Bifunctional polybenzoxazines have been developed using sustainable bio-phenol curcumin, paraformaldehyde with varying nature of monofunctional amines through Mannich condensation. The molecular structure of synthesized benzoxazines were confirmed by ATR-FTIR, 1HNMR and 13CNMR and high-resolution mass spectroscopic (HRMS) analyses. DSC thermograms were used to ascertain the curing behaviour of curcumin-based monomers. Thermal curing of Cu-api occurs at 192 °C and that of Cu-aa undergoes dual curing at 177 °C and 209 °C due to its inherent molecular structure. The thermal stability of synthesized polybenzoxazines was studied using TGA, Cu-a exhibits higher char yield of 63% due to higher aromatic content than that of other polybenzoxazines. The occurrence of dimerization (2π+2π cycloaddition) of curcumin based benzoxazines proceeds through conjugation present in the main chain of curcumin when exposed to UV irradiation, and was monitored through UV–visible spectroscopy. All the synthesized benzoxazine monomers were excited within the wavelength of UV range with occurrence of photoluminescence behaviour in visible region ranges between 448 nm and 530 nm. The value of band gap calculated for the curcumin-based monomers ranged from 3.55 to 3.77 eV. The explicit character of curcumin based benzoxazines can be exploited in the field of optical applications. The hydrophobic behaviour of polybenzoxazines was also studied and the highest water interface angle value of 146° was observed for poly(Cu-tfma) due to the presence of fluorine groups. Furthermore, the Cu-tfma coated cotton fabric was tested for its durability and the results indicated that these materials coated cotton fabrics are better suitable for sustainable high performance hydrophobic applications. The anti-corrosion studies indicated that the poly(Cu-api) coated on mild steel exhibits greater resistance towards corrosion amongst the other polybenzoxazines which can be potentially employed as coating in marine environments.