Simultaneously achieving ultrahigh thermal conductivity and enhanced fluidity in Highly-Filled Polymer composites

• Breaks filler-fluidity trade-off via precursor engineering and centrifugation. • Maintains a fluidity below 100 Pa·s even at a 78.57 vol% filler loading. • Achieves a high 4.96 W·m −1 ·K −1 thermal conductivity in acrylate-based composites. • Delivers reliable thermal stability and cooling efficiency for LED systems. The development of high-performance thermal conductive materials (TCMs) is fundamentally constrained by the intrinsic conflict between ultrahigh filler loading for thermal conductivity and the processability dictated by viscosity. While acrylate-based TCMs offer stability advantages in optical and silicon-sensitive electronics, their thermal conductivity remains inadequate (< 2 W·m −1 ·K −1 ). Herein, a synergistic centrifugation-driven densification strategy is introduced to decouple filler loading from viscosity constraints. This approach combines: (1) molecularly tailored surface modification of multi-scale Al 2 O 3 to minimize interfacial thermal resistance; (2) formulation of a low-viscosity precursor with moderate initial filler loading; (3) controlled centrifugation to spatially concentrate fillers into shear-aligned percolation networks. This method achieves an ultrahigh localized Al 2 O 3 loading of 78.57 vol% while maintaining exceptional macroscopic fluidity (viscosity < 100 Pa·s). The resultant acrylate-based TCM exhibits benchmark-level thermal conductivity of 4.96 W·m −1 ·K −1 , surpassing commercial counterparts by a substantial margin.