Dynamic percolation networks engineered low Curie temperature PTC composites for self-adaptive thermal management

Polymer-based positive temperature coefficient (PTC) composites show exceptional potential for smart thermal management owing to temperature-responsive resistivity. However, conventional PTC composites with high Curie temperatures ( T c > 50 °C) are unsuitable for precision electronics requiring room-temperature operation. The development of low-Tc composites ( T c < 50 °C) faces challenges in balancing electrical resistivity, stability, and sensitivity. We present a ternary composite design where carbon black (CB) is selectively dispersed in myristyl alcohol (MA) phase, stabilized by an ethylene vinyl acetate (EVA) matrix. The reversible solid-liquid transition of MA dynamically modulates CB conductive networks, while the elasticity of EVA suppresses phase migration under elevated thermal conditions. The MA/EVA/CB composite achieves unprecedented performance: low T c (35 °C), ultralow initial resistivity (50 Ω cm), high PTC intensity (7.0), and exceptional cycling stability (>95% resistivity retention after 100 thermal cycles), surpassing previous benchmarks. Even after real space-environment exposure for 14 days, it retains ultralow resistivity and high PTC intensity. DSC/FTIR analyses confirm molecular integrity, validating stability under extreme conditions. Microstructural studies reveal that MA phase melting/crystallization governs conductive network disruption/reconfiguration. A self-regulating heater fabricated from this composite stabilizes an aluminum block at near T c (30.6 ± 0.03 °C) at 20 V and −10 °C environments without external controls. The low- T c PTC composites demonstrate transformative potential in adaptive thermal management for aerospace electronics.