Enhanced Thermal Conductivity in Polymer Nanocomposites via Covalent Functionalization of Boron Nitride Nanotubes with Short Polyethylene Chains for Heat-Transfer Applications

Abstract

Boron nitride, which possesses high thermal conductivity, is often incorporated into polymer matrixes for thermal management. The enhancement in the thermal conductivity depends on the filler shape, size, effective dispersion in the matrix, and interfacial thermal resistance between the filler and matrix, and the last two are the most challenging issues. To address these challenges, in this study two different covalent functionalization approaches on boron nitride nanotubes (BNNTs) with short polyethylene (PE) chains are employed: one based on the Williamson reaction and the other on nitrene [1 + 2] chemistry. The covalent connection between the nanotubes and the polymer is confirmed by Fourier transform infrared, X-ray photoelectron microscopy, tandem thermogravimetric−infrared spectroscopy analysis and energy-filtered transmission electron microscopy. The modification of BNNTs with short polymer chains has resulted in an excellent strategy to modulate the interface in polymer composites. Tuning the interface has a strong influence on thermal transport, and up to an ∼250% increase in the thermal conductivity of BNNT-HDPE nanocomposites has been observed when the loading increases from 20 to 40 wt % of PE-modified BNNTs due to the improved dispersion and reduced interfacial thermal resistance. The materials described here show the potential for heattransfer applications.

High pressure homogenization of graphene and carbon nanotube for thermal conductive polyethylene composite with a low filler content

“…As shown in Figure 8(b), this value is higher than that of most thermal‐conductive composites at a comparable amount of the fillers such as the carbon nanofiber reinforced polyethylene (CNF/PE), 37 graphene nanoplatelets filled polyethylene (GNPs/PE), 38 expanded graphite (EG/PE), 39 multilayer graphene enhanced silicone rubber (Fe 3 O 4 /MG/SR), 40 and so on 40–42 . It is even comparable to the thermal‐conductive composites made from high‐content Al 2 O 3 , 43 or BN 44,45 fillers. It suggested that the large size of dispersed graphene nanosheets are important for thermal conductive polymer composites.…”

Development and Challenges of Thermal Interface Materials: A Review

“…When the addition amount of the modified AlN was 25 wt%, the in-plane TC of the composite film reached 5.11 W m −1 K −1 . Quiles-Díaz et al [69] utilized two different covalent functionalization approaches on boron nitride nanotubes (BNNTs) with short polyethylene chain (Figure 2): Williamson reaction and Nitrene [1 + 2] chemistry. The filler had excellent compatibility with the high-density polyethylene matrix while maintaining the integrity of the nanotube.…”

“…Hydroxylated BNNT (BNNT-OH) is reacted with a bromine-terminated polyethylene (PE-Br); reaction of pristine BNNT and azide-terminated polyethylene (PE-N3). Reproduced with permission [69]. Copyright 2019, American Chemical Society.…”

Boron nitride nanotubes enhance mechanical properties of fibers from nanotube/polyvinyl alcohol dispersions

“…12,[20][21][22] Particularly, signicant improvement in thermal conductivity was obtained for BNNT-based composites prepared by vacuum ltration of aqueous dispersions of nanotube/polymer mixtures. [22][23][24] However, ber spinning and mechanical property enhancement of BNNT assemblies remain to be challenging.…”