Abstract

Layer-by-layer deposition of a polycation and of a cheap polyphenol, tannic acid, allows to produce thin coatings having an antioxidant activity proportional to the amount of deposited polyphenol. This means that the used probe, 2,2-diphenyl-1-picrylhydrazyl (DPPH), is able to reach all tannic acid molecules present in the film whatever their location. However, when the tannic acid containing film is capped with a few nanometers thick capping layer made of poly (allylamine hydrochloride) and poly (sodium 4-styrene sulfonate), the DPPH has no access anymore to the embedded tannic acid. On this basis, an application is proposed for the production of a packaging film containing tannic acid as a probe able to sense if the packaging has undergone some mechanical damage.

Keywords: Tannic acid; Layer-by-layer deposition; Antioxidant activity