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

Abstract 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.