Cold, Rapid, and Scalable Stamping of Aramid-Networked Viscoelastic h-BN Doughs for Complex Thermal Architectures

Extensive efforts have been made to fabricate complex 3D thermal management materials from hexagonal boron nitride (h-BN) using 3D printing and templating. However, these techniques are often energy-intensive, time-consuming, and inherently limited in scalability, owing to prolonged processing times and low throughput. Herein, we report a cold, rapid, and scalable stamping approach for constructing intricate, large-area h-BN-based thermal architectures. This strategy relies on forming highly viscoelastic h-BN doughs achieved through developing a para-aramid (p-aramid) fiber network and densification via a bimodal alumina mixture. The p-aramid network maximizes viscoelasticity with a minimal binder content (5.1 wt.%), enabling the doughs to exhibit pronounced plasticity during stamping while maintaining solid-like behavior after relaxation. Consequently, the doughs conform precisely to complex stamp geometries within 2 s under ambient conditions, preserving their high structural integrity. Scalability is demonstrated by stamping various 3D geometries exceeding 10 cm, including cubes, cylinders, annular sectors, and honeycombs. Furthermore, the fiber-reinforced structures exhibit enhanced thermal conductivity (TC) and fatigue resistance under extreme temperatures (- 50°C and 200°C). Notably, the resulting architectures substantially improve the TC of the polymer composites when used as internal frameworks. This low-energy stamping strategy represents a paradigm shift in the processing of advanced thermal materials.