Enhanced thermal conductivity in boron nitride incorporated polyethylene/polymethyl methacrylate composites via double percolation structure

Abstract Due to the miniaturization, integration and multi‐functional development of contemporary electronic devices, there is a growing need for efficient thermal conductive composite materials. This study focuses on enhancing the dispersion of modified boron nitride (mBN) within a linear low‐density polyethylene (LLDPE) phase by incorporating LLDPE‐graft‐Aminomethylpyridine (LLDPE‐ g ‐Py) to non‐covalently modify BN. Additionally, polymethyl methacrylate (PMMA) and LLDPE polymers were introduced to create modified BN/LLDPE/PMMA (mBN/LLDPE/PMMA) composites with a double percolation structure. The co‐continuous structure of the polymer composites was observed by using scanning electron microscopy (SEM). By selectively locating the BN modified by LLDPE‐ g ‐Py within the LLDPE phase, the co‐continuous structure of the LLDPE/PMMA blend was upgraded to a double percolation structure. This double percolation structure establishes a dense and optimal heat transfer network within the polymer matrix. The thermal conductivity of the mBN/LLDPE/PMMA composite with BN loading of 40 wt% was significantly increased to 1.12 Wm −1 K −1 , which was 350% higher than that of pure LLDPE, 38% higher than that of the BN/LLDPE composite, and 17% higher than that of the BN/LLDPE/PMMA composite. This study offers valuable insights into non‐covalent modification techniques for BN and the design of double percolation structures in thermal conductive polymer composites. Highlights The double percolation structure was successfully constructed by simple melt blending method with LLDPE and PMMA as matrix and BN as thermal conductive filler. The double percolation structure can significantly promote the efficiency of heat transfer inside the thermal conductive composites. A novel non‐covalent modifier LLDPE‐ g ‐Py was prepared to modify the surface of BN, and the selective localization of modified BN (mBN) in the LLDPE phase was realized.