| Summary: | A variety of polymeric surfaces, such as anti-corrosion coatings and polymer-modified asphalts, are
prone to blistering when exposed to moisture and air. As water and oxygen diffuse through the material,
dissolved species are produced, which generate osmotic pressure that deforms and debonds the
coating. These mechanisms are experimentally well-supported; however, comprehensive macroscopic
models capable of predicting the formation osmotic blisters, without extensive data-fitting, is scant.
Here, we develop a general mathematical theory of blistering and apply it to the failure of anti-corrosion
coatings on carbon steel. The model is able to predict the irreversible, nonlinear blister growth
dynamics, which eventually reaches a stable state, ruptures, or undergoes runaway delamination,
depending on the mechanical and adhesion properties of the coating. For runaway delamination, the
theory predicts a critical delamination length, beyond which unstable corrosion-driven growth occurs.
The model is able to fit multiple sets of blister growth data with no fitting parameters. Corrosion
experiments are also performed to observe undercoat rusting on carbon steel, which yielded trends
comparable with model predictions. The theory is used to define three dimensionless numbers which
can be used for engineering design of elastic coatings capable of resisting visible deformation, rupture,
and delamination.
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