NMR diffusometry and FTIR in the study of the interaction between antifouling agent and binder in marine paints

The interaction between an antifouling agent and binder in a model marine paint system has been thoroughly studied by NMR and FTIR techniques. NMR diffusometry was used to quantify the strength of binder-antifouling agent interaction and FTIR spectroscopy to study the mechanism of binding. Medetomidine was the antifouling agent and a long-chain alkyd resin was chosen as a binder. The diffusion coefficient of medetomidine indicates a strong interaction with alkyd in xylene. The amount of adsorbed antifouling agent has a threshold value, which is determined by the number of available active sites on the binder. As shown by FTIR such sites are predominantly carboxyl groups, although interaction with other sites is also possible.