Core–Shell Structured Biopolymer@BaTiO3 Nanoparticles for Biopolymer Nanocomposites with Significantly Enhanced Dielectric Properties and Energy Storage Capability

Flexible high-dielectric-constant (high-κ) nanocomposite dielectrics comprising polymer matrix and ceramic nanoparticles have important applications in the fields of electrical insulation and energy storage. However, most of the flexible high-κ nanocomposites are fabricated by using nonbiodegradable polymers as matrixes, which may not meet the increasing demands of society for environmental sustainability. In this study, using biodegradable polylactic acid (PLA) as a matrix and core–shell structured BaTiO3 (BT) nanoparticles as high-κ filler, we report the preparation and structure–property relationship of environmentally friendly flexible high-κ polymer nanocomposites. Two types of core–shell structured high-κ nanoparticles [polydopamine-encapsulated BT (BT@PDA) and PLA-encapsulated BT@PDA (BT@PDA@PLA)] as well as as-prepared BT nanoparticles were used as filler of the PLA-based high-κ nanocomposites. It was found that, compared with the as-prepared BT nanocomposites, the core–shell nanoparticle-based composites show enhanced dielectric constant, suppressed dielectric loss tangent, and enhanced breakdown strength. In addition, the BT@PDA@PLA nanocomposites have much higher dielectric constant and energy density. The nanoparticle–PLA compatibility and its influence on the dielectric and energy storage properties of the nanocomposites were also investigated. Because the polymer matrix is environmentally friendly and the preparation process of the core–shell nanoparticles is facile and nontoxic, the nanocomposites reported here may be used in the next generation of environmentally friendly high-performance energy storage devices.