Design of Thermal Interface Materials with Excellent Interfacial Heat/Force Transfer Ability via Hierarchical Energy Dissipation

Abstract Interfaces play an important role in the heat and stress transfer within applications such as electronic cooling. The coexistence of apparently contradictory properties between heat dissipation and adhesion at interfaces poses a constant challenge for existing interface materials. Herein, a thermal interface material is reported, consisting of epoxy‐functionalized polydimethylsiloxane and aluminum fillers with excellent interfacial heat/force transfer ability. This material optimizes the combination of thermal conductivity of 3.46 W m⁻¹ K⁻¹ and adhesion energy of 1.17 kJ m⁻². Using two viscoelastic models, the excellent interfacial force transfer ability is attributed to a hierarchical energy dissipation via the introduction of borate ester bonds and the aluminum filler networks. A simple kinetic bond model demonstrates that the borate ester bonds increase molecular chain segment mobility, allowing full extension at debonding interface for stress dispersion and efficient energy dissipation. The aluminum filler networks not only facilitate thermal transfer, but also dissipate the mechanical energy during filler network destruction due to the bond breakage between fillers. The excellent heat dispassion and mechanical stability are further demonstrated when this thermal interface material is used in flexible light emitting diodes and high‐power chips. This work provides a new strategy for balancing interfacial heat and force transfer.