I have read that carbon nanotubes are highly polarizable, but they are hydrophobic. Why are they hydrophobic?
Carbon is hydrophobic isngeneral unless it has been functionalized with polar moieties. Oxidation is the easiest of such fuctionalization, making the carbonaceous support much more hydrophylic. But in the absence of such surface functions, carbon is almost purely based on aromatic, non-polar, sheets, so that interaction with extremely polar molecules such as water is very weak.
Alain
Also note that high polarizability supposes low polarity, and vice-versa. Pure carbon being intrinsically non polar is polarizable. After functionalization, polarity increases much, and therefore the material is not so polarizable.
Alain
I do agree with the above statements and the explanation by Alain more detailed. Carbons are hydrophilc at least initially. However, with time the contact angle changes showing wettability and depending on the electrolyte used. One can change the hydrophobic nature by oxidation using acids and gases with thermal treatment.
@Alain
"high polarizability supposes low polarity, and vice-versa"- really nonsense.Sorry :-) Hydrocarbons ( like hexane) and perfluorocarbons (like perfluorohexane) are both most non-polar and hard polarizable compouds.
@All
About CNT hydrohpobicity : http://filebox.vt.edu/p/patlaf/Research/CNT%20Papers/9-WaltherJaffeHalicioglu.pdf http://pubs.acs.org/doi/abs/10.1021/jp011344u
However, non-polar CNT are soluble in very strong acids like 100% H2SO4 : US 7,125,502 - like graphite that build "graphite salt"
What is the application of the water contact angle of single-wall carbon nanotubes based flexible electrodes in rechargeable LIBs? how does the hydrophobic or hydrophilic nature of the single-wall carbon nano-tubes based electrodes effect the electrochemical performances@Alain Celzard
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