Kashmiri Borah, Siddhartha Shankar Kashyap, Kavya Lekha Sunkara, Rakesh Rapolu, Sunil Misra, Aruna Palanisamy
ABSTRACT Non‐isocyanate polyurethanes (NIPUs) offer eco‐friendly, non‐toxic alternatives to conventional isocyanate‐based systems. Here, NIPU cationomers bearing quaternary ammonium functionalities were synthesized via a fully isocyanate‐ and solvent‐free process. Epoxidized soybean oil (ESBO) was converted to carbonated soybean oil (CSBO) by CO 2 insertion and subsequently formulated with ethylenediamine (EDA) and glycidyl trimethylammonium chloride (GTMAC) in varying proportions (0, 2.5, 5, and 10 wt.% relative to CSBO), forming a crosslinked epoxy‐urethane network containing covalently bound quaternary ammonium groups, designated as NIPU‐GTMAC. The resulting tack‐free, free standing films exhibited moderate thermal stability (~250°C) and a glass transition temperature in the range of 19°C–23°C. Swelling, gel content (> 95%), and DMA‐derived effective crosslink density confirmed the formation of robust crosslinked networks. GTMAC incorporation modified the thermomechanical and surface properties, with NIPU‐GTMAC‐5 exhibiting the highest water contact angle and the most balanced coating performance. SEM‐assisted bacterial adhesion studies demonstrated reduced bacterial attachment on GTMAC‐containing films, indicating contact‐active anti‐bioadhesion/antifouling behavior. Electrochemical and salt spray investigations revealed superior corrosion protection for NIPU‐GTMAC‐5, supported by excellent adhesion, flexibility, abrasion resistance, and barrier properties. These findings demonstrate the potential of soybean oil‐derived NIPU‐GTMAC coatings as sustainable multifunctional protective coatings.