Manipulating Interfacial Structures in PP/PMMA/PP-g-MAH Blends Toward High-Performance Capacitive Energy Storage

Polypropylene (PP) is extensively implemented in electronic equipment and power systems owing to its superior performance, such as high breakdown strength ( E b ), low dielectric loss (tan δ ), and outstanding self-healing capability. However, its low dielectric constant ( ε r ) and restricted energy density ( U e ) obstruct the miniaturization and integration of dielectric capacitors. To address these limitations, PP/PMMA/PP-g-MAH dielectric blend films were prepared via the melt blending and hot-pressing process. The transesterification reaction between the pendant anhydride groups of PP-g-MAH and the ester groups of PMMA forms ester bonds, which reduces the interfacial free energy and, in turn, significantly improves the compatibility between PP and PMMA. The blend film containing 4 wt% PP-g-MAH exhibits a high U e of 7.53 J/cm 3 at 502 MV/m, with an excellent charge–discharge efficiency ( η ) of 97.8%. This work presents a feasible strategy for developing all-organic polypropylene-based dielectric film with superior energy storage performance.