▎ 摘　　要

The exfoliation of graphene sheets has been achieved by using commercial graphite in the presence of spherical polymer nanoparticles based on poly(ethylene glycol). The polymer nanoparticles with an average diameter of similar to 20 nm were prepared by two different methods including the ball milling technique and a magnetic stirring process. These nanoparticles in conjunction with an ultrasonication procedure yielded graphene sheets of about three layers or less. The polymer nanoparticles played a crucial role in the preparation of the graphene sheets through a wrapping process. The number of graphene layers can be tuned by varying the preparation method of the polymer nanoparticles. (C) 2015 Elsevier B.V. All rights reserved.