Division of Advanced Materials , Korea Research Institute of Chemical Technology , Daejeon 34114 , Republic of Korea.
Department of Chemical and Biomolecular Engineering , Yonsei University , Seoul 03722 , Republic of Korea.
ACS Appl Mater Interfaces. 2018 Oct 10;10(40):34625-34633. doi: 10.1021/acsami.8b12075. Epub 2018 Sep 26.
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.
控制具有各向异性热传递特性的二维材料是解决未来电子设备中严重热问题的一种可行方法。我们展示了在包含少量（低于 10wt%）六方氮化硼（h-BN）纳米片的可拉伸聚乙烯醇（PVA）纳米杂化薄膜中，平面内热导率的显著增强。通过超声处理，将 h-BN 纳米片均匀分散在 PVA 聚合物溶液中，而无需进行额外的表面改性。该混合物用于制备导热纳米复合材料薄膜。当应变从 0 增加到 100%时，所得 PVA/h-BN 纳米复合材料薄膜的面内热导率增加到 6.4W/mK。更具体地说，与原始 PVA 相比，填充 10wt%填料的 PVA/h-BN 复合材料的热导率可以提高 32 倍。这种出色的热导率值明显大于目前用于平面热管理系统的材料。这一结果归因于在拉伸过程中 h-BN 颗粒在 PVA 链基体中的各向异性排列，增强了声子导电路径，从而提高了 PVA/h-BN 纳米复合材料的热导率和热性能。这些聚合物纳米复合材料的成本较低，因为昂贵的导电填料的用量减少了，并且它们可以作为高性能材料，用于未来的电子和电气设备的热管理系统，如散热器和热界面材料。
