Dynamic Percolation Networks Engineered Low Curie Temperature PTC Composites for Self-Adaptive Thermal Management
Polymer-based positive temperature coefficient (PTC) composites exhibit temperature-responsive resistivity, yet conventional systems with Curie temperatures (Tc) above 50 °C fail to meet the precision thermal management demands of room-temperature electronics. This study presents a ternary composite wherein carbon black (CB) is selectively localized within a myristyl alcohol (MA) phase, stabilized by an ethylene vinyl acetate (EVA) matrix. The reversible solid-liquid transition of MA dynamically disrupts and reconfigures CB conductive networks, while EVA elasticity suppresses phase migration at elevated temperatures. The optimized MA/EVA/CB composite achieves a low Tc of 35 °C, ultralow initial resistivity (ρin) of 50 Ω cm, high PTC intensity (PTCI = 7.0), and exceptional cycling stability with >95% resistivity retention after 100 thermal cycles. Even after 14 days of real space-environment exposure, the composite maintains ultralow resistivity and high PTCI. Differential scanning calorimetry and Fourier-transform infrared spectroscopy confirm molecular integrity under extreme conditions. Microstructural analysis reveals that MA melting/crystallization governs conductive network disruption and reconfiguration. A self-regulating heater fabricated from this composite stabilizes an aluminum block at 30.6 ± 0.03 °C under 20 V in a −10 °C environment without external control. These low-Tc PTC composites offer transformative potential for adaptive thermal management in aerospace electronics.