John A. Paulson School of Engineering and Applied Science, Harvard University, Cambridge, MA 02138, USA.
Sci Adv. 2023 Jun 30;9(26):eadh7742. doi: 10.1126/sciadv.adh7742.
Hydrogels are being developed to bear loads. Applications include artificial tendons and muscles, which require high strength to bear loads and low hysteresis to reduce energy loss. However, simultaneously achieving high strength and low hysteresis has been challenging. This challenge is met here by synthesizing hydrogels of arrested phase separation. Such a hydrogel has interpenetrating hydrophilic and hydrophobic networks, which separate into a water-rich phase and a water-poor phase. The two phases arrest at the microscale. The soft hydrophilic phase deconcentrates stress in the strong hydrophobic phase, leading to high strength. The two phases are elastic and adhere through topological entanglements, leading to low hysteresis. For example, a hydrogel of 76 weight % water, made of poly(ethyl acrylate) and poly(acrylic acid), achieves a tensile strength of 6.9 megapascals and a hysteresis of 16.6%. This combination of properties has not been realized among previously existing hydrogels.
水凝胶正在被开发出来以承受负载。其应用包括人造肌腱和肌肉，这些应用需要高强度来承受负载和低滞后性以减少能量损失。然而，同时实现高强度和低滞后性一直具有挑战性。通过合成相分离被阻止的水凝胶，这里就可以应对这一挑战。这种水凝胶具有互穿的亲水和疏水网络，这些网络会分离成富含水的相和贫水的相。这两个相在微观尺度上被阻止。柔软的亲水相在强疏水相上分散应力，从而导致高强度。这两个相具有弹性并通过拓扑缠结粘附，从而导致低滞后性。例如，由聚（丙烯酸乙酯）和聚（丙烯酸）制成的 76 重量%水的水凝胶，实现了 6.9 兆帕斯卡的拉伸强度和 16.6%的滞后性。这种性能组合在以前存在的水凝胶中尚未实现。
