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Study of the Effect of Grafting Method on Surface Polarity of Tempo-Oxidized Nanocellulose Using Polycaprolactone as the Modifying Compound: Esterification versus Click-Chemistry

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ABSTRACT

Esterification and click-chemistry were evaluated as surface modification treatments for TEMPO-oxidized nanocelluloses (TONC) using Polycaprolactone-diol (PCL) as modifying compound in order to improve the dispersion of nanofibers in organic media. These two grafting strategies were analyzed and compared. The first consists of grafting directly the PCL onto TONC, and was carried out by esterification between hydroxyl groups of PCL and carboxyl groups of TONC. The second strategy known as click-chemistry is based on the 1,3-dipolar cycloaddition reaction between azides and alkyne terminated moieties to form the triazole ring between PCL and TONC. The grafted samples were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Thermogravimetry analysis (TGA). Further, the effects of the two treatments on the surface hydrophobization of TONC were investigated by contact angle measurements. The results show that both methods confirm the success of such a modification and the click reaction was significantly more effective than esterification.

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FTIR spectra of PCL (a) and azido-polycaprolactone (PCL-N3) (b).
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nanomaterials-03-00638-f003: FTIR spectra of PCL (a) and azido-polycaprolactone (PCL-N3) (b).

Mentions: Figure 3 shows the FTIR spectra of PCL and PCL-N3. The spectrum of PCL (spectrum a) shows a peak around 3500 cm−1 and a very sharp signal at 1750 cm−1, corresponding to hydroxyl and ester groups, respectively. When tosylated polycaprolactone reacted with NaN3, the FTIR spectrum of PCL-N3 (spectrum b) showed a considerable decrease in the intensity of the hydroxyl groups at 3500 cm−1 and the appearance of a new intense band at 2096 cm−1 typical of the azide groups, which confirms clearly that more and more azide molecules are covalently coupled to the surface of PCL chains.


Study of the Effect of Grafting Method on Surface Polarity of Tempo-Oxidized Nanocellulose Using Polycaprolactone as the Modifying Compound: Esterification versus Click-Chemistry
FTIR spectra of PCL (a) and azido-polycaprolactone (PCL-N3) (b).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5304593&req=5

nanomaterials-03-00638-f003: FTIR spectra of PCL (a) and azido-polycaprolactone (PCL-N3) (b).
Mentions: Figure 3 shows the FTIR spectra of PCL and PCL-N3. The spectrum of PCL (spectrum a) shows a peak around 3500 cm−1 and a very sharp signal at 1750 cm−1, corresponding to hydroxyl and ester groups, respectively. When tosylated polycaprolactone reacted with NaN3, the FTIR spectrum of PCL-N3 (spectrum b) showed a considerable decrease in the intensity of the hydroxyl groups at 3500 cm−1 and the appearance of a new intense band at 2096 cm−1 typical of the azide groups, which confirms clearly that more and more azide molecules are covalently coupled to the surface of PCL chains.

View Article: PubMed Central - PubMed

ABSTRACT

Esterification and click-chemistry were evaluated as surface modification treatments for TEMPO-oxidized nanocelluloses (TONC) using Polycaprolactone-diol (PCL) as modifying compound in order to improve the dispersion of nanofibers in organic media. These two grafting strategies were analyzed and compared. The first consists of grafting directly the PCL onto TONC, and was carried out by esterification between hydroxyl groups of PCL and carboxyl groups of TONC. The second strategy known as click-chemistry is based on the 1,3-dipolar cycloaddition reaction between azides and alkyne terminated moieties to form the triazole ring between PCL and TONC. The grafted samples were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Thermogravimetry analysis (TGA). Further, the effects of the two treatments on the surface hydrophobization of TONC were investigated by contact angle measurements. The results show that both methods confirm the success of such a modification and the click reaction was significantly more effective than esterification.

No MeSH data available.