writer：Xiaoqiang, Qiang Chen* and Jie Zheng*, et al.
keywords：Double network hydrogels
source：期刊
specific source：J Mater Chem B
Issue time：2017年
Double network (DN) hydrogels composed of two different polymer networks with strong asymmetry are excellent structural platforms to integrate different mechanical properties into a single material. However, simultaneously achieving high strength and self-healing property in DN hydrogels still remain a challenge. In this work, we design and synthesize Gelatin/Polyacrylamide (Gelatin/PAAm) DN gels by combining a thermo-reversible and physically crosslinked gelatin as the first network and a covalently crosslinked PAAm as the second network. The optimal Gelatin/PAAm DN gels demonstrated high mechanical properties (E of 84 kPa, σf of 0.268 MPa, εf of 40.69 mm/mm and W of 6.01 MJ/m3), large hysteresis (up to 1012 kJ/m3 at λ =30), and rapid self-recovery property (~87% toughness recovery at room temperature). These superior properties were largely attributed to effective energy dissipation via the rupture of gelatin first network. Most interestingly, Gelatin/PAAm DN gels without any chemical crosslinker in the second network enable to achieve both high mechanical strength and fast self-healing property. By modulating heating temperatures and healing times, the healed Gelatin/PAAm gels can achieve 53% healing efficiency at a physiological temperature range, which greatly expands its uses for biomedical applications. The combination of high strength, self-recovery, and self-healing properties makes Gelatin/PAAm gels as promising candidates for further development as thermoresponsive biomaterials used in physiological conditions.