Development of miniaturized peel experiments to quantify interfacial adhesion between 2D monolayers and viscoelastic polymers

ABSTRACT

In this work, a miniaturized peel-testing setup capable of performing peel tests for viscoelastic polymer strips attached to rigid substrate at different peel rates (20 nm/s–20 µm/s) and at constant peel angles (45°–135°) was developed. A mathematical framework accounting for competition between the delamination from rigid substrate as well as bending and extension of the peel arm during the peel test was employed for modeling the viscoelastic response of the soft polymeric strips attached to a rigid substrate. The efficacy of the novel miniaturized peel-testing setup was evaluated for linear elastic and viscoelastic peel arms attached to rigid substrates. The adhesion measurements for the linear elastic peel arms were found to be insensitive to peel angles and the values were in great agreement with standardized macroscale adhesion measurements for the same interface. The peel tests revealed that the interfacial adhesion measurements for the viscoelastic PDMS peel arms were highly sensitive to the nominal peel rates. An elaborate specimen fabrication process was developed to evaluate the interfacial adhesion between large area 2D materials and soft polymer substrates. A series of peel-testing experiments were performed to ensure that the developed fabrication process does not adverse effects on the interfacial adhesion measurements. The peel-testing methodology was then employed to quantify the interfacial adhesion between graphene monolayers and PDMS substrates. Due to the weak van der Waals interactions associated with the graphene/PDMS interface, the interfacial adhesion measurements for this interface was significantly lower than the adhesion values for a PDMS/PDMS interface.

KEYWORDS:

• Interfaces
• viscoelasticity
• peel-test
• graphene

Acknowledgments

The financial support for this work granted by the Worcester Polytechnic Institute faculty startup fund is greatly acknowledged. The authors would like to thank Hrachya Kocharyan and Prajwal Bharadwaj for their help with specimen fabrication and data analysis.