High strength and biodegradable dielectric film with synergistic alignment of chitosan nanofibrous networks and BNNSs

The development of biodegradable and robust dielectric capacitors with high breakdown strength and energy density are indispensable. Herein, the high strength chitosan/edge hydroxylated boron nitride nanosheets (BNNSs-OH) dielectric film was fabricated via combining the dual chemically-physically crosslinking and the drafting orientation strategy, which could induced BNNSs-OH and chitosan crosslinked network alignment within the film via covalent and hydrogen bonding interaction, leading to the comprehensive reinforcement of tensile strength from 126 to 240 MPa, the Eb from 448 to 584 MV m-1, the in-plane thermal conductivity from 1.46 to 5.95 W m-1 K-1 and energy storage density from 7.22 to 13.71 J cm-1, superior than the comprehensive evaluation of the reported polymer dielectrics. The dielectric film could be completely degraded in soil in 90 days, which opened a new path for the development of next-generation environment-friendly dielectrics with excellent mechanical and dielectric properties.