Mapping water uptake in an epoxy-phenolic coating

• Water sorption into an epoxy-phenolic coating is correlated to cure time and free volume.
• AFM-IR is used to map local cure degree at the nanoscale.
• Local water sorption into the coating is monitored using AFM-IR.

Water sorption in epoxy networks is associated with deleterious physical effects such as swelling, hydrolysis, lowering of the Tg, cracking and crazing. Nonetheless, water uptake in epoxy coatings is poorly understood in relation to macromolecular structure. In this contribution, we study the effect of cure time (closely related to cross-linking density and free volume) on water uptake for a model epoxy-phenolic coating. Localised water uptake is then mapped with nanoscale lateral resolution using AFM-IR, and correlated to cross-linking density.

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