Partially acrylated linseed oil UV-cured coating containing a dihemiacetal ester for the corrosion protection of an aluminium alloy

Abstract The present work focused on the development of a partially bio-based polymer matrix for the corrosion protection of the 3003 aluminium alloy. A dihemiacetal ester (1,10-dibutoxyethyl sebacate (DBES)) was added to the formulation to afford, after an additional thermal treatment, further cross-linking and a repairing effect of the polymer matrix. First, an epoxidized linseed oil was partially acrylated and subsequently copolymerized with (3,4-dihydroxyphenetyl)-acrylamide and N,N-dimethyl acrylamide, with and without DBES under UV irradiation. Under thermal treatment, the DBES released dicarboxylic acid able to react with epoxy functions. The corrosion protection of the resulting coatings (with and without DBES and with and without the thermal treatment) was assessed by electrochemical impedance spectroscopy (EIS). The diagrams were obtained for various immersion times in a 0.5 M NaCl solution. The coatings had good barrier properties, which remained stable throughout the duration of the impedance measurements (two weeks). The addition of the DBES in the formulation, followed by the thermal treatment, resulted in an increase of the barrier properties, a decrease of water uptake and a healing of some small matrix defects. The improvement of the anticorrosion ability of the coating containing the DBES after the thermal treatment was attributed to an additional cross-linking. This work illustrates an original strategy for the development of self-healing bio-based coatings by using temporarily protected functions (here, dihemiacetal ester functions).