Engineering Poly(ionic liquid) Composites for Silicone-Free Thermal Interface Materials: Enhanced Thermal Conductivity and Interfacial Adhesion

The rapid advancement of artificial intelligence, coupled with increasing device miniaturization and power density, has made thermal management a critical bottleneck limiting reliability and performance. Thermal interface materials (TIMs), which bridge chips and heat sinks, are essential in reducing thermal resistance. Silicone-based TIMs, despite their widespread use, suffer from weak interfacial bonding, micropore expansion, and delamination under thermal stress, undermining long-term reliability. This study proposes a novel silicon-free TIM system based on poly(ionic liquid)s (PILs), which systematically addresses the interfacial adhesion and thermal stability limitations. Poly(1-dodecyl-3-vinylimidazolium) bis(trifluoromethylsulfonyl)imide (P[lm₁₂V]TFSI) exhibits strong interfacial adhesion to metal and semiconductor substrates (5.52 MPa for Cu and 3.92 MPa for Si), with a 5% weight-loss decomposition temperature reaching 280 °C, and reversible ionic bonding that enables self-healing and recyclability. To further enhance thermal conductivity, a dual-particle filler strategy employing high-sphericity silver particles was adopted. The resulting P[lm₁₂V]TFSI/Ag composite exhibited a thermal conductivity of 17.2 W m^-1 K^-1 at 80 vol % loading, while maintaining robust interfacial adhesion (1.19 MPa on Si and 1.26 MPa on Cu). The material demonstrates exceptional interfacial compliance, thermal conductivity, and processing durability, presenting a disruptive solution for thermal management in electronics.