Preparation and characterization of mechanically robust and thermo-responsive hydrogel inspired by spring-like structure.

Poor mechanical properties of PMAD (the copolymer of AM, AA and DMC) hydrogel derived from its high-density rigid crosslinking structure is main obstacle for its functional application. Herein, inspired by spring-like structure, nano-SiO 2 based crosslinker was used to fabricate mechanical robust thermo-responsive PMAD-matrix hydrogel. Nano-SiO 2 was modified with poly (ethylene imine) (PEI), which was further introduced in crosslinking network of PMAD hydrogel. Flexible PEI chains can elongate under stress, which endows crosslinking network deformability, like that of spring in tension. Meanwhile, nano-SiO 2 can improve the tensile strength of the hydrogel, and amino groups in PEI can improve its dispersity in water. When content of the crosslinker is 15‰, tensile strength and elongation at break can be improved by nearly 3540% and 503% respectively owing to synergistic effect of PEI and SiO 2. More interesting, mechanical properties of hydrogels can be designed flexibly by controlling the structure of the nano-SiO 2 based crosslinker, which realizes structure management of hydrogel. Moreover, hydrogel prepared by this method also shows thermo-responsivity, endowing it potential for functional application. [Display omitted] • Novel crosslinker SiO 2 -PEI-AGE inspired by spring-like structure was synthesized. • Synergistic effect of SiO 2 and PEI can improve both strength and fracture. • Tensile strength and elongation of PMAD can be increased by 3540% and 503%. • Structure management of PMAD can be realized by structure control of SiO 2 -PEI-AGE. • PMAD hydrogel prepared by this method also shows UCST thermo-responsivity. [ABSTRACT FROM AUTHOR]