  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.
