Biphasic GaIn Alloy Constructed Stable Percolation Network in Polymer Composites over Ultrabroad Temperature Region

Abstract Flexible and adaptable polymer composites with high‐performance reliability over wide temperature range are imperative for various applications. However, the distinct filler‐matrix thermomechanical behaviors often cause severe structure damage and performance degradation upon large thermal shock. To address this issue, a general strategy is proposed to construct leakage‐free, self‐adaptive, stable percolation networks in polymer composites over wide temperature (77–473 K) with biphasic Ga₃₅In₆₅ alloy. The in situ micro‐CT technology, for the first time, reveals the conformable phase transitions of Ga₃₅In₆₅ alloys in the polymer matrix that help repair the disruptive conductive networks over large temperature variations. The cryo‐expanded Ga compensates the disruptive carbon networks at low temperatures, and flowable Ga and melted In at high temperatures conformably fill and repair the deboned interfaces and yielded crevices. As a proof‐of‐concept, this temperature‐resistant composite demonstrates superb electrical conductivity and electromagnetic interference shielding properties and stability even after a large temperature shock (ΔT = 396 K). Furthermore, the superiority of the construction of temperature self‐adaptive networks within the composite enables them for additive manufacturing of application‐oriented components. This work offers helpful inspiration for developing high‐performance polymer composites for extreme‐temperature applications.