▎ 摘　　要

Different morphologies of graphene can provide a great potential for applications of graphene-based nano-devices and functional nano-materials. Using molecular dynamic simulations, we show that by altering the temperature, one can induce unfolding of short (length less than similar to 50 nm) scrolled or folded graphene to a planar state. The mechanism of these phenomena is that temperature modifies the stability of these unclosed structures. We show in particular that morphology transformation of graphene is not explained by the change of the potential energy of the system, but rather it can be explained by a free energy analysis based on thermal dynamics. (C) 2014 AIP Publishing LLC.