Mechanically robust and antibacterial coatings constructed from cardanol-aliphatic amine based metal-coordinated nanostructured framework

The use of feedstocks from waste resources represents an exciting class of precursor to valorize. Primarily due to their low cost, non-competition with food and feed generation, and their contribution towards the waste disposal issue. In this regard, Cardanol (Col) emerged as an important precursor in the coating industry, obtained from the inedible shells of cashew nut, thus eliminating petroleum and other toxic chemicals. The present work presents a green route to engineer nanostructured polybenzoxazine (PBz) from bio-based precursor (Col) with remarkable characteristics. The coordination polymeric (CP) films were engineered using Col, formaldehyde, methenamine and different transition metal ions, i.e., Mn(II), Co(II), Ni(II), and Zn(II) to produce M(II)-mCol-AliBz for application in the field of antibacterial films/coatings. The thermal stability, physico-mechanical performance, and antibacterial activities against different bacterial strains were evaluated for the prepared films/coatings. The Co(II)-mCol-AliBz shows the highest thermal stability with IPDT value of 1165 °C, LOI (31.1), and functionality among other CPs with varied metal ions. The Co(II) and Ni(II) based mCol-AliBz films comparatively showed most efficient antibacterial performance against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The high surface hydrophobicity (90–112°), excellent thermal stability, and good anti-bacterial properties of the films/coatings make them a good surface protective materials.