Likhi Farzana Hasan, Singh Maninderjeet, Potdukhe Hitesh Ravi, Ajayan Pulickel M, Rahman Muhammad M, Karim Alamgir
Materials Science and Engineering, University of Houston, Houston, Texas 77004, United States.
Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77004, United States.
ACS Appl Mater Interfaces. 2024 Oct 23;16(42):57253-57267. doi: 10.1021/acsami.4c16329. Epub 2024 Oct 12.
Polymer nanocomposites hold great potential as dielectrics for energy storage devices and flexible electronics. The structural architecture of the nanofillers is expected to play a crucial role in the fundamental mechanisms governing the electrical breakdown and dielectric properties of the nanocomposites. However, the effect of nanofiller structure and dimensionality on these properties has not been studied thoroughly to date. This study explores the critical relationship between nanofiller dimensionality and dielectric properties in polymer nanocomposites. We fabricated polyvinylidene fluoride (PVDF) nanocomposites by incorporating a range of carbon-based nanofillers separately, including zero-dimensional (0D) carbon black (CB), one-dimensional (1D) multiwalled carbon nanotubes (MWCNT), 1D single-walled carbon nanotubes (SWCNT), two-dimensional (2D) reduced graphene oxide (rGO), and three-dimensional (3D) graphite. The frequency-dependent (1 kHz to 1 MHz) dielectric permittivity () of the nanocomposites at the same concentration of nanofillers demonstrated a hierarchical order, with MWCNT showing the highest permittivity (∼400%), succeeded by rGO (∼360%), CB (∼290%), SWCNT (∼230%), and graphite (∼70%), respectively. The temperature-dependent (50-150 °C) dielectric spectroscopy revealed high with increasing temperature due to the enhanced dipole movement. However, their dielectric breakdown strength and energy densities were not correlated to and exhibited the following order: SWCNT > MWCNT > CB > rGO > graphite. As the electrical breakdown depends upon the nanocomposites' mechanical strength, we correlated the mechanical properties with the nanofiller dimensionality, and Young's modulus followed the 1D ≈ 2D > 0D > 3D order. These findings will provide fundamental insights into designing tunable, conducive nanofiller-based nanocomposites in next-generation flexible electronics and capacitive energy storage devices.
聚合物纳米复合材料作为储能设备和柔性电子器件的电介质具有巨大潜力。纳米填料的结构体系预计在控制纳米复合材料电击穿和介电性能的基本机制中起关键作用。然而，迄今为止，纳米填料结构和维度对这些性能的影响尚未得到充分研究。本研究探讨了聚合物纳米复合材料中纳米填料维度与介电性能之间的关键关系。我们通过分别加入一系列碳基纳米填料制备了聚偏二氟乙烯（PVDF）纳米复合材料，包括零维（0D）炭黑（CB）、一维（1D）多壁碳纳米管（MWCNT）、1D单壁碳纳米管（SWCNT）、二维（2D）还原氧化石墨烯（rGO）和三维（3D）石墨。在相同纳米填料浓度下，纳米复合材料的频率依赖性（1 kHz至1 MHz）介电常数（）呈现出分级顺序，MWCNT的介电常数最高（约400%），其次是rGO（约360%）、CB（约290%）、SWCNT（约230%）和石墨（约70%）。温度依赖性（50 - 150°C）介电谱显示，由于偶极运动增强，随着温度升高介电常数增大。然而，它们的介电击穿强度和能量密度与介电常数无关，呈现以下顺序：SWCNT > MWCNT > CB > rGO > 石墨。由于电击穿取决于纳米复合材料的机械强度，我们将机械性能与纳米填料维度相关联，杨氏模量遵循1D ≈ 2D > 0D > 3D顺序。这些发现将为设计下一代柔性电子器件和电容式储能设备中可调谐、导电的基于纳米填料的纳米复合材料提供基本见解。
