Renewable Zein-Induced Physical Networks in PVDF Composites for Hydrogen Bond-Mediated Crystallization Control and Ultrahigh Energy Storage Performance

This study presents a sustainable bio-composite strategy enhancing the dielectric energy storage performance of poly (vinylidene fluoride) (PVDF) through acetate-modified zein proteins. The amphiphilic structure of denatured zein, featuring exposed -OH, -NH 2 , C=O, and -COOH groups, enables multipoint hydrogen bonding with PVDF chains. These interactions achieve dual key effects: promoting β-phase crystallization in PVDF to significantly increase the dielectric constant by 40% without elevating dielectric loss, while simultaneously forming hydrogen bond-mediated physical crosslinking networks. This network not only homogenizes electric field distribution and suppresses space charge accumulation but, crucially, counteracts the potential increase in dipole relaxation losses associated with reduced crystallinity by effectively restricting polymer chain mobility. The optimized microstructure delivered exceptional electrical properties including high breakdown strength, an energy density of 11.31 J/cm 3 , and 83.44% energy efficiency at the maximum field, surpassing most reported PVDF composites. Unlike traditional inorganic fillers, this bio-derived modifier addresses crystalline limitations and interfacial defects while avoiding the brittleness associated with chemical crosslinking. This work fundamentally elucidates protein-polymer interfacial synergy and establishes a scalable, eco-friendly paradigm for high-performance dielectric composites, offering significant energy storage potential.