Migration of fluorinated alkyd and fluorinated tung oil additives for partially self-stratifying coatings

A high solids alkyd coating was developed with surface active polymers to improve performance at the surface, while maintaining adhesion at the substrate. A fluorinated long oil alkyd (FLOA) was prepared through a partial polyol substitution of 2,2,3,3,4,4,5,5-octafluoro-1,6- hexanediol for glycerol with phthalic anhydride and linseed oil in a long oil alkyd (LOA). A previously synthesized fluorinated tung oil (FTO) reactive diluent was also synthesized via a Diels- Alder reaction with 2,2,2-trifluoroethyl methacrylate. The alkyd and reactive diluent were characterized with 1H-NMR and MALDI-TOF mass spectroscopy. The FLOA was used as an additive up to 40 wt.% of the total alkyd, in increments of 10 wt.%. The FTO was used as an additive up to 10 wt.% of the total alkyd, in increments of 2.5 wt.%. The film formation was examined using scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDX) to show phase separation and domains of the low surface energy additive. Analysis of a cross-section of the coating showed an increase in fluorine concentration of 40% at the surface, compared to substrate, which preserves adhesion. A variety of coatings tests were performed to evaluate hardness, adhesion, mechanical strength and flexibility of the coating. The contact angle of FLOA/FTO coatings shifted from hydrophilic to hydrophobic surface energy. An increase in corrosion protection for FLOA/FTO coatings was evaluated using electrochemical impedance spectroscopy (EIS).