One-step assembly of poly(vinyl alcohol)/tannic acid complexes as a high oxygen barrier coating for poly(lactic acid) packaging films

The low oxygen barrier property of poly(lactic acid) (PLA) film extremely impedes its widespread application for food package. Appling an oxygen barrier coating to the surface of PLA film represents an effective means of addressing this issue. However, existing coating strategies via layer-by-layer are often time-consuming. Herein, we report the design and fabrication of a one-step scalable assembled poly(vinyl alcohol) (PVA)/tannic acid (TA) complex coating on the surface of PLA film as an advancement of our previous layer-by-layer assembled PVA/TA multilayer coating. By tailoring the mass ratio of PVA and TA, the oxygen barrier property of PLA film can be improved from low grade to high grade, which is comparable to that of PVA/TA multilayer coating (20 bilayers), and even superior to those of many food packaging films. Meanwhile, the oxygen barrier mechanism is analyzed, which proposes a new guideline for the development of high oxygen barrier coatings via a convenient and efficient approach.