High-permittivity (high-k) materials play a key role in advanced electronics and electrical power systems. How to prepare the flexible material with high permittivity and low dielectric loss turns out to be a hard work due to the essential low permittivity of polymers. In this work, a kind of ductile polymer-based composites was fabricated by incorporating ionic liquids into polymer matrices. The optimized permittivity of composite with 50 wt% ionic liquid reached up to 3.3 × 10⁴, while the dielectric loss was as low as 0.65. The temperature dependence of dielectric properties was also investigated, and a high permittivity as well as low dielectric loss at 100 Hz of about 2.0 × 10⁴ and 0.23 were achieved at 80 °C, respectively. Furthermore, the study reveals that the dielectric loss peaks of the composite films can be affected by the content of ionic liquid, temperature even the size of ions. In short, the finding indicates that the addition of ionic liquids into polymers provides a big opportunity to improve dielectric properties of polymer materials.

高介电常数（high- k）材料在先进的电子和电力系统中起着关键作用。由于聚合物的介电常数很低，因此如何制备具有高介电常数和低介电损耗的柔性材料是一项艰巨的工作。在这项工作中，通过将离子液体掺入聚合物基体中，制造了一种可延展的聚合物基复合材料。50％离子液体的复合材料的最佳介电常数达到3.3×10 ⁴，而介电损耗低至0.65。还研究了介电性能的温度依赖性，并且在100 Hz时介电常数高且介电损耗低，约为2.0×10 ⁴在80°C时分别达到0.23和0.23。此外，研究表明，复合膜的介电损耗峰会受到离子液体含量，温度甚至离子尺寸的影响。简而言之，该发现表明将离子液体添加到聚合物中为改善聚合物材料的介电性能提供了很大的机会。