Potassium-graphite intercalation compound (K-GIC), a kind of donor-acceptor complex of host graphite with potassium was allowed to react with unsaturated hydrocarbons such as stylene. Several tens of minutes after contact with the vapour of monomer, K-GIC was found to have expanded along the c-axis direction. Molecules of unsaturated hydrocarbons are considered to be introduced into the interlayer of K-GIC and polymerized progressively. This suggests that the stacked graphene layers are drawn apart. When polymer was dissolved with an appropriate solvent, a graphene sheet would be isolated. In such a case, graphene sheet will be rolled up to decrease the surface energy. In the scroll between the faced sides of the graphene sheet, van der Waals interaction is expected. The structure is quite different from that of carbon nanotubes prepared by the conventional arc-discharge or laser vaporization method.