Toughening Mechanism of Double Network Gels and New Research Trends

Abstract

In 2003, we developed Double Network (DN) hydrogels that achieved toughening by a completely different principle from previously existed rubbery materials. DN gel is composed of two interpenetrated networks with highly contrasting topological structure. One network is rigid and brittle from highly pre-stretched and densely crosslinked polymer, and the other network is soft and stretchable from coiled and sparsely crosslinked polymer. Interestingly, DN gel exhibits toughness comparable to natural cartilage despite of low internal friction of the material. In this review, we describe the points that have been clarified about the toughening mechanism of DN gel, after that, we also outline the latest research trends on the novel tough materials development based on the double network concept.