Development of alginate/starch-based hydrogels crosslinked with different ions: Hydrophilic, kinetic and spectroscopic properties

Hydrogels are polymeric materials that have been applied in the controlled release system. The formation of the three-dimensional network may extend the release process. The objective of this study was to optimize the concentrations of sodium alginate and starch polysaccharides and to evaluate the effect of different concentrations and crosslinking agents on hydrophilic, kinetic and spectroscopic properties. The hydrogels were prepared by immersing of polymeric solutions in recipients contained the crosslinker solution (MnCl2, ZnCl2 or CaCl2) in different concentration at 25 °C. Analysis of swelling degree revealed that hydrogels crosslinked with Mn2+ presented a larger equilibrium uptake in relation to Zn2+ and Ca2+. Kinetic studies showed that with increasing crosslinking density, there was an increase in the diffusion constant (k) values and that almost all of the hydrogels absorbed water preferentially by the Fickian diffusion mechanism. Fourier transform infrared spectroscopy (FTIR) analysis detected the functional groups referent the alginate and starch, and their interaction with the ions (Mn2+, Zn2+, Ca2+).