Based on the tough double-network hydrogel, a further crosslinked DN network hydrogel was developed and named joint double network (JDN) hydrogel. The JDN hydrogel consisting of ionically cross-linked sodium alginate (SA) as the first network, the chemically cross-linked poly (acrylamide-acrylic acid) (PAMAAc) as the second network and both of them combined together by ferric ions. As a result, SA/PAMAAc-Fe³⁺ hydrogels exhibited high mechanical strength with tensile stress of 1.26 MPa and tensile strain of 653%. Ultraviolet–visible spectroscopy, rheological and swelling tests also illustrated that the JDN structure greatly improved the mechanical properties of hydrogels because of close integration of internal networks. Moreover, the SA/PAMAAc-Fe³⁺ JDN hydrogel also owned high water content of 85%, free-plasticity, and excellent electrical property, which allowed it to be easily molded various shapes for tough electronic devices, flexible electrodes, and wearable equipment.

在坚韧的双网络水凝胶的基础上，进一步开发了交联的DN网络水凝胶，并将其命名为“联合双网络（JDN）”水凝胶。JDN水凝胶由离子交联的藻酸钠（SA）作为第一个网络，化学交联的聚（丙烯酰胺-丙烯酸）（PAMAAc）作为第二个网络，并且两者通过三价铁离子结合在一起。结果，SA / PAMAAc-Fe ³⁺水凝胶显示出高机械强度，拉伸应力为1.26 MPa，拉伸应变为653％。紫外可见光谱法，流变学和溶胀试验还表明，由于内部网络的紧密结合，JDN结构极大地改善了水凝胶的机械性能。此外，SA / PAMAAc-Fe ³⁺ JDN水凝胶还具有85％的高水含量，自由塑性和出色的电性能，这使其可以轻松地成型各种形状，以用于坚硬的电子设备，柔性电极和可穿戴设备。