Construction of particle network for ultrahigh permittivity of dielectric polymer composite toward energy devices: A molecular dynamics study

Energy storage and energy harvesting are the effective strategies to solve the energy and environmental crises. Dielectric polymer composites with high permittivity and energy density are extremely desired for the energy devices. However, there is a great deviation of effective permittivity between the real polymer composite and the ideal model, limiting their applications. In the present work, we adopt the coarse-grained molecular dynamics simulations to study the construction of particle network and the structure-property relationship, aiming to design polymer composite with high effective permittivity at low particle loading. Based on the analysis of topological structure of particle network, we propose three strategies, including grafting polymer chains to particles, selective locating into diblock copolymer and tuning moderate particle-matrix interaction. In particular, if the matrix chains are directly grafted to the particles, the network forms at very low particle loading, i.e., very low percolation threshold is achieved. Constructing the particle network opens a new way to design high permittivity of dielectric polymer composite, which is essential for their practical applications such as dielectric capacitors and triboelectric nanogenerators.