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

Abstract

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, 1 H NMR, and 13 C 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.

Poly(acrylic acid)-b-Poly(vinylamine) Copolymer: Decoration with Silver Nanoparticles, Antibacterial Properties, Quorum Sensing Activity, and Cytotoxicity on Breast Cancer and Fibroblast Cell Lines

“…The characteristic chemical shifts of PAA were observed at 1.5−1.8 ppm for methylene protons (a) and 2.25 for methyne proton (b), 35 as shown in Figure 3a. In Figure 3b, additional peaks, such as formamide proton resonance at 7.90−8.20 ppm, broad overlapping methine proton and NH group resonance shifts of PNVF at 3.41 ppm, and methylene proton shift at 1.74, 40 were observed, which attest to the successful chain extension of PAA by the PNVF block. The shifts between 7.15 and 7.46 are due to aromatic protons in the structure of the EPEX RAFT agent.…”

“…42 The shift at δ = 8.40 ppm is due to the proton of residual sodium formate, the main side product formed during the hydrolysis of PNVF, while the shift observed at δ = 8.62 ppm is attributed to the residual N-vinyl formamide −R(C� O)H proton. 40 Comparing Figure 3b−d, it is seen that the relative peak intensity of formamide protons detected at around δ 7.90−8.20 ppm increases with the decrease in the amount of PAA@EPEX macro-CTA and hence increase in the molecular weight of PNVF blocks. The weight percent values of the PAA and PNVF blocks can be determined from the relative peak intensities of the methyne proton of PAA at around δ 2.24 ppm (peak b in Figure 3) and the formamide proton of PNVF detected at around δ 7.90−8.20 ppm (peak f in Figure 3) using eq S3 in the Supporting Information.…”

“…After copolymerization, additional peaks in δ 30−50 ppm region due to the methylene and methyne carbon shifts of PNVF, along with distinguishable multiplets between δ 160−164 ppm due to the formamide carbon of PNVF were detected. 40 The relative peak intensities of the formamide carbon increased with an increase in PNVF block length, Supporting Information from SEC, elemental analysis, and 1 H NMR spectroscopy. However, the 13 C NMR spectra were not used to calculate the percentages of the copolymer blocks, as the relatively low carbon peak intensities in the spectra may be affected by the background noise.…”

Poly(vinyl amine) microparticles derived from N-Vinylformamide and their versatile use

“…A detailed study covering the tunable fluorescent properties of prepared PVAm chains from acidic and basic hydrolysis of PNVF chains was reported by our group [37]. Therefore, the excitation and emission spectra of linear PVAm, PVAm-1, and PVAm-2 particles prepared in this work were analyzed accordingly and given in Fig.…”

“…The prepared PNVF polymers were hydrolyzed in basic conditions as described in the literature [24]. The structural characterization of PNVF and hydrolyzed forms, PVAm was performed by means of 1 H and 13 C NMR spectroscopies in details and reported in our previous study [37]. The degree of hydrolysis was also determined from 1 H NMR spectrum as 98.4% suggesting that most of the NVF groups were converted into VAm moieties [37].…”