Critical Peeling of Tethered Nanoribbons

TL;DR

This paper investigates the peeling behavior of tethered graphene nanoribbons at the nanoscale, revealing unique steady peeling regimes and novel scaling laws through analytical modeling, simulations, and atomistic MD studies.

Contribution

It introduces a new nanoscale peeling setup with a tethered tail, deriving novel scaling exponents and validating them with detailed simulations and atomistic models.

Findings

Discovery of a steady peeling regime with constant force at the nanoscale.

Identification of new power-law scaling exponents governing peeling dynamics.

Validation of analytical predictions through molecular dynamics simulations.

Abstract

The peeling of an immobile adsorbed membrane is a well known problem in engineering and macroscopic tribology. In the classic setup, picking up at one extreme and pulling off results in a peeling force that is a decreasing function of the pickup angle. As one end is lifted, the detachment front retracts to meet the immobile tail. At the nanoscale, interesting situations arise with the peeling of graphene nanoribbons (GNRs) on gold, as realized, e.g., by atomic force microscopy. The nanosized system shows a constant-force steady peeling regime, where the tip lifting h produces no retraction of the ribbon detachment point, and just an advancement h of the free tail end. This is opposite to the classic case, where the detachment point retracts and the tail end stands still. Here we characterise, by analytical modeling and numerical simulations, a third, experimentally relevant, setup where the nanoribbon, albeit structurally lubric, does not have a freely moving tail end, which is instead elastically tethered. Surprisingly, novel nontrivial scaling exponents appear that regulate the peeling evolution. As the detachment front retracts and the tethered tail is stretched, power laws of h characterize the shrinking of the adhered length the growth of peeling force and the peeling angle. These exponents precede the final total detachment as a critical point, where the entire ribbon eventually hangs suspended between the tip and tethering spring. These analytical predictions are confirmed by realistic MD simulations, retaining the full atomistic description, also confirming their survival at finite experimental temperatures.