Molecular Engineering of DAP Grafted Polypropylene for Ultrahigh‐Energy‐Density Film Capacitors and Smart Electrostatic Adhesion

Abstract Polymer dielectric films are widely used in capacitors due to their low cost, light weight, and compliance characteristics. However, their low energy density and the technological bottlenecks associated with forming ultra‐thin films over large areas severely limit further improvements in the performance of related devices and the expansion of their applications. a molecularly engineered dielectric material is developed by grafting diallyl phthalate (DAP) onto polypropylene via aqueous‐phase grafting technology. The conjugated benzene ring and polar ester group in DAP form deep level traps and a cross‐linked network, inhibiting the migration of space charges. The optimal modified film achieves a breakthrough strength of 853 MV m −1 and an elevated energy density of 12.90 J cm −3 (62.47% enhancement vs pristine PP), with 92.96% efficiency. Remarkably, it maintains 7.23 J cm −3 energy density at 105 °C. Furthermore, this material enables electrostatic clutches with 7.61 N cm −2 shear stress, capable of securing 2‐kg payloads and actuating robotic grasping. This work establishes a materials design paradigm merging high energy density capacitors with electrostatic adhesion smart devices.