The mechanical exfoliation method was first described in 2008. It was in response to the need for a scalable production method for graphene. Mechanical exfoliation is a top-down approach that requires mechanical energy in order to exfoliate graphite.
Most commonly, techniques like sonication or high-shear-mixing are utilized. However, the efficiency of mechanical exfoliation is difficult to control. Consequently, this method usually leads to graphene flakes of widely varied size and thickness.
Graphene is a hydrophobic material, which is why additives or surfactants are required in order to obtain stable dispersions in polar solvents. Furthermore, many of the surfactants or organic solvents used can be toxic or otherwise harmful.
Although this production method is simple enough, the quality and purity of the exfoliated graphene may not be sufficient for specific applications.