Synthesis and characterization of succinylated pectin hydrogels with enhanced swelling performances

A novel polymeric material was obtained through succinylation of pectin (S-Pec), resulting in greater stability, film-forming ability, transparency, swelling, and water retention capacity compared to native pectin (Pec). Spectroscopic techniques confirmed the success of the succinylation reaction performed on pectin, employing the reaction of galacturonic acid with succinic anhydride as a model reaction under similar experimental conditions. Moreover, fluorinated succinic anhydride was used to gain insight into the succinylation degree by X-ray Photoelectron Spectroscopy, and a different thermal behavior of S-Pec compared to Pec was confirmed through thermoanalytical characterization. Additionally, the effect of cross-linking either Pec or S-Pec in the presence of divalent cations (i.e., calcium or magnesium ions) on water retention capacity and stability was tested. A significant improvement in the ability to absorb and retain water or saline solution was found for magnesium-crosslinked succinylated pectin, while the in vitro hydrogel stability was higher for the calcium-crosslinked one. The obtained polymer represents a promising substrate for the development of natural-based superabsorbent polymers. • Succinilation of pectin was carried out for the first time in a straightforward procedure. • Model reaction was carried out employing D-galacturonic acid or tetrafluorosuccinic anhydride. • A complete chemical-physical characterization was carried out by FT-IR, XPS, NMR, DSC and TGA. • Polymer films of succinylated pectin, as such or ionically crosslinked, were produced. • Swelling performances, viscoelastic and tensile properties were evaluated on the obtained films.