Unlocking the potential of hydroxylated‐chalcone‐based photosensitive benzoxazines: synthesis, multifunctional properties and theoretical insights from density functional theory

Abstract This work pioneers the synthesis of a new class of benzoxazine monomers incorporating hydroxylated chalcone units (HAN‐HB) using 2′‐hydroxy‐1′‐acetonaphthone (HAN) and p ‐hydroxybenzaldehyde (HB) by following the Claisen–Schmidt condensation process. Three types of structurally varied bifunctional benzoxazines (Bz) were prepared using HAN‐HB and paraformaldehyde separately with tyramine (ty), 3‐amino‐1‐propanol (ap) and 2‐(2‐aminoethoxy)ethanol (aee) by adopting Mannich condensation. Both the HAN‐HB and benzoxazine molecular structures were confirmed by different spectroscopic analyses. DSC analysis reveal that HAN‐HB‐ap benzoxazine showed the lowest T p value of 214 °C. Poly(HAN‐HB‐ty) possesses the highest values of thermal decomposition temperature and percentage char yield. Further, all the polybenzoxazines exhibit self‐extinguishing and good heat‐resistant properties. In addition, the synthesised benzoxazines showed good anti‐microbial behavior. Photosensitive properties of the benzoxazines were studied using UV–visible spectroscopic analysis and the results indicated that the synthesised benzoxazines exhibited both photo‐isomerisation and photocrosslinking due to their inherent molecular rearrangement ability. An aggregation‐caused quenching characteristic was observed for the benzoxazines through a fluorescence study. From the water contact angle study, it was inferred that all the poly(HAN‐HB‐Bz) exhibited a water repellent nature and showed a higher water contact angle of 151°. The corrosion‐resistant behaviour of polybenzoxazines towards a mild steel surface was studied and the results obtained infer that these materials exhibit good protection efficiency. Density functional theory studies were performed for all the chalcone‐based benzoxazines. The incorporation of hydroxyl groups not only improves hydrogen bonding interactions, enhancing thermal stability, but also introduces photo‐reactivity. This dual functionality is not commonly reported in conventional benzoxazines. The results obtained from various studies suggest that the developed chalcone‐based benzoxazines can be suitably exploited for advanced photosensitive coating applications. © 2025 Society of Chemical Industry.