One-Component Dual Actuation: Poly(NIPAM) Can Actuate to Stable 3D Forms with Reversible Size Change

A rare example of a one-component dual actuator is provided, which displays irreversible change in shape by rolling on contact with water and reversible size change on changing the temperature. The actuator has a bilayer structure with aligned and randomly oriented fibers of poly(N-isopropyl acrylamide). A combination of anisotropic E modulus and temperature dependent swelling/shrinkage provides the dual actuation.