Mechanical enhancements and structural simulation of reactive poly(ethylene glycol) and cellulose nanocrystals to polyacrylamide hydrogels

Hydrogels have gained increasing attentions on account of their “soft and wet” nature, but the inherent low mechanical performance and poor structural stability severely limits their practical application. Herein, a hybrid method was developed to achieve the reinforcement of polyacrylamide (PAM) based on grafting with polyethylene glycol diglycidyl ether (PEGDE) and combination with amination-modified cellulose nanocrystals (ACNCs). By constructing the PEGDE and MBAA dually cross-linked PAM hydrogel, its energy dissipation efficiency was increased by 4.6 times. The flexible PEGDE chain effectively realizes the dissipation of mechanical energy and the optimal distribution of stress, even in the swollen state. Furthermore, the incorporation of ACNC effectively facilitates the development of a polymer-nanoparticle composite architecture. The result demonstrated that ACNC-reinforced hydrogel achieves a three-fold improvement in both mechanical stiffness and energy dissipation capacity. ACNC and PEGDE form a chain-entangled network via covalent bonding, while the “sacrificial bond”-like structures constructed on their surfaces exhibit a unique energy dissipation mechanism, as further clarified by structural simulations. Moreover, the hydrogels demonstrated minimal cytotoxicity toward mammalian cells, demonstrating excellent biocompatibility. The proposed strategy of this study is expected to inspire the researchers to design structural or load-bearing hydrogels for potential biomedical applications.