Polyurethane Prepared from Neem Oil Polyesteramides for Self-Healing Anticorrosive Coatings

Polymeric researchers desire strongly to reduce dependency on fossil or petroleum feed stock by utilizing renewable source based polymeric resins in coating. The present research represents the attempt made to develop neem oil (a renewable source) two-pack self-healing anticorrosive polyurethane (PU) coatings cured at room temperature. The oil-based polyesteramide was prepared in two steps; viz., in the first step, oil fatty amide was synthesized, and in the second, it was directly converted to polyesteramide by condensing amide with phthalic anhydride. A spectral study of prepared resin was carried by FT-IR and NMR techniques. Polyesteramide further was utilized for preparation of self-healing PU coatings with incorporation of polyamidoamine based polyurea microcapsules containing natural self-healing agent. The obtained coatings were tested for thermal, physicochemical, and corrosion resistance tests. The coating properties, like gloss, impact resistance, adhesion, and flexibility, were also studied and found to be superior for anticorrosive self-healing industrial coatings.