Elasticity of polyelectrolyte multilayer microcapsules

TL;DR

This paper introduces a new AFM-based method to measure the elastic properties of polyelectrolyte multilayer microcapsules, revealing their elastic behavior and estimating their Young's modulus.

Contribution

The study develops a novel experimental approach combining AFM measurements with elastic membrane theory to determine microcapsule elasticity.

Findings

Capsules exhibit elastic deformation at low loads.

Estimated Young's modulus ranges from 1 to 100 MPa.

Values are comparable to elastomers.

Abstract

We present a novel approach to probe elastic properties of polyelectrolyte multilayer microcapsules. The method is based on measurements of the capsule load-deformation curves with the atomic force microscope. The experiment suggests that at low applied load deformations of the capsule shell are elastic. Using elastic theory of membranes we relate force, deformation, elastic moduli, and characteristic sizes of the capsule. Fitting to the prediction of the model yields the lower limit for Young's modulus of the polyelectrolyte multilayers of the order of 1-100 MPa, depending on the template and solvent used for its dissolution. These values correspond to Young's modulus of an elastomer.