Synthesis and Characterization of Functionalized Fe₃O₄/Boron Nitride as Magnetically Alignable 2D-Nanofiller to Improve the Thermal Conductivity of Epoxy Nanocomposites

Abstract

In the electronic industry, there is an enormous request for high thermal conductivity polymer. In this regard, we propose a novel synthesis route to produce magnetically alignable 2D-nanofiller. In our work, surface modification of boron nitride nanosheets (BNNs) with polyacrylamide brushes are explored. For this purpose, the postpolymerization reaction of BNNs is followed by the redox polymerization of acrylamide onto the surfaces of already hydroxyl-functionalized BNNs. Afterward, magnetic iron oxide nanoparticles are contributed to modified BNNs through polyacrylamide chelating effect. Finally, to provide high thermal conductive and magnetic responsive nanocomposites, the functionalized Fe 3 O 4 /BNNs are dispersed in epoxy matrix and aligned under an external magnetic field. According to the results of thermal conductivity studies, thermal transport of the nanocomposites increases to 0.37 W/mK by adding only 10% of functionalized Fe 3 O 4 /BNNs (at 25 °C). Mechanical and thermal properties of these nanocomposites are compared with the pristine epoxy polymer as a control sample.

Novel Poly(m‐phenyleneisophthalamide) Dielectric Composites with Enhanced Thermal Conductivity and Breakdown Strength Utilizing Functionalized Boron Nitride Nanosheets

“…However, the (100) peak of fBNNSs in all PMIA/fBNNSs composites are not apparent in Figure 6c, suggesting that fBNNSs platelets were almost oriented along the horizontal direction. [5] The horizontally oriented fBNNSs could generate more heat dissipation paths than vertical direction, and thus showing high anisotropic thermal conductivities in both directions.…”

“…Currently, introducing thermally conductive fillers into polymer matrix is a prevalent and practical approach to enhance thermal conduction of fabricated composite. There are sorts of thermally conductive fillers, including carbon‐based fillers (graphene, carbon nanotubes), metallic fillers (copper, aluminum), ceramic fillers (silicon carbide (SiC), hexagonal boron nitride (h‐BN), aluminum nitride (AlN)) . Though carbon‐based and metallic fillers own excellent thermal conductivities, their high electrical conductivities can impair intrinsic insulation property of polymer matrix, impeding the application of device in insulative areas .…”

Thermal Conductivity and Cure Kinetics of Epoxy-Boron Nitride Composites—A Review

“…First, the usually observed upward curvature in the dependence of the thermal conductivity on BN content is not displayed by the results of Yung and Liem [54], which are shown separately in Figure 8; instead, there appears to be a tendency to reach a limiting value as the BN content increases. Second, the results of Yung et al [151] Open circles refer to data from references [54,151], open squares refer to data from references [89,90,114,116,125,127,132,143,147,153,158]. The dashed trend lines indicate the overall tendency for the dependence of thermal conductivity on BN content (excluding the data represented by the open circles): an upper trend line, below which more than 95% of the values fall; and a lower trend line, below which fewer than 5% of the values fall.…”

“…These are the data which correspond to samples in which orientation of the BN particles has deliberately been introduced. The orientation can be induced by various means: gravity alignment and subsequent resin infiltration [147]; the application of high pressure to partially cured samples before the final cure [90,153,158]; spin-coating of films and hot pressing after pre-cure [116]; magnetic alignment of Fe 3 O 4 -decorated BN particles [114,125,127]; or by resin infiltration of hierarchically ordered 3-dimensional templates [89,132,143]. The orientation induced usually results in a highly anisotropic thermal conductivity.…”

“…Some other relatively recent results were also less successful. Salehirad et al [125] adopted the same magnetic alignment principle but used a slightly modified procedure in which 70 nm h-BN nanoparticles were first exfoliated into nanosheets by sonication, polyacrylamide was then grafted and the nanosheets were finally modified with Fe 3 O 4 nanoparticles. Epoxy composites with filler loadings up to 20 wt.% were cast in a mould located between two magnets, but the results were not definitive.…”