethylammonium bromide, and nonionic i-octophenol polyethoxylate with an average of 40 monomeric units of ethylene oxide per molecule. Such amphoteric species tend to diffuse toward the interface between the oily and aqueous phases and reside therein. 

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