Biobased furan-based epoxy/TiO2 nanocomposites for the preparation of coatings with improved chemical resistance

Biobased, solvent-free thermosetting coating systems are developed from epoxidized hydroxymethylfuran (BOMF) crosslinked with methyl nadic anhydride (MNA) filled with TiO2 nanoparticles. The effect of 1 to 5 wt% of TiO2 on the curing behavior of the resin and the overall performance of the resulting coatings is studied by means of rheological, thermal, mechanical, morphological, and chemical resistance tests. TiO2 particles shift the curing reaction to higher temperatures and reduce the reaction enthalpy, resulting in lower crosslinking degrees and glass transition temperatures. The resins are applied as tinplate coatings, exhibiting optimal adhesion to the metal substrate (5A according to ASTM D3359), and performing well in pencil hardness tests (9H and 7H in gouge and scratch hardness, respectively). Morphological characterization highlights homogeneous distribution of TiO2 nanoparticles even at the highest loading. Finally, the chemical resistance of the coatings to ethanol and acetic acid solutions used as simulants is significantly enhanced by the addition of TiO2, resulting in an efficient protection of the tinplate from corrosion. Overall, these results demonstrate that the proposed furan-based thermosets show potential for use as coatings.