Chemo-Mechanically Exfoliated Boron Nitride Nanosheet/Poly(Vinyl Alcohol) Composites as Efficient Heat Dissipation Components

Abstract

Advanced heat dissipation materials are necessary for powerful and miniaturized electronics. Hexagonal boron nitride (h-BN) is an ideal material for thermal management due to its electrical insulation but thermal conductivity. However, its utilization is seriously restricted by the pulverulence, and multilayer and chemical inertness. Herein, highly functionalized BN nanosheets (BNNSs) are exfoliated by a boric acid-assisted chemo-mechanical method and show stable dispersion in various solvents. An ingenious chemical etch-and mechanical forceinduced exfoliation and functionalization mechanism is proposed. Due to the existence of strong interfacial interaction between BNNSs and poly(vinyl alcohol) (PVA), a series of composite films with excellent thermal stability, low dielectric constant (2−4), negligible dissipation factor (<0.2), good machinability, and flexible bending and folding performances are prepared. The BNNSs' filling content can reach ∼90 wt %, and the BNNSs/PVA films' maximum tensile strength and modulus can be as high as ∼85.5 MPa and ∼7.6 GPa, respectively. Importantly, their in-plane thermal conductivity increases monotonously with the elevated BNNS content and temperature. The maximum thermal conductivity can reach up to 27.3 and 39.3 W•m −1 •K −1 at 25 and 100 °C, respectively. Noteworthily, the BNNSs/ PVA films show rapid thermal diffusion and can be readily designed as efficient heat dissipation components for integrated and intelligent electronic devices.

Highly Multifunctional Performances of Boron Nitride Nanosheets/Polydimethylsiloxane Composite Foams

“…The boric acid functionalized boron nitride nanosheets (BA-BNNSs) were prepared according to our previous report . First, via ultrasonic dispersion for 30 min, the BA-BNNS powders were uniformly dispersed in ethanol to obtain a BNNSs-ethanol dispersion solution.…”

“…The boric acid functionalized boron nitride nanosheets (BA-BNNSs) were prepared according to our previous report. 10 First, via ultrasonic dispersion for 30 min, the BA-BNNS powders were uniformly dispersed in ethanol to obtain a BNNSs-ethanol dispersion solution. Second, a proper amount of polydimethylsiloxane monomer (PDMS, SYLGARD 184, silicone elastomer base, Festering International Trading Co., Ltd.) and an appropriate amount of water were poured into the above-made BNNSs-ethanol solution, respectively, to form a pre-cross-linking precursor of BNNSs-PDMS emulsion after stirring for 15 min at room temperature.…”

Enhanced Anti‐Corrosion Performance of Carbon Steels via CeO2@BNNSs/Epoxy Resin Composite Coatings

“…The highly dispersed CeO 2 @BNNSs composites were synthesized through a three‐step method, as shown in Figure . First, the highly‐multifunctional BNNSs powders were prepared by the boric acid (BA)‐assisted chemo‐mechanical method reported previously by us, [ 46 ] which have abundant highly‐functionalized OH, NH 2 , and BA groups onto their edges and (0002) plane surfaces. A coating layer of PDA was bonded onto the surfaces of BNNSs due to the strong reaction function of the surficial NH 2 groups and PDA molecules in a weak base environment, [ 36 ] to make the PDA‐BNNSs.…”

Enhanced Performance of Li–S Batteries due to Synergistic Adsorption and Catalysis Activity within a Separation Coating Made of Hybridized BNNSs/N-Doping Porous Carbon Fibers

“…Due to the nonmelting transition of PAN at high temperature, the carbonization of BNNSs/PAN-MCA fibers can ensure the final C-fiber connectivity without breaking during the pore-forming process of MCA's in situ gasification. 29 Because our highly functionalized BNNS (Figure S1 in the Supporting Information) powder was highly dispersed in most of the organic solvents, 30 S6 in the Supporting Information).…”

“…Due to the nonmelting transition of PAN at high temperature, the carbonization of BNNSs/PAN-MCA fibers can ensure the final C-fiber connectivity without breaking during the pore-forming process of MCA's in situ gasification. 29 Because our highly functionalized BNNS (Figure S1 in the Supporting Information) powder was highly dispersed in most of the organic solvents, 30 a uniform embedding of the BNNSs was easily achieved from the initial fibrous precursor to the final carbonized C fibers. This can be confirmed by the uniform B, C, and N elemental mappings (Figure S2 in the Supporting Information).…”