Anti-/Pro-Oxidant Behavior of Naturally Occurring Molecules in Polymers and Biopolymers: A Brief Review

Polymers and biopolymers are continuously subjected to the action of different stress factors, such as oxygen, heat, UV light, mechanical stress, humidity, etc., during their processing and service life, undergoing overall oxidative degradation, that causes performance and property deterioration. To improve the resistance at high temperatures and long-term weatherability of the polymers and biopolymers, usually, during their manufacturing, synthetic antioxidants and UV-light stabilizers are added. In the past decade, several concerns related to the impact of the synthetic stabilizers have emerged, and to reduce their negative effect on human health and the environment, their replacement with naturally occurring molecules, having similar protection abilities, is greatly welcome. It has been demonstrated that several natural polyphenols, vitamins, and carotenoids are efficient and suitable stabilizers for the protection of polymers and biopolymers from oxidative degradation. Besides, it is worth noting that some natural compounds exhibit concentrationdependent anti-/pro-oxidant activity in biopolymers and polymers, for the rational control of the additive contents. In this perspective, we briefly analyze the current results related to innovation in considering natural molecules for polymer and biopolymer protection or pro-oxidation, having potential industrial applications, pointing out some advantages, e.g. protection actions, and drawbacks, e.g. pro-oxidant and/or plasticizing actions, of these approaches.