Antifreeze moisture-retaining coating based on ionic dextrin-hydroxyethylcellulose hydrogels: An initial insight into...

The development of antifreeze and moisture-retaining materials is important for cold-chain packaging, outdoor infrastructure, and agricultural protection. In this study, three Dextrin-hydroxyethyl cellulose (HEC) hydrogels with distinct crosslinking strategies were investigated: H1, a borate-acrylic acid covalently crosslinked network; H2, a poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS)-modified hydrogel with mixed ionic-electronic conduction; and H3, an aluminium chloride (AlCl₃)-coordinated ionically crosslinked network. These architectures enable the systematic evaluation of structure-water-ion interactions that influence antifreeze behavior. All hydrogels exhibit high swelling ratios (up to ∼2100%) and rapid hydration kinetics (up to 500% h^-1). Differential scanning calorimetry reveals a progressive increase in non-freezable water content from H1 to H3, with H3 showing the lowest melting enthalpy and an estimated non-freezable water fraction of ∼55-60%, indicating enhanced bound-water formation that suppresses ice nucleation and growth. H3 also retains ∼90% of its swelling capacity and ionic conductivity after 100 freeze-thaw cycles, outperforming H2 (75-82%) and H1 (<50%). Electrochemical impedance spectroscopy further demonstrates that Al³⁺-mediated ionic conduction in H3 yields the highest ionic conductivity (7.3 × 10^-3 S/cm) and stable transport pathways. Importantly, this work elucidates how polysaccharide network architecture regulates bound-water formation by systematically comparing covalent, mixed ionic-electronic, and ionically coordinated Dextrin-HEC hydrogels, establishing ion-mediated hydration as a key factor controlling non-freezable water content and antifreeze durability. These findings provide mechanistic guidance for developing sustainable carbohydrate-based antifreeze hydrogels for moisture-retaining and low-temperature applications.