Switching between Elasticity and Plasticity by Network Strength Competition.

Switching a material between highly elastic and plastic would be of great use in many fields but has proven to be extremely challenging. Here, the use of mechanical strength competition between two networks in a hybrid material is reported to switch between elasticity and plasticity. In a gel material composed of an elastic polymer network and a shear-thinning nanofiber network, the excellent elasticity of the gel is demonstrated when the former is stronger than the latter. In contrast, the gel exhibits an extraordinary plasticity, which can be stretched to form a permanent anisotropic and tough gel due to the orientation of the nanofibers. The mechanical strength of each network can be simply tuned by adjusting either the crosslinking density or the loading of the nanofibers. This work may open a window to transform a material between superior elastic and plastic, which is useful for the development of adaptable materials.