Thinning of glycerol in the presence of multi-walled carbon nanotubes

Hydrogen bonding is an important index to determine the viscosity of liquids containing a hydroxyl group. The change of hydrogen bond must change the viscosity of liquid. Glycerol is a kind of polyhydroxy high viscosity liquid. The rheological property is one of the biggest concerns for glycerol. Reduction of glycerol viscosity without diluting or heating to change its hydrogen bonding is considered to be challenging. Here, we demonstrate the effect of multiwalled carbon nanotubes (MWNTs) on the thinning of glycerol. The viscosity of glycerol was decreased at certain proportions, with a viscosity reduction range of 0.54%–1.17%. The hydrogen bond network was broken by the adsorption and space-limiting effect of MWNTs. Transmission electron microscopy and computer simulation results showed that glycerol molecular clusters were mainly dispersed on the surface of MWNTs and adsorbed into the internal pipe of MWNTs. A cavity between the glycerol molecules and MWNTs performed the space-limiting role of MWNTs. MWNTs simultaneously acted as a viscosifier and viscosity reducer. These two effects show a competitive relationship with the amount of additional changes. We expect these results to provide a new perspective in controlling rheological behavior and reveal the underlying interaction between hydroxy liquids and nanomaterials.