Organic-Inorganic Hybrid Coatings for the Modification of Barrier Properties of Poly(lactic acid) Films for Food Packaging Applications

Organic-inorganic hybrid coatings based on poly(epsilon-caprolactone), poly(ethylene oxide) or poly(lactic acid) as organic phase and silica from tetraethoxysilane as inorganic phase were prepared by the sol-gel approach. Coatings were applied onto poly(lactic acid) films for food packaging in order to improve its barrier properties towards oxygen and water vapour. All the prepared coatings were dense, homogeneous layers characterized by a good adhesion to the substrate. The permeance of the coating layers resulted one order of magnitude lower than that of the uncoated poly(lactic acid) (PLA) film. The hydrophilic character of the coating did not permit to gain a significant decrease in the water vapour permeance. The perfect visual transparency of the coatings allows their application without worsening of the esthetical properties of the substrate PLA film.