Scaling of the critical free length for progressive unfolding of self- bonded graphene
K Kwan and SW Cranford, APPLIED PHYSICS LETTERS, 104, 203101 (2014).
Like filled pasta, rolled or folded graphene can form a large nanocapsule surrounding a hollow interior. Use as a molecular carrier, however, requires understanding of the opening of such vessels. Here, we investigate a monolayer sheet of graphene as a theoretical trial platform for such a nanocapsule. The graphene is bonded to itself via aligned disulfide (S-S) bonds. Through theoretical analysis and atomistic modeling, we probe the critical nonbonded length (free length, L-crit) that induces fracture-like progressive unfolding as a function of folding radius (R-i). We show a clear linear scaling relationship between the length and radius, which can be used to determine the necessary bond density to predict mechanical opening/closing. However, stochastic dissipated energy limits any exact elastic formulation, and the required energy far exceeds the dissociation energy of the S-S bond. We account for the necessary dissipated kinetic energy through a simple scaling factor (X), which agrees well with computational results. (C) 2014 AIP Publishing LLC.
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