Research on the design, fabrication, and application of double network (DN) hydrogels, assembled from pairs of polymers, has grown recently due to their unique structural, physicochemical, and functional properties. DN hydrogels can be designed to exhibit a broader range of functional attributes than single network (SN) ones, which extends their applications in various fields. There has been strong interest in the development of biopolymer DN hydrogels because of their environmental, sustainability, and safety benefits. However, there is limited knowledge on the formation and application of these novel materials. This article reviews the principles underlying the design and fabrication of hydrogels using different crosslinking approaches, including covalent and/or non-covalent bonding, and the formation mechanisms, network structures, and functional attributes of different DN hydrogels. The impact of polymer composition, structural organization, and bonding on the mechanical and functional properties of DN hydrogels is reviewed. Potential applications of these hydrogels are highlighted, including in tissue engineering, biomedicines, and foods. The functional attributes of DN hydrogels can be tailored to each of these applications by careful selection of the biopolymers and crosslinking mechanisms used to assemble them. Finally, areas where further research are needed to overcome the current limitations of DN hydrogels are highlighted.

由于其独特的结构、物理化学和功能特性，由成对聚合物组装而成的双网络（DN）水凝胶的设计、制造和应用研究近年来不断发展。DN 水凝胶可以设计成比单网络（SN）水凝胶表现出更广泛的功能属性，这扩展了它们在各个领域的应用。由于生物聚合物 DN 水凝胶的环境、可持续性和安全性优势，人们对其开发产生了浓厚的兴趣。然而，人们对这些新型材料的形成和应用的了解有限。本文回顾了使用不同交联方法（包括共价和/或非共价键合）设计和制造水凝胶的原理，以及不同 DN 水凝胶的形成机制、网络结构和功能属性。综述了聚合物组成、结构组织和键合对 DN 水凝胶机械和功能性能的影响。强调了这些水凝胶的潜在应用，包括在组织工程、生物医学和食品中。通过仔细选择生物聚合物和用于组装它们的交联机制，DN 水凝胶的功能属性可以根据这些应用进行定制。最后，强调了需要进一步研究以克服 DN 水凝胶当前局限性的领域。