Effects of the cross-linking structures of polyacrylate coating on PET films on oxygen permeability

Polyacrylate coating has been used for modifying Polyethylene terephthalate (PET) film to improve its oxygen barrier performance. However, comprehensive study on the oxygen barrier of polyacrylate coating is still underway. In this work, a series of polyacrylate coatings with different functional monomers such as maleic acid (MA), acrylic acid (AA), 2-hydroxyethyl acrylate (2-HEA), and 2-butene-1, 4-diol (1, 4-BED) were prepared by using Desmodur L75 (L75) and Erisys Ga240 (Ga240) as a curing agent. The polyacrylate coatings were characterized by Fourier Transform Infrared (FT-IR) spectrometer. The oxygen permeability (Po₂) of the coatings was measured by Gas Permeability Tester. The results reveal that anhydride moiety produced by dehydration of carboxylic acid is the key structure for enhancing the oxygen barrier property of the polyacrylate coating. Moreover, when the anhydride coexists with other cross-linking structures, the oxygen barrier performance of the resulting coatings was not further enhanced. Compared with the pristine PET substrate, the anhydride-containing polyacrylate-coated PET film has reduced Po₂ by 68%. This work provides a facile strategy for improving the oxygen barrier performance of PET film by coating amorphous polyacrylate.