Facile fabrication of hydrophobic and underwater superoleophilic elastic and mechanical robust graphene/PDMS sponge for oil/water separation

A facile method for preparing hydrophobic and mechanical robust graphene/polydimethylsiloxane (PDMS) sponge is reported by embedding small amount of graphene onto the surface of PDMS sponge skeleton during mold transfer approach by using sugar cube as templates. The pore structures were completely transferred and surface embedding graphene resulted in the formation of layer-structure at the skeleton surface. Besides, the median pore diameter and porosity were slightly reduced after surface embedding with graphene while the total pore area increased 10% comparing with PDMS sponge. Graphene/PDMS sponge completely return to its original size after 100 cycles at the maximum strain of 80%. It only requires 0.4 MPa stress to reach 80% strain of graphene/PDMS sponge which is half the stress required to reach 80% strain of PDMS sponge. Surface embedding graphene significantly improved the elasticity and durability of PDMS sponge which solved the “trade-off” effect between mechanical compressibility and robustness by incorporation inorganic nanomaterials. The as-prepared graphene/PDMS sponge is highly hydrophobic and underwater superoleophobic which can quickly absorb oils underwater within 3.3 s while it took around 10 s for PDMS sponge to absorb the same amount oil. Graphene/PDMS sponge showed relatively stable oil absorption capacity after 15 absorption-desorption cycles and long-term continuously oil collecting performance by equipping with pump. The research findings might promote the development of mechanical robust and elastic oil/water separation sponges by surface embedding.