Stretch-activated morphing enabled by integrated physical–chemical network engineering

Abstract

Mechanical stimuli-responsive shape transformations, exemplified by mimosa leaves, are widespread in nature, yet remain challenging to realize through facile fabrication in synthetic morphing materials. Herein, we demonstrate stretch-activated shape-morphing enabled by an elastic–plastic bilayer structure assembled via dynamic crosslinking. Through dioxaborolane metathesis, a dynamic, crosslinked polyolefin elastomer (POEV) with elasticity and a co-crosslinked POE/paraffin wax blend (POE/PW-V) with tunable plasticity are prepared. An elastic–plastic mismatched bilayer is then assembled via dioxaborolane metathesis at the interface. Upon stretching and release, the elastic POEV layer attempts to recover, while the plastic POE/PW-V layer resists recovery, inducing curled deformation of the bilayer strips. The localized bilayer design allows for selective activation and region-specific shape transformation under tensile stress, enabling the creation of customizable morphing geometries. Moreover, the low-entropy conformation fixed during stretching spontaneously reverts to a high-entropy state upon heating-induced melting of PW crystals, thereby restoring the original shape. This thermally induced recovery ensures repeatable stretch activation. This work presents a design strategy that integrates physical and chemical network engineering to develop heterogeneously responsive systems, offering promising potential for soft morphing device applications.