Tuning the architectural flexibility and dynamic swelling boundaries of pectin-chitosan hydrogels using choline chloride-based deep eutectic solvents

In modified biopolymers, balancing high swelling with tensile compliance remains a major challenge due to water-induced structural collapse. The study aims to systematically tuning the spatial configuration of hydrogen bond donors, HBD (ethylene glycol, glycerol, and acetic acid) in DES to modulate network properties of pectin-chitosan hydrogels (E20, G20 and A20) and their environmental responsiveness, ensuring structural integrity while permitting swelling. The network exhibiting pH and temperature-responsive swelling across pH 3–11 and temperature 30–60 °C, as well as an ionic swelling capacity that varied with valence (Na + > Ca 2+ > Fe 3+ ). By acting as a molecular wedge that competitively disrupts rigid native ionic crosslinks, the ethylene glycol-based DES (E20) reduced the gel fraction to the lowest; 13.33 ± 1.71%, creating an open skeletal framework that achieved a superior water absorption capacity of 16.02 ± 0.15 g/g at pH 7 due to the minimal size and little steric hindrance of ethylene glycol-based DES. Architectural flexibility was proven through both tensile compliance (Young's modulus of 0.26–1.44 MPa) and static compression load tolerance up to 49.05 kPa (4.91–49.05 kPa) stress range with a minimal fracture. In addition, the cyclic endurance was demonstrated through five consecutive hydration-dehydration cycles. This work establishes a physical-chemistry foundation for predictive molecular design framework that successfully decouples architectural flexibility and compressive load tolerance from swelling-induced network failure. Through this work, a smart, multi-stimuli-responsive, flexible, and high-swelling biopolymer matrix could be tailored for demanding real-world applications such as smart agriculture and soft robotics.