Buckling and snapping of a thin polymeric membrane exposed to a solvent drop

Micro Nano Bio - Fluidics Unit, Fluid Systems Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India

Received: 25 July 2020
Accepted: 23 October 2020

Abstract

We report the behavior of a thin and flat rectangular polymeric membrane, fixed at both ends, in contact with a solvent droplet. Depending on the solvent type and volume, and membrane thickness, three different regimes —no buckling, buckling, and snapping— are observed. Our study reveals that the behavior depends on the solubility parameter of the solvent and the ratio of the sum of swelling-induced force and capillary force to the elastic restoring force, i.e., the force ratio. We attempt to explain the phenomenon using the poroelastic and elastic recoil timescales. Using correlations from simple scaling, our model can estimate the maximum force ratio in terms of known quantities and predict the operating regime and maximum deflection. We expect our study will find significance in the design and analysis of systems involving flexible microbeams.