SUPPLEMENTARY INFORMATION D0:10.1038/NMAT3228 parameters have been organized in Table 1.The contact angles of our samples do not exhibit system-size dependency once the size of the droplet is larger than 2000 molecules.The contact angle is around 1099.This value is close to the macroscopic contact angle 104 by Werder et al. Note that Werder's result might be biased by the smallest droplet,for which the contact angle has the largest uncertainty. Reference: 1.Werder,T.,Walther,J.H.,Jaffe,R.L.,Halicioglu,T.Koumoutsakos,P.On the Water-Carbon Interaction for Use in Molecular Dynamics Simulations of Graphite and Carbon Nanotubes.The Journal of Physical Chemistry B 107,1345-1352 (2003). 213AJ →X Figure S2:Side(top)and top view (bottom)of the snapshots for 4000 water molecules on double graphene layers.The dimensions are 393.5 A x 21.3 A x 200 A.Only part of the simulation system is shown.Blue,red and green dots are C,O and H atoms respectively NATURE MATERIALS www.nature.com/naturematerials 2012 Macmillan Publishers Limited.All rights reserved.parameters have been organized in Table 1. The contact angles of our samples do not exhibit system-size dependency once the size of the droplet is larger than 2000 molecules. The contact angle is around 109⁰. This value is close to the macroscopic contact angle 104⁰ by Werder et al1 . Note that Werder’s result might be biased by the smallest droplet, for which the contact angle has the largest uncertainty. Reference: 1. Werder, T., Walther, J.H., Jaffe, R.L., Halicioglu, T. & Koumoutsakos, P. On the Water−Carbon Interaction for Use in Molecular Dynamics Simulations of Graphite and Carbon Nanotubes. The Journal of Physical Chemistry B 107, 1345-1352 (2003). Figure S2: Side (top) and top view (bottom) of the snapshots for 4000 water molecules on double graphene layers. The dimensions are 393.5 Å × 21.3 Å × 200 Å. Only part of the simulation system is shown. Blue, red and green dots are C, O and H atoms respectively. 4 NATURE MATERIALS | www.nature.com/naturematerials SUPPLEMENTARY INFORMATION DOI: 10.1038/NMAT3228 © 2012 Macmillan Publishers Limited. All rights reserved