Epoxidized and Cyclocarbonated Star-Shaped Macromolecules as Bio-Based Internal and External Crosslinkers for Superabsorbent Polymer Hydrogels

Regarding the sustainability point of view, this study is dedicated to the use of two bio-based star-shaped crosslinkers for superabsorbent hydrogel (SAP) applications as replacement of fossil-based counterparts. The epoxide crosslinker (E-st-G-SA) was synthesized from the reaction of a star-shaped macromonomer based-on glycerol and succinic acid with epichlorohydrin. The second crosslinker (C-st-G-SA) was prepared through the CO2 fixation reaction of E-st-G-SA. After characterization of crosslinkers by H-1 NMR and FTIR spectroscopies, E-st-G-SA was used as an internal crosslinker for SAP formulations. Next, the potential of E-st-G-SA and C-st-G-SA as surface crosslinkers for the abovementioned SAP was examined and C-st-G-SA presented a significant improvement of swelling under load up to - 38%, so it was selected as the preferred surface crosslinker for additional investigations. Moreover, rheological properties of the surface crosslinked SAPs demonstrated a higher swollen gel strength compared to that of intact SAP. The thermal stability of the intact and surface crosslinked samples was compared and the result showed an overall similar trend. Finally, the antibacterial activity of samples was evaluated and the results presented a satisfactory antibacterial property especially against S. aureus bacterium for the surface crosslinked sample but not for the intact one.