Hydrogen‐Bonding Affords Sustainable Plastics with Ultrahigh Robustness and Water‐Assisted Arbitrarily Shape Engineering

Abstract Herein, the supramolecular plastic‐like hydrogel (SPH) is introduced as a platform to fabricate sustainable plastics with ultrahigh stiffness and strength as well as water‐assisted arbitrarily shapeable capability. The transparent plastics are constructed from SPHs of cellulose ether/polycarboxylic acid complexes and demonstrate mechanical robustness with Young's modulus up to 3.4 GPa and tensile strength up to 124.0 MPa, superior or comparable to most common plastics. Meanwhile, the shape of the plastics can be reversibly engineered by air drying of the SPHs with diverse 2D/3D shapes and structures, which are generated conveniently via origami, kirigami, embossing, etc., in virtue of plastic deformation and shape memory effect of SPHs. On the basis of multi‐dimensional infrared‐spectral analysis, it is revealed that the dense acid–acid and acid–ether hydrogen (H)‐bonding network in the plastic is responsible for the mechanical robustness while the evolution of water–polymer H‐bonds into polymer–polymer H‐bonds during air drying contributes to the shape fixing. This work provides a novel method of manufacturing sustainable plastics with simultaneous strong mechanical performance and convenient processibility from hydrogels with plastic‐like mechanical behavior.