Benzoxazine monomers grafted poly(acrylic acid) as novel organic additives with fluorescence and antibacterial properties

Novel additives with dual fluorescence and antibacterial properties derived from benzoxazine monomers and poly(acrylic acid) (PAA) were prepared. Three benzoxazine monomers containing a hydroxyl group (BZXs) synthesized via the Mannich reaction were used as organic fluorophores and subsequently reacted with PAA to obtain poly(acrylic acid)-grafted benzoxazines (PAA-g-BZXs) via esterification. The results from Fourier transform infrared (FTIR) spectroscopy and H-1 nuclear magnetic resonance (NMR) showed that the BZXs were grafted onto the pendent groups of PAA only 25%. From UV-Vis, the maximum absorption wavelengths of PAA-g-BZXs were shown the same position of BZXs. By fluorescence spectroscopy, the excitation, emission, and fluorescence quantum yield of BZXs were found to be 375-480 nm, 550-585 nm, and 0.60, respectively. Meanwhile, PAA-gBZXs showed the same excitation and emission wavelength positions around 360-485 nm and 500-585 nm, respectively. PAA-g-BZXs exhibited green emission light under a UV lamp due to the benzoxazine pendent groups. However, the fluorescence quantum yield of PAA-g-BZXs was decreased to be 0.40 BZXs due to only 25% of BZXs grafted on the pendent groups of PAA. Moreover, PAA-g-BZXs showed antibacterial activity against S. aureus and E. coli up to 100%. Only 1% by weight PAA-g-BZXs was an appropriate amount for the poly(lactic acid) (PLA) matrix to fabricate golden PLA/PAA-g-BZXs composite wires without adding any pigments since the obtained composite wires still showed a high optical performance by changing the color from gold under visible light to blue-green under UV irradiation.

Automated summary

Novel additives with dual fluorescence and antibacterial properties, derived from benzoxazine monomers and poly(acrylic acid) (PAA), were prepared. The obtained PAA-g-BZXs exhibited good fluorescence and antibacterial activity, and showed high optical performance when used as additives in composite wires.