Tunable fluorescent and antimicrobial properties of poly(vinyl amine) affected by the acidic or basic hydrolysis of poly(N-vinylformamide)

Synthesis of poly(N-vinylformamide) (PNVF) and its subsequent hydrolysis to convert it to poly(vinyl amine) (PVAm) were performed. Kinetics of acidic and basic hydrolysis of poly(N-vinylformamide) (PNVF), and products of hydrolysis were investigated by using Fourier transform infrared, size exclusion chromatography, H-1 NMR, and C-13 NMR spectroscopies, and thermogravimetric analysis. It was observed that amide groups did not completely transform into amine groups by acidic hydrolysis of PNVF while the conversion of amides into amine groups via basic hydrolysis of PNVF was complete in 12 h, as confirmed by spectroscopic measurements. Results of extensive characterization revealed significant structural and conformational differences between acidic and basic hydrolysis products. Fluorescence spectroscopy was used for the first time to follow the conversion of amide groups into amine groups. The fluorescence intensity of PVAm obtained from basic hydrolysis of PVNF showed significant increase with amide/amine conversion. Finally, PVAm obtained from acidic hydrolysis of PNVF demonstrated potent antimicrobial activity, 10-20 times more, against common pathogens for example, C. albicans as fungal strain and E. coli, S. aureus, B. subtilis, and P. aeruginosa as bacterial strains as compared to PVAm obtained from basic hydrolysis.

Automated summary

The synthesis of poly(N-vinylformamide) (PNVF) and its subsequent hydrolysis to poly(vinyl amine) (PVAm) were investigated in this study. The kinetics and products of acidic and basic hydrolysis of PNVF were examined using various spectroscopic techniques, revealing structural differences between the two hydrolysis methods. Fluorescence spectroscopy was used for the first time to track the conversion of amide groups to amine groups, showing a significant increase in fluorescence intensity in PVAm from basic hydrolysis. PVAm from acidic hydrolysis demonstrated potent antimicrobial activity against common pathogens compared to PVAm from basic hydrolysis.