Thermal behavior of polyvinyl alcohol–gellan gum–Al3+ composite hydrogels with improved network structure and mechanical property

In this work, the composite hydrogels of polyvinyl alcohol (PVA)–gellan gum (GG)–aluminum ion (Al3+) have been prepared by a repeated freezing and thawing method. By analyzing its structure, mechanical properties and thermal behavior, our result indicates that the ion of Al3+ plays a role of cross-link agent, and it reorganizes the network structure and enhances the mechanical properties for the composite hydrogels. Differential scanning calorimetry has been used to examine the thermal behavior. The melting enthalpy was obtained to evaluate the degree of crystallinity for PVA in hydrogel, which decreases with the increase in the content of GG. The decomposition temperature was obtained to evaluate the thermal stability. And the dehydration activation energy was obtained to evaluate the thermal behavior of water in hydrogel environment. Our result reveals that Al3+ ion enhances the molecular interactions between water and polymer chain, and improves the thermal stability of PVA–GG–Al3+ composite hydrogel. These results will benefit the development of hydrogel in bio-applications.