The rapid expansion of electronics, particularly in IoT networks, aerospace, and electric vehicles, has created an urgent need for high-temperature, high-energy-density capacitors. A significant challenge in these systems is achieving homogeneous dispersion of high-k nanofillers within polymer matrices, as particle agglomeration leads to electrical losses and reduced performance. We have employed surface-initiated atom transfer radical polymerization (SI-ATRP) to achieve superior dispersion of nanoparticles within polymer-based capacitors. Our ongoing research focuses on core-shell nanocomposite dielectric materials which exhibit high breakdown strength, low conduction loss, and enhanced charge-storage capacity. These innovations hold promise for next-generation capacitors used in power electronics, pulsed energy storage, and extreme-temperature environments.