Self-Cleaning, Transparent, Anti-icing of Polylactic Acid Films with stiffness-toughness balance via stretching-nonsolvent induced phase separation-liquid infusion process

Abstract

Polylactic acid (PLA) is a highly sustainable and fully biodegradable polymer regarded as a promising alternative to conventional polyolefin films in packaging applications. Nevertheless, PLA inherently suffers from various bottlenecks such as brittle and hydrophilicity due to its ester-rich backbone, which leads to relatively narrow application area. Exploring its promising comprehensive performance should be valuable for expansion of applications. In this study, we develop a facile and green strategy of stretching-nonsolvent induced phase separation-liquid infusion (NIPS-liquid infusion) to fabricate PLA films integrating self-cleaning, high transparency, anti-icing, and stiffness-toughness balance. The NIPS process generates a porous crystalline morphology on the film surface, considerably improving surface roughness and hydrophobicity. Subsequently, hydrophobic liquid matching the refractive index of PLA has been injected, which not only restore the film's transparency (with a light transmittance of 90.9%) but also achieve outstanding lubricity and self-cleaning properties. The resulting material maintains self-cleaning capability and optical clarity under low-temperature conditions without significant loss of stiffness-toughness balance induced by stretching-induced orientation of amorphous phase. This work offers a practical route for designing multi-functional PLA-based packaging materials such as appliances used in refrigerator.