Yield‐Stress Composite Fluids With High Thermal Conductivity and Tunable Rheology via Hierarchical Filler Architecture

Why It Matters

The material overcomes the traditional trade‑off between rheology and thermal performance, enabling reliable, reconfigurable cooling solutions in advanced devices.

Key Takeaways

• Hierarchical AlN particles create percolated thermal pathways
• Viscosity as low as 731.3 Pa·s at 10 s⁻¹
• Yield stress tunable from 37.3 to 802.3 Pa
• Thermal conductivity reaches 12 W·m⁻¹·K⁻¹
• Fluid switches between solid-like and liquid-like under shear

Pulse Analysis

Yield‑stress fluids have attracted attention for their ability to transition between solid‑like and liquid‑like states, yet their use in thermal management has been limited by low conductivity and high viscosity. By arranging aluminum nitride particles in a hierarchical, multi‑scale network within a silicone matrix, researchers create continuous heat‑transfer pathways while preserving the fluid’s thixotropic nature. This design sidesteps the conventional compromise: the small particles fill gaps between larger ones, forming a percolated lattice that conducts heat efficiently without locking the matrix into a rigid, high‑viscosity state.

The experimental results are striking. The composite exhibits a viscosity of just 731 Pa·s at a shear rate of 10 s⁻¹, comparable to many conventional greases, yet its yield stress can be tuned across an order of magnitude—from 37 Pa for easy flow to over 800 Pa for structural stability. Thermal conductivity peaks at 12 W·m⁻¹·K⁻¹, rivaling solid metal‑based interfaces. Advanced rheological testing shows rapid thixotropic recovery, and physics‑informed neural network models accurately predict the network’s breakdown and reformation dynamics. Such predictability simplifies integration into manufacturing processes where precise dispensing and long‑term reliability are critical.

For the electronics industry, the implications are immediate. High‑power processors, power‑electronics modules, and emerging quantum devices demand thermal interface materials that can be applied easily yet remain mechanically robust over years of operation. This yield‑stress fluid can be pumped or printed in its liquid state, then solidify in situ to maintain low thermal resistance and prevent pump‑out under vibration. Its reconfigurable nature also opens pathways for adaptive cooling systems that respond to load fluctuations. As device architectures become more compact, materials that blend fluidic processing with solid‑state performance, like this hierarchical AlN‑PDMS composite, are poised to become a cornerstone of next‑generation thermal management strategies.