Dispersion of nano tubes of carbon in liquid (CNT) whether organic or aqueous is the key to coatings by EPD method or spin coating. The multiwall CNT (MWCNT) was bought from US research Nanomaterials Inc. The specification of this product follows. More info can be found on www.us-nano.com.

Purity: > 95 wt%               

Outside diameter: 50-80 nm 

Inside diameter: 5-15 nm

Length: 10-20 um 

(TEM)SSA: > 40 m²/g

Color: Black

%Ash: <1.5 wt

Electrical conductivity: >100 s/cmTap 

Tap density: 0.18 g/cm³

True density: ~2.1 g/cm³

Manufacturing Method: CVD

As the first experience, the several milligrams of the aforementioned MWCNT was poured on the beaker filled with DI water. As the below image suggests, no apparent dispersion was observed. It seems that MWCNT floats the DI water and no tendency to coagulation can be observed.

The same e experience was done using the isopropyl alcohol (IPA) and the same result was observed.

As next experiment, ethanol (C2H5OH) was used to disperse the MWCNT but only the same result was observed.

As for both the IPA and ethanol only coagulation of MWCNT can be observed and no sign of liquid inclination to disperse the MWCNT was observed. And the same experience was performed using paint thinner and the results follows.

The same result went for using paint thinner. As the last attempt to disperse the MWCNT, a little MWCNT was poured on the DI water and a smattering of Sodium lauryl sulfate (SLS) was applied. The result was amazing. SLS is a surfactant which has a hydrophobic (water-hating) tail and a hydrophilic (water-loving) head. It means that it can help disperse the MWCNT in the DI water.