Mechanical and swelling properties of alginate-based hydrogel composites blending with PVA and PVP

Abstract

Alginate-based hydrogel composites were prepared by varying blending proportion of sodium alginate (Alg) with polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP), to optimize the mechanical properties and swelling behavior of hydrogel. The network structure of hydrogel was generated by ionic crosslinking process with using 2% calcium chloride (CaCl₂) as gelling agent. It was observed that higher Alg content resulted in faster gelation, greater swelling behavior in both deionized water and saline solution, due to the increased number of hydrophilic carboxyl groups. On the other hand, in terms of mechanical properties, the 2% alginate hydrogel exhibits optimal mechanical performance. Therefore, 2% alginate was selected as the suitable concentration for the preparation of polymer blend hydrogel composites. The study of polymer blending demonstrates that the abundance of hydroxyl groups in PVA enhances water uptake in hydrogel composites (Alg/PVA and Alg/PVA/PVP). However, these hydroxyl groups also promote hydrogen bonding, leading to increased rigidity of the hydrogel films. In contrast, Alg/PVP blending shows no significant influence on the swelling behavior of the hydrogels, although PVP improves elongation at break. As a result, the ternary Alg/PVA/PVP hydrogel composite exhibits synergistic effect, significantly enhancing optimal balance between mechanical strength and flexibility.