Ordered nanoplastic-elastomer networks resolve conflict between softness and stability.

Abstract

Soft materials often fail through snap-through instability, where a small increase in load causes a sudden, catastrophic deformation. However, overcoming this instability requires a polymer network of two seemingly contradictory behaviors: softness at small strains to allow deformation, but early stiffening at afterward strains to prevent instability. Here we resolve this conflict by designing an architecture of ordered nanoplastic-elastomer network. We identify two design principles: a small volume fraction of rigid plastic nanodomains is orderly arranged within a soft elastomer matrix; the nanodomains and matrix are strongly linked by covalent bonds. These features together produce a crucial effect: macroscale strain is greatly amplified at the microscale, inducing earlier stiffening while retaining small-strain softness. Theoretically and experimentally, we demonstrate that this network architecture can prevent notorious premature failure in dielectric elastomer actuators, and greatly enhance the actuation performance. These results suggest a general route to design soft materials that resist catastrophic instability-induced failure.