Lightweight Liquid Metal‐Elastomer Foam with Smart Multi‐Function

Lightweight metal‐polymer composited foam has drawn considerable attention in fields of wearable electronics, acoustic and electromagnetic shielding, automotive and aerospace manufacturing, owing to its unique advantages like electrical conductivity and mechanical properties. Herein, a facile strategy is studied for one‐step fabrication of multifunctional liquid metal (LM) permeated expancel microspheres foam (EMLM foam) with controllable shape and size. Specifically, the formation process and mechanism of bicontinuous structure with polymer and liquid metal are explored by real‐time monitoring and finite element simulation. Both experimental and simulating results confirmed a stable 3D metal interconnected network that can be constructed with lower limit of LM (3 vol.%). In addition, based on the unique features of reversible rigidity control, lightweight, electrical conductivity, and mechanical stability, the EMLM foam can exhibit intelligent performance in tunable acoustic, energy absorption, and thermal driving repair. Combined with EMLM foam's facile preparation process and versatility, it can provide the remarkable opportunity to develop the lightweight intelligent devices. An inside to outside strategy is proposed for one‐step fabrication of lightweight foam (density