Poly(lactic acid) based Pearl Layer Moistureproof Membrane for Flexible Laminated Packaging

The development of bio-based polymer materials, such as polylactic acid (PLA) -based polymers, is an effective strategy to reduce dependence on petrochemical-based polymers. However, the preparation of bio-based polymers with high barrier properties is a major challenge. To overcome this challenge, a nacreous layer structure with a ' brick and mud ' pattern is mimicked to improve the overall performance of the material. In this paper, Poly (_L -lactic acid) (PLLA) and Polypropylene Glycol (PPG) was combined to prepare bio-based polyurethane (PU-PLLA), which is used as the slurry structure of nacreous layer. The bio-based biomimetic composite membrane (PU-PLLA/BN) is then obtained by adding boron nitride (BN, brick structure of pearl layer) to it. The water vapor permeability test results show that the permeability of PU-PLLA material can be reduced by more than 50% by 5 wt.% BN, which is because the addition of BN can increase the length and tortuosity of the gas molecular diffusion path in the composite. Therefore, this pearl-inspired PU-PLLA/BN film has excellent moisture resistance, which opens up a broad road for the practical application of PLLA in flexible laminated packaging.