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As one of the emerging nanomaterials, boron nitride nanotubes (BNNTs) provide promising opportunities for diverse applications due to their unique properties, such as high thermal conductivity, immense inertness, and high-temperature durability, while the instability of BNNTs due to their high surface induces agglomerates susceptible to the loss of their advantages. Therefore, the proper functionalization of BNNTs is crucial to highlight their fundamental characteristics. Herein, a simplistic low-cost approach of BNNT surface modification through catechol-polyamine (CAPA) interfacial polymerization is postulated to improve its dispersibility on the polymeric matrix. The modified BNNT was assimilated as a filler additive with AlN/Al2O3 filling materials in a PDMS polymeric matrix to prepare a thermal interface material (TIM). The resulting composite exhibits a heightened isotropic thermal conductivity of 8.10 W/mK, which is a ~47.27% increase compared to pristine composite 5.50 W/mK, and this can be ascribed to the improved BNNT dispersion forming interconnected phonon pathways and the thermal interface resistance reduction due to its augmented compatibility with the polymeric matrix. Moreover, the fabricated composite manifests a fire resistance improvement of ~10% in LOI relative to the neat composite sample, which can be correlated to the thermal stability shift in the TGA and DTA data. An enhancement in thermal permanence is stipulated due to a melting point (Tm) shift of ∼38.5 °C upon the integration of BNNT-CAPA. This improvement can be associated with the good distribution and adhesion of BNNT-CAPA in the polymeric matrix, integrated with its inherent thermal stability, good charring capability, and free radical scavenging effect due to the presence of CAPA on its surface. This study offers new insights into BNNT utilization and its corresponding incorporation into the polymeric matrix, which provides a prospective direction in the preparation of multifunctional materials for electric devices. [ABSTRACT FROM AUTHOR]

Over the past few years, the ability to efficiently increase boron nitride nanotube (BNNT) production has opened up ample research possibilities. BNNT has garnered significant attention for diversifying its industrial applications. However, the problem of poor processability resulting from agglomeration and uneven distribution has emerged as a major challenge to integrating BNNT into the polymer matrix for composite material formation. Utilizing noncovalently attached molecules with various reactive sites can be a logical method to enhance the compatibility of BNNT with different polymers. The present study explored a simple approach to protruding BNNT onto the surface of Al 2 O 3 through tannic acid (TA)-assisted generation of alkyl chains (octadecylamine, ODA) to fabricate Al 2 O 3 @ODA-BNNT. The subsequent compounding of Al 2 O 3 @ODA-BNNT with epoxy polymer generates interconnected thermal conduction pathways, thereby improving the thermal conduction and mechanical performance of the composites. The current research approach allows for the even distribution of BNNT throughout the polymer matrix, as demonstrated by optical characterization, mechanical performance analysis, and isotropic thermal conductivity analysis. The fabricated epoxy composite by incorporating a 2 wt % (BNNT = 1.3 wt % and ODA = 0.7 wt %) ODA-BNNT exhibited 5.117 W/mK thermal conductivity and 7.43 MPa mechanical stress. Thermal conductivity improved by 2528, 76.56, and 54.7%, while mechanical stress enhanced by 270, 221, and 34% compared to neat polymers without BNNT and virgin BNNT epoxy composites, respectively., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)