Extremely Ultrahigh Stretchable Starch-Based Hydrogels with Continuous Hydrogen Bonding

Abstract

Natural polysaccharides-based hydrogels have drawn extensive attention yet have been plagued by less desirable stretchability due to their inherent nature. Here, ultra-stretchable starch-based hydrogels (amylopectin/polyacrylamide, AAM) are developed by constructing reversible intramolecular physical interactions. This strategy endows the hydrogel with exceedingly ultrahigh deformation due to a continuous hydrogen bonding network. It can be stretched from less than 0.5 to >300 cm without breakage that the elongation exceeds 600 times the original length. The elongation collected by the universal testing machine reaches up to 36 000% without breakage outperforming previous reports and demonstrating extraordinary stretchability. Furthermore, an interwoven structure of hydrogen bonding interaction and trace covalent bonds make the stress of hydrogel reach 0.28 MPa, accompanied by an ultra-high strain of 22 500% and significant toughness (47 MJ·m⁻³). The hydrogel displays high transparency (≈93%), low-temperature resistance, moisturizing property, and extraordinary interfacial adhesion property. Intriguingly, the aqueous precursor can act as inks to prepare various forms of hydrogel within minutes through the facile writing or drawing method. This hydrogel verifies strong potential in both fields of human motion sensor (After long-term or low-temperature conditions) and energy storage. This study will facilitate the progress of ultra-stretchable or multifunctional hydrogels.