Anisotropy-Driven High Thermal Conductivity in Stretchable Poly(vinyl alcohol)/Hexagonal Boron Nitride Nanohybrid Films

Abstract

Controlling the anisotropy of two-dimensional materials with orientation-dependent heat transfer characteristics is a possible solution to resolve severe thermal issues in future electronic devices. We demonstrate a dramatic enhancement in the in-plane thermal conductivity of stretchable poly(vinyl alcohol) (PVA) nanohybrid films containing small amounts (below 10 wt %) of hexagonal boron nitride ( h-BN) nanoplatelets. The h-BN nanoplatelets were homogeneously dispersed in the PVA polymer solution by ultrasonication without additional surface modification. The mixture was used to prepare thermally conductive nanocomposite films. The in-plane thermal conductivity of the resulting PVA/ h-BN nanocomposite films increased to 6.4 W/mK when the strain was increased from 0 to 100% in the horizontal direction. More specifically, the thermal conductivity of a PVA/ h-BN composite film with 10 wt % filler loading can be improved by up to 32 times as compared to pristine PVA. This outstanding thermal conductivity value is significantly larger than that of materials currently used in in-plane thermal management systems. This result is attributed to the anisotropic alignment of h-BN particles in the PVA chain matrix during stretching, enhancing phonon conductive paths and hence improving the thermal conductivity and thermal properties of PVA/ h-BN nanocomposite films. These polymer nanocomposites have low cost as the amount of expensive conductive fillers is reduced and can be potentially used as high-performance materials for thermal management systems such as heat sink and thermal interface materials, for future electronic and electrical devices.

Deformable High Loading Liquid Metal Nanoparticles Composites for Thermal Energy Management

“…Polymer/fillers composites are promising heat dissipation materials for thermal management systems. For example, the thermally conductive fillers such as hexagonal boron nitride, [3,4] Cu nanowire, [5,6] Ag nanowire, [6,7] aluminum nitride, [8,9] carbon nanotubes, [10] and graphene [11] can be dispersed in polymer matrix, and the composites showed thermal conductivity of ≈8 W mK −1 . A higher loading amount of the filler improves the higher thermal conductivity, however, the stiffness of the composite also increased simultaneously.…”

High thermal conductivity of self‐healing polydimethylsiloxane elastomer composites by the orientation of boron nitride nano sheets

“…), 12,13 carbon fillers (graphite, graphene, 14,15 carbon nanotube (CNT), carbon black, carbon fiber, etc. ), ceramic fillers 16,17 (Al 2 O 3 , 18,19 SiC, 20,21 BN, 22–24 AlN, 25 etc.). Compared with the metal fillers and the carbon‐based fillers, the ceramic fillers have the advantages of low cost and good electrical insulation, 26 which makes them the optimum choice as the thermally conductive filler 27 …”

Highly Ordered BN⊥–BN⊥ Stacking Structure for Improved Thermally Conductive Polymer Composites

“…The formation of continuous thermally conducting paths by a controllable alignment of fillers inside composite is an effective method to improve the thermal conductivity of TIMs along a certain direction at low loading. Substantial efforts have been devoted to align the fillers, especially for anisotropic materials like BN into the composite using different strategies such as electrospinning, [16,17] stretching, [18] doctor blading [19] induced by magnetic field, [20][21][22] electric field, [23,24] gravitational force field, [25,26] and 3D printing technology. [27] Freeze-casting method is also a promising approach to form highly ordered structures of fillers inside the composite.…”