Rheology-Guided Thermo-Mechanical Optimization of Gelatin/Oxidized Alginate Hydrogels

Abstract

Interpreting the rheological response of thermo-responsive hydrogels is challenging because heating alters both network elasticity and viscoelastic relaxation. Here, we establish a rheology-guided methodology to quantify these effects using a gelatin (Gel)/oxidized sodium alginate (OSA)/phenylboronic acid hydrogel. Two complementary normalized descriptors were introduced: the plateau-modulus loss ratio, quantifying retention of the elastically effective network during heating, and the normalized complex-viscosity ratio, capturing temperature-induced changes in viscoelastic response after accounting for solvent viscosity. Gelatin concentration governed network rigidity and deformability, while the Gel/OSA ratio controlled the balance between thermally labile physical junctions and Gel−OSA interactions. Within the investigated formulation space, a 2:1 Gel/OSA ratio provided the most favorable thermo-mechanical response, combining minimal elastic-network loss with a nearly frequency-independent normalized viscosity response. Self-healing, reprocessability, adhesion, and swelling tests further demonstrated multifunctional performance. These descriptors provide a quantitative framework for comparing thermo-responsive polymer networks and guiding formulation selection.