Synthesis of novel multi-hydroxyl N-halamine precursors based on barbituric acid and their applications in antibacterial poly(ethylene terephthalate) (PET) materials.

Two novel multi-hydroxyl N-halamine precursors were successfully synthesized in a green and facile way via Knoevenagel condensation reaction between barbituric acid and an aldehyde (citral or cinnamaldehyde), followed by a hydroxylation reaction with hydrogen peroxide. 1H-NMR and FT-IR spectral analyses confirmed their formation. Through the melt-blending process, the multi-hydroxyl derivatives of barbituric acid were introduced via transesterification into poly(ethylene terephthalate) (PET) at 265 °C in a rheometer. The crystallization behaviors of the modified PET samples were investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and polarized optical microscopy (POM) analyses. The results showed that the crystallization temperature and crystallization rate of PET were significantly improved upon the introduction of the precursor. Meanwhile, the relative crystallinity of the modified PET samples increased with an increase in the dosage of the N-halamine precursor. After the treatment with sodium hypochlorite solution, the PET surfaces modified with N-halamine derivatives would impart powerful antibacterial properties and achieve 100% killing of Staphylococcus aureus (ATCC 6538) and Escherichia coli (CMCC44103) cells within 30 min. Therefore, the multi-hydroxyl N-halamine precursors exhibit great potential as bifunctional additives (nucleating and antibacterial agents) in the manufacturing of functional PET materials.