Stretchable conductive shape-memory nanocomposites for programmable electronics via photo-mediated multiscale structural design

Conductive shape-memory nanocomposites are very promising in flexible electronics, soft robotics, wearable sensors, etc. However, achieving a balance between conductivity, shape-memory behavior, and stretchability is still challenging in this field. Here, we report stretchable conductive shape-memory nanocomposites (SCSMNCs) prepared through photo-mediated multiscale structural design (PMMSD). At a molecular level, we utilize highly efficient photo-mediated radical polymerization and hydrogen abstraction reaction to fast construct a conjoined polymeric network in one step (∼68 s). Hybrid nanofibers are, meanwhile, introduced to generate highly conductive networks. This rational design facilitates the fabrication of nanocomposites simultaneously exhibiting excellent shape-memory behavior, high conductivity, improved mechanical properties, and rapid gelation. Mechanics-guided metamaterial design can be then produced in macro-scale by additive manufacturing to further increase the stretchability of the nanocomposites without compromising other key properties. Consequently, benefitting from the PMMSD strategy, the stretching strain of SCSMNCs improves significantly by 19 times compared to the samples lacking network and structural design, with conductivity > 10⁵ S/m, shape fixation ratio and shape recovery ratio > 95 %. Notably, the combination of the increased stretchability, high conductivity and excellent shape-memory behavior endows the SCSMNCs with adaptive electrical and mechanical properties over long ranges. Based on these advanced performances, we demonstrate the utility of the designed SCSMNCs as function-programmable electromagnetic interference shields and wearable sensors. We anticipate this study will pave a new way for the design and application of high-performance SCSMNCs.