Tailoring hybrid topologies via conformation-driven matrix dynamics: Comparative evaluation of hyaluronic acid, gelatin, inulin, β-cyclodextrin, and corn starch incorporation.

This study investigates how the architecture of incorporated biomacromolecules regulates the structure and responsive behavior of hybrid polymer networks. An anionic poly(acrylamide-co-itaconic acid) (PAIM) network containing ZnO nanoparticles and polyphenol-rich Myristica fragrans Houtt. (mace) extract was designed as pH-responsive multifunctional host matrix, providing secondary physical interactions and multifunctional properties, while hyaluronic acid, gelatin, corn starch, inulin, and β-cyclodextrin were incorporated to systematically vary the molecular architecture of the guest component. Addition of biomacromolecules significantly modulated overall swelling, deswelling, and mechanical responses depending on the structure of incorporated guest components by altering the microstructure and cross-linking density. Equilibrium swelling decreased in the order blank ZnO/PAIM > Corn starch > Inulin > Hyaluronic acid > Gelatin > β-cyclodextrin. Corn starch provided the highest swelling among the hybrid formulations, whereas the rigid cyclic structure of β-cyclodextrin limited volume loss to 29.8% under high-salinity conditions. Structural incorporation of large and dense biomacromolecules into PAIM network significantly constrained the microstructure, while hyaluronic acid, gelatin, and corn starch modified formulations demonstrated structural self-reinforcement upon hydration. At pH 11.2, corn starch-integrated hybrid showed a 4.7-fold increase in swelling, whereas β-cyclodextrin-containing matrix exhibited only a 1.3-fold change. The study hypothesized that incorporating biomacromolecules with different molecular architectures would modulate dynamic swelling behavior by restricting chain mobility and influencing polymer-chain relaxation during water uptake. Consistent with this hypothesis, biomacromolecule incorporation altered the overall swelling kinetics and the relative contributions of water diffusion and network relaxation within ZnO/PAIM matrix. All formulations exhibited pseudo-Fickian swelling behavior, with swelling exponent n values ranging from 0.1562 for blank network to 0.3628 for corn starch-containing hybrid, suggests a greater contribution of polymer-chain relaxation to swelling response. The relatively small variation in n values was interpreted as a change in the relative contribution of diffusion and network relaxation rather than as evidence of different swelling mechanisms. Schott's pseudo-second-order model provided a satisfactory empirical description of the overall swelling process toward equilibrium. This systematic structural screening provides a direct benefit for hybrid design, demonstrating that the network relaxation, mechanical response and fluid kinetics of smart hybrid networks can be tailored by varying the architectural geometry of the guest biomacromolecule.