Liquid crystal polyarylate tailored functionalized boron nitride alignment for constructing high thermal conductivity composites

Abstract

With the rapid development of high-frequency electronic devices toward greater integration and power density, electronic packaging materials that simultaneously offer high thermal conductivity and low dielectric loss are urgently needed. However, constructing an effective thermal conduction network typically requires high filler loadings, which in turn increase interfacial thermal resistance and raise dielectric loss. To address this challenge, a strategy is proposed that utilizes the liquid crystal orientation behavior of thermotropic liquid crystal polyarylate (LCP) to control the ordered arrangement of functionalized boron nitride (BN-G). During melt processing, highly oriented LCP molecular chains form in-situ microfibrillar structures along the shear flow direction, which align BN-G and facilitate continuous thermal conduction pathways at low filler loadings. These results demonstrate that BN-G is uniformly distributed in an ordered fashion along the in-plane direction within the LCP matrix. The LCP-BN-G composite with 20 wt% filler loading achieved an in-plane thermal conductivity of 1.45 W·m-1·K-1, representing a 196.5% increase over pure LCP, while maintaining a low dielectric constant of 3.36 and dissipation factor of 0.014 at 1 MHz. In summary, a feasible approach is provided herein for designing high-performance thermally conductive composites tailored for high-frequency and low-loss applications.