  A computational investigation was carried out to understand the aggregation
of nanoscale graphene with two typical assembly pathways of stacking assembly
and sliding assembly in water. The interfacial-organized monolayer water film
(MWF) hindering the aggregation of nanographene in both stacking and sliding
assembly pathways was reported for the first time. By means of potential mean
forces (PMFs) calculation, no energy barrier was observed during the sliding
assembly of two graphene nanosheets, while the PMF profiles could be impacted
by the contact forms of nanographene and the MWF within the interplate of two
graphene nanosheets. To explore the potential physical basis of the
hindering-role of self-organized interfacial water, the dynamical and
structural properties as well as the status of hydrogen bonds (H-bonds) for
interfacial water were investigated. We found that the compact, ordered
structure and abundant H-bonds of the MWF could be taken as the fundamental
aspects of the hindering-role of interfacial water for the hydrophobic assembly
of nanographene. These findings are displaying a potential to further
understand the hydrophobic assembly which mostly dominate the behaviors of
nanomaterials, proteins etc. in aqueous solutions.
