All-Organic Multilayer Coatings for Advanced Poly(lactic acid) Films with High Oxygen Barrier and Excellent Antifogging Properties

Poly(lactic acid) (PLA) has been increasingly employed as a promising packaging material. Unfortunately, PLA film suffers low oxygen barrier and poor antifogging issues, which extremely restrict its practical applications. Despite some progress, to date it remains a challenge to construct a biodegradable, transparent, highly oxygen-barriered and antifogging coating for the PLA film via a facile approach. Here, we report a facile construction of biodegradable and all-organic coating with high transparency via hydrogen-bonded layer-by-layer assembly of poly(vinyl alcohol) (PVA) and tannic acid (TA). With the presence of 20 bilayers of PVA and TA, the oxygen permeability is reduced to 0.52 × 10–16 cm3·cm/[cm2·s·Pa], approximately 450 times lower than that of PLA film. Moreover, fogging issue for PLA film can be effectively addressed only with five bilayers of PVA and TA. These improvements are attributed to the hydrogen-bonding interactions and polyphenol groups within the multilayer coating. This work may provide a facile strategy for the design of biodegradable and highly transparent coating for the high oxygen barrier and antifogging applications by using organic molecules as building blocks.