Layer-by-layer assembly deposition of graphene oxide on poly(lactic acid) films to improve the barrier properties

Layer-by-layer (LBL) assembly is an innovative method for fabrication of barrier layer structures on flexible polymers. In this work, two kinds of graphene oxide (GO) multilayer membranes with high barrier properties were prepared by applying LBL on poly(lactic acid) (PLA) films. Nanometer-scale GO multilayer membranes were coated on PLA films and their barrier properties were studied via water vapor and oxygen permeabilities. It turns out that a multilayer (polyethyleneimine (PEI)/GO)n PLA film has excellent oxygen barrier properties, and the oxygen permeability of a four-layer PEI/GO deposition is only 0.98% of the pure PLA film, with unsatisfied water vapor barrier properties. Using PEI/hexadecyltrimethylammonium bromide (CTAB)-modified GO assembling layers on the PLA substrate increased the water contact angle of the multilayer PLA film, and water vapor permeability decreased to 59.25% of the pure PLA film. GO nanosheets with better hydrophobicity can be obtained after being modified by CTAB at the same time, at the expense of partial oxygen barrier properties and transparency. This approach provides a new way to develop multilayer membranes with enhanced barrier performance of PLA films and shows significant interest in packaging applications.