High‐Enthalpy Solid–Solid Phase Change Composite Constructed From Physical Entanglements for Multimodal Thermal Managements, Thermal‐Induced Shape Memory, and Motion Sensing

ABSTRACT The thermal management systems of advanced equipment operating under complex conditions impose stringent requirements on phase change materials (PCMs) to possess both high energy storage density and active regulation capabilities. Solid–liquid PCMs (SLPCMs) suffer from severe liquid leakage, whereas chemical cross‐linking strategies inevitably sacrifice latent heat storage capacity. Therefore, this work proposes a folding‐hot‐pressing process based on physical entanglements, successfully constructing a multifunctional solid–solid PCM composite. This composite relies on the physical chain entanglement of ultrahigh‐molecular‐weight polyethylene glycol (HPEG) with low‐molecular‐weight PEG (LPEG), synergistically coupled with carbon nanotubes (CNTs). This structure effectively suppresses macroscopic liquid leakage while preserving the intrinsic phase‐change energy storage capability of the skeleton, yielding a high phase‐change enthalpy of 158.0 J g −1 . Furthermore, the dispersion of CNTs establishes continuous thermally and electrically conductive networks within the polymer matrix, achieving remarkable photo/electro‐thermal conversion efficiencies of 92.1% and 91.2%, respectively. Under high‐temperature conditions, the entangled polymer network exhibits rubber‐like elasticity, endowing it with reliable shape programmability and dynamic strain‐sensing capability with a gauge factor (GF) of 1.36. Through the synergistic coupling of passive heat storage, active heating, and real‐time motion monitoring, this integrated composite provides a highly adaptable thermal management solution for specialized robotics and advanced electronic systems in extreme environments.