Properties of Thermoresponsive N-maleyl gelatin-co-P(N-isopropylacrylamide) hydrogel with ultrahigh mechanical strength and self-recovery

Thermo-responsive polymer hydrogels with superior strength and toughness are potential candidate materials in biomedical field, such as drug delivery system and tissue engineering. By introducing maleylgelatin (MAGEL) into the conventional PNIPAAm hydrogel, a series of composite P(NIPAAm-co-MAGEL) hydrogels with combined features were fabricated. Thermo-responsive behaviors, equilibrium swelling ratio (ESR), compression strength, tensile strength (TS) and elongation at-break (E), cyclic compression tests, and thermal stability properties of hydrogels with different amount of MAGEL were investigated. Experimental data indicated that the amount of MAGEL could modulate the mechanical property of the composite hydrogel. With the increase of the MAGEL contents from 0 to 50%, the composite hydrogel with relatively high water content possessed good compressive strength, tensile strength and stretrability. Only when the weight ratio of MAGEL/NIPAAm was 30:70, did the P(NIPAAm-co-MAGEL) have a homogeneous distribution and stable 3D networks which played a significant role in the properties of the hydrogels. Cyclic compression tests results indicated that P(NIPAAm-co-MAGEL) hydrogel had an excellent thermo-reversible ability. This research would expand the scope of the PNIPAAm hydrogel applications.