Lightweight and High‐Strength Phase Change Composites Based on 3D‐Printable Pickering Emulsions

ABSTRACT The combination of 3D‐printing technology with Pickering emulsion encapsulated phase change materials (PCMs) is a state‐of‐the‐art approach to address the challenges of liquid‐phase leakage and complex fabrication in traditional PCMs. However, the development of this technology is limited by the inherent trade‐off among energy storage density, rheological properties, and mechanical strength. Herein, we report a unified synergistic strategy that successfully decouples the aforementioned properties by introducing vinyl acetate (VAc) as a polymerizable active diluent with the dual functions of rheological modulation and subsequent structural construction. This diluent optimizes the rheological properties of the Pickering emulsion to enable excellent printability. Building upon this foundation, we design a dual in situ polymerization mechanism to simultaneously construct both protective inner shells for the PCM microcapsules and a reinforcing crosslinked matrix network during the printing process. This synergistic inner‐shell‐outer‐network architecture endows the printed devices with extraordinary mechanical stability, allowing them to simultaneously maintain a high energy storage density (up to 110.5 J g − 1 ) and achieve a compressive strength of 8.32 MPa, sufficient to withstand more than 50 000 times its own weight. This technology opens a new avenue for the additive manufacturing of multifunctional devices that integrate both energy storage and load‐bearing capabilities.