The deformation of wrinkled graphene

TL;DR

This study investigates how wrinkled CVD graphene deforms under strain using Raman spectroscopy, revealing unique deformation behavior due to its microstructure of flat islands separated by wrinkles, modeled with shear lag analysis.

Contribution

It introduces a model for the deformation of wrinkled CVD graphene considering its microstructure, explaining Raman spectral changes under strain.

Findings

Raman 2D band shift rate is less than 25% of exfoliated graphene.

Band broadening rate is about 75% of exfoliated graphene.

Model predictions align well with experimental Raman data.

Abstract

The deformation of monolayer graphene, produced by chemical vapor deposition (CVD), on a polyester film substrate has been investigated through the use of Raman spectroscopy. It has been found that the microstructure of the CVD graphene consists of a hexagonal array of islands of flat monolayer graphene separated by wrinkled material. During deformation, it was found that the rate of shift of the Raman 2D band wavenumber per unit strain was less than 25% of that of flat flakes of mechanically-exfoliated graphene, whereas the rate of band broadening per unit strain was about 75% of that of the exfoliated material. This unusual deformation behavior has been modeled in terms of mechanically-isolated graphene islands separated by the graphene wrinkles, with the strain distribution in each graphene island determined using shear lag analysis. The effect of the size and position of the Raman laser beam spot has also been incorporated in the model. The predictions fit well with the behavior observed experimentally for the Raman band shifts and broadening of the wrinkled CVD graphene. The effect of wrinkles upon the efficiency of graphene to reinforce nanocomposites is also discussed.