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. 2022 Jan 19;15(3):748.
doi: 10.3390/ma15030748.

Alginate Hydrogels with Aloe vera: The Effects of Reaction Temperature on Morphology and Thermal Properties

Katarzyna Bialik-Wąs  1 , Konstantinos N Raftopoulos  2 , Krzysztof Pielichowski  2
Affiliations

Alginate Hydrogels with Aloe vera: The Effects of Reaction Temperature on Morphology and Thermal Properties

Katarzyna Bialik-Wąs et al. Materials (Basel). .

Abstract

In this study, we investigated the impact of reaction temperature on the physicochemical, structural, morphological, and thermal properties of sodium alginate/poly (vinyl alcohol)-based hydrogels, both in the pure form and with the addition of 20% (v/v) Aloe vera solution. The materials were prepared by chemical crosslinking at temperatures in the range of 65-75 °C. Poly (ethylene glycol) diacrylate was used as a crosslinking agent. The extent to which the crosslinking reaction proceeded was studied as a function of the reaction temperature, along with the thermal properties and morphology of the final materials. A measurement of gel fraction, in agreement with differential scanning calorimetry and Fourier transform infrared spectroscopy, showed that a higher temperature of reaction promoted the crosslinking reaction. On the basis of the aforementioned techniques, as well as by energy dispersive X-ray analysis under an electron microscope, it was also shown that the bioadditive Aloe vera promoted the crosslinking reaction.

Keywords: Aloe vera; DSC analysis; hydrogels; sodium alginate/poly (vinyl alcohol) matrix.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
The potential interactions between SA, PVA, Aloe vera, and PEGDA.
Figure 1
Figure 1
The gel fraction of obtained hydrogel materials.
Figure 2
Figure 2
Swelling ratio (%) in (A,C) distilled water and (B,D) PBS for SA/PVA hydrogels: (A,B) without and (C,D) with Aloe vera. Note that the x-axis is not linear.
Figure 3
Figure 3
FTIR spectra of hydrogels before and after modification with Aloe vera, obtained at temperatures of (A) 65 °C, (B) 70 °C, and (C) 75 °C.
Figure 4
Figure 4
Heating DSC curves of the substrates. The curves have been translated for clarity.
Figure 5
Figure 5
Heating thermograms of the hydrogels: (A) first heating; (B) second heating. Labels indicate the reaction temperature.
Figure 6
Figure 6
Glass transition temperature as a function of reaction temperature.
Figure 7
Figure 7
SEM micrographs presenting the morphology of obtained hydrogels before immersion in PBS solution.
Figure 8
Figure 8
SEM-EDS analysis of hydrogels obtained using a temperature of 75 °C, before and after modification with Aloe vera.
Figure 9
Figure 9
SEM micrographs presenting the morphology of hydrogels obtained using a temperature of 75 °C; samples were analyzed after immersion in PBS solution for 24 h.
Figure 10
Figure 10
SEM micrographs show the cross-section of obtained hydrogels.
See this image and copyright information in PMC

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