Self-healable capacitors with improved thermostability from stereocomplex PLA

Abstract

This study presents the development of sustainable, thermostable, and self-healable capacitors using poly(lactic acid) (PLA) as a bio-based dielectric. Stereocomplexation between high-molecular-weight poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) was employed to form stereocomplex PLA (scPLA), increasing the melting temperature (T_m) from 175 °C (PLLA) to 220–230 °C (scPLA). Low-molecular-weight PLLA (∼30 kDa) and high-molecular-weight scPLA (>100 kDa) were synthesized via ring-opening polymerization and blended in varying ratios to exploit dual melting transitions and tailor thermal properties. The resulting hybrid PLA networks, comprising mobile PLLA within a rigid scPLA matrix, were processed into capacitors by layer-by-layer printing. These devices exhibited self-healing behavior and maintained dielectric performance after thermal cycling and electrical breakdown. Notably, the PLA-based capacitors operated at temperatures up to 190 °C—approximately 90 °C higher than commercial biaxially oriented polypropylene (BOPP) capacitors—demonstrating significantly enhanced thermal stability and extended service life.