Clean synthesis and characterization of green nanostructured polymeric thin films from endogenous Mg (II) ions coordinated methylolated-Cashew nutshell liquid

Abstract Efficient utilization of renewable feedstocks has been considered pivotal in sustainable development, controlling global warming, and as an alternative to petrochemical precursors. Here, we have presented a facile one-pot synthesis method for the fabrication of bacterial resistant, free-standing polymeric films and coatings by utilizing agro-waste based precursor material. The conversion of cashew nut shell liquid (CNSL) into a value-added product for this application was achieved through coordination of methylolated-CNSL and Mg (II) ions (Mg(II)CNSL). The resulting metal-organic framework (MOF) was then cured by following a greener approach with zero toxic/residue production through reacting Mg(II)CNSL with aliphatic amine [Mg(II)CNSL-FA]. The formulation mechanism of nanostructured Mg(II)CNSL-FA via the ring-opening reaction of benzoxazine, its polymerization with hydroxyl groups in CNSL, and coordination of Mg(II) ions were elucidated by FTIR, ATR, XRD, SEM/TEM, and DSC studies. The performance (flexibility, swelling behaviour, and water contact angle values), morphology, and thermal stability of Mg(II)CNSL-FA films were also compared (virgin ligand, CNSL-FA). The potential application of the film as an antibacterial material has been further tested against various bacterial strains ( E.coli, P. aeruginosa, S. aureus, and B. subtilis ). Overall, the research work is expected to broaden the utilization of CNSL, an agro-waste via cleaner production of flexible, free-standing, metal ions coordinated antibacterial film with possible application in surface coatings, adsorption, and water purification.