Light weight, low dielectric constant, super-robust polylactide film based on stress-induced cavitation aided by crystallization

Abstract

Exploiting pollution-free and highly efficient pore-forming method for low dielectric constant biodegradable materials remains a challenge in green electronics field. As biodegradable polylactide (PLA) exhibits good electric insulation, herein a facile “casting-thermal stretching” approach via stress-induced cavitation aided by crystallization is reported to obtain porous PLA films. The extensional stress and optical purity have vital influence on determining the hierarchical structures (oriented crystallites and porous structure). Hence the PLA with the highest optical purity (>99%) has the best comprehensive properties: When the DR reaches 6.6 (PLA99–6.6), the PLA99–6.6 film exhibits light weight (0.99 g/cm3), low dielectric constant (2.48 at 1 kHz), low dielectric loss (4.6 × 10−3 at 1 kHz), super robustness (tensile strength of 185.9 MPa, Young's modulus of 4.5 GPa and tensile strain of 12.4%) and excellent durability under high temperature and humidity condition, which have great potential application in green electronics.