Antimicrobial and improved barrier properties of natural phenolic compound-coated polymeric films for active packaging applications

Functional antimicrobial low-density polyethylene (LDPE) films with coatings containing different amounts of pyrogallol (PGL), a natural phenolic substance, and polyurethane were prepared. To examine the applicability of the prepared LDPE/PGL films in packaging, the films were characterized by scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis, and X-ray diffraction. The role of the coating, the barrier and color properties, and the antimicrobial activity of the films were evaluated. The thermal stability of the LDPE/PGL films was affected by the PGL concentration. Coatings with pyrogallol caused the barrier properties for water, and oxygen was increased from 0.78–0.32 to 470 ± 23.2–273 ± 57.1 (g mm)/(m² h kPa), respectively. These findings indicate that the barrier properties of the LDPE/PGL films were highly improved compared to those of neat LDPE. Moreover, the LDPE/PGL films exhibited acceptable antimicrobial activity against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), especially for S. aureus. Further studies are necessary to increase the thermal stability of the pyrogallol coatings with the LDPE substrate in order to improve their performance and extend their packaging applications.