In-situ Liquid Exfoliation of Montmorillonite Nanosheets in Poly(lactic acid)to Resist Oxygen Permeation

As one of the most representative bioplastics,poly(lactic acid)(PLA) has been identified as an ecofriendly candidate for packaging medicine and food,holding distinct advantages of high strength and good biocompatibility. The application prospects,however,are largely dwarfed by the poor ductility and low resistance to gas permeation. In this work,the high-shear liquid exfoliation method was proposed to effectively transform the montmorillonite(MMT)to few-layer MMT nanosheets(MNSs),which thereby enabled in situ incorporation into the PLA matrix. Using a facile blade coating method,the fully biodegradable PLA nanocomposite films were prepared, with the MNS content ranging from 2% to 5% and 10%. The MNSs were found to be well exfoliated with a planar distance up to 3.11 nm,as accompanied by good alignment and strong interfacial adhesion within the composite films. These structural features conferred remarkable improvements in the mechanical properties and gas barrier performance for the composite films. This effort is of important significance for effective exfoliation of two-dimensional (2D)nanosheets,as well as fabrication of strong and high-barrier biodegradable nanocomposites.