On the Validity of the Young-Laplace Equation for the Fluid Infiltration in Hydrophobic Nanochannels

We investigate the validity of the Young-Laplace equation by studying water infiltration into hydrophobic nanochannels through molecular dynamics simulations. At the nanoscale, it is found that the energy barrier at the channel entrance significantly raises the infiltration pressure and the classic Young-Laplace equation underestimates the infiltration pressure. As the channel surface is tuned from superhydrophobic to hydrophobic, the infiltration pressure is greatly reduced due to the decrease of capillary pressure (Young-Laplace equation) caused by the contact angle change, while the contribution of the entrance energy barrier to the infiltration pressure increases from 25% to 60%.