Liquid metal (LM) is a promising polymer filler because of its high dielectric properties and fracture flexibility. However, liquid metal is easy to agglomerate and unstable, which limits its application in silicone rubber (PDMS). In this work, a novel strategy to improve the stability of liquid metal and enhance its interfacial compatibility with silicone rubber was proposed by using core–shell silica-coated liquid metal nanoparticles (LM@SiO2–NH2) as a filler. When the filling amount is 40 wt%, the dielectric constant of the LM@SiO2–NH2/PDMS composite increases from 4.5 to 13.9, which is 340% of that of PDMS. The composite exhibits a dielectric loss of less than 0.008 at frequencies of 103–107 Hz. In addition, the mechanical properties of the composites are enhanced and the heat transfer performance and thermal stability show the best performance among the prepared composites.
