Functional antimicrobial and anticorrosive polyurethane composite coatings from algae oil and silver doped egg shell hydroxyapatite for sustainable development

Petroleum products need to be replaced by renewable materials because of their ecological impact due to their non-degradable nature and tendency to shortages and price fluctuation. The present investigation reports the preparation of polyesteramide polyol (PEA-RIC) from renewable sources like algae oil and ricinoleic acid from castor oil. It was characterized by H-1 NMR and FT-IR spectroscopic techniques, while molecular weight was determined by size exclusion chromatography. Silver doped hydroxyapatite nanoparticles (Ag-HAP NPs) prepared using waste chicken egg-shells were incorporated uniformly in PEA-RIC and their morphology was studied by scanning electron microscopy. Polyol containing Ag-HAP NPs was cross linked using diisocyanate to obtain polyurethane (PU) nanocomposite coatings. Their anticorrosion performance was studied by potentiodynamic polarization (PDP) method while antibacterial activity was measured against Gram-negative (E. coli) and positive (S. aureus) bacteria. These nanocomposite coatings on metallic substrate inhibited both bacteria when checked by turbidimetric method and interestingly exhibited good resistance to bacterial adhesion and bio-film formation as evidenced by SEM analysis. These coatings showed improved hydrophobicity, adhesion, anticorrosive properties and chemical resistance as compared to PU without nanoparticles.. Thermal stability and Tg were found to improve with increasing concentration of Ag-HAP NPs when checked by TGA and DSC. Such coating originating from renewable materials exhibits high applicability in curbing the losses due to corrosion and assists sustainable development.