Spider-Silk-Inspired Heterogeneous Supramolecular Network with Strain-Stiffening, High Damping Capacity, and Supercontraction

Natural materials are adaptive with intriguing mechanical properties such as strain-stiffening, high damping, and stimuli-responsive actuation under ambient conditions, which are evolutionarily derived to adapt to variable environments. Such adaptabilities are highly desirable for advanced smart materials in soft robots and bionic applications yet rarely achieved all in one synthetic material. Inspired by the molecular chemistry and structure of spider silk, a structurally heterogeneous supramolecular network with all-round adaptabilities is developed by evaporation-induced self-assembly of hydrogen-bonded macromolecules. The supramolecular network consists of both hard (crystallites) and soft (amorphous) phases with dynamic hydrogen bonds, exhibiting strong strain, time, and hydration dependency with adaptive mechanical and structural responses to varying strain, deformation rate as well as moisture. Through multifunctional crosslinking, the network exhibits silk-like attributes with an extensibility of >130%, intense strain-stiffening (sixfold modulus enhancement), high damping capacity (>80%) over a wide range of strain rate, and moisture-triggered large supercontraction (contraction ratio of >50%). Artificial materials with such combined adaptiveness under bio-benign conditions are promising for applications in biomimetic and biomedical fields.