It remains challenging to develop hydrogels with comprehensive mechanical properties including ultrahigh strength, toughness and rapid self-recovery. Herein, dual physical crosslinking strategy was used to develop novel nanocomposite hydrogels reinforced… Click to show full abstract
It remains challenging to develop hydrogels with comprehensive mechanical properties including ultrahigh strength, toughness and rapid self-recovery. Herein, dual physical crosslinking strategy was used to develop novel nanocomposite hydrogels reinforced by poly(N-vinylpyrrolidone) grafted cellulose nanocrystal (CNC-g-PVP). The hydrogels were fabricated via in situ copolymerization of acrylic acid (AA) and acrylamide (AM) in presence of CNC-g-PVP and subsequent introduction of Fe3+ ions. CNC-g-PVP induced the first crosslinking through strong cooperative hydrogen bonds existing between PVP chains grafted onto CNCs and amide groups from P(AM-co-AA) chains. Fe3+ triggered the second crosslinking by forming coordination bonds with –COO− groups. The cooperative hydrogen bonds enhanced the interfacial compatibility between CNC-g-PVP nanofillers and hydrogel matrix, and served as fast recoverable sacrificial bonds. As a result, the hydrogels exhibited high tensile strength (1.89–2.51 MPa), remarkable toughness (6.01–6.81 MJ/m3), rapid self-recovery (83.4–97.8% recovery of hysteresis loop within 5 min) and favourable fatigue resistance.
               
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