Ultra-highly electrically insulating carbon materials and their use for thermally conductive and electrically insulating polymer composites

Anisotropic carbon materials such as carbon nanotubes (CNTs) and carbon fibers exhibit extremely high thermal conductivity (TC). However, due to their high electrical conductivity, they have not been used in applications that require both high TC and electrical insulation. Herein, ultra-highly electrically insulating CNTs were prepared by layer-by-layer self-assembly method using various oxide nanomaterials (ONMs) such as titania nanosheets, silica nanoparticles, and water glasses (WGs). ONM-coated CNTs (ONM-CNTs) showed high surface resistivity and ultra-high volume resistivity in acrylate polymer matrices (similar to 10(17) Omega cm) even at high CNT loadings (similar to 10 vol%). WG-coated CNTs (WG-CNTs) after calcination exhibited the highest heat resistance, showing high electrical insulation even after heat treatment at 500 degrees C under air. WG-CNTs were stable in the poly (1,4-phenylenesulfide) (PPS) matrix during melt-mixing at high temperature (300 degrees C), giving the WG-CNT/PPS composites with extremely high volume resistivity (>= 10(15) Omega cm) even at high WG-CNT loadings (similar to 16.7 vol%) and enhanced through-plane TC (similar to 2.0 W m(-1) K-1). The TC is much superior to those of previously reported CNT/polymer composites with electrical insulation (<= 0.57 W m(-1) K-1). This method is scalable, nondestructive, and applicable to various carbon materials. The presented approach is promising for preparing electrically insulating materials for various thermal management applications. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Anisotropic carbon materials like carbon nanotubes (CNTs) with high thermal conductivity have been modified to exhibit high electrical insulation and heat resistance through layer-by-layer self-assembly with oxide nanomaterials (ONMs). This method enables the preparation of electrically insulating CNTs with enhanced through-plane thermal conductivity for various carbon materials and thermal management applications.