Insight into the anti-aging mechanisms of natural phenolic antioxidants in natural rubber composites using a screening strategy based on molecular simulation

The failure of materials upon aging has led to the accumulation of waste and environmental pollution. Adding antioxidants (AOs) to the composites is one of the most effective ways to retard aging. However, traditional synthetic AOs are always detrimental to the environment and human health. The selection of antioxidants from streams by experiments will also definitely cost a lot of time and money. In addition, the complexity of thermo-oxidative aging factors along with the lack of quantitative tools significantly hampers its applications. So, building a screening strategy to quickly and easily find an appropriate and eco-friendly AO is imperative. In this study, we chose natural rubber (NR) as a matrix and provided a screening strategy based on diverse natural phenolic antioxidants to evaluate their ability in protecting NR composites. Thymol, α-tocopherol, and lipid-soluble epigallocatechin gallate (lsEGCG) were chosen from 18 natural phenolic antioxidants as potential alternative candidates. They were proved, indeed, to enhance the oxidative time in NR from experiments. Our results emphasized that thymol, α-tocopherol, and lsEGCG were promising alternatives for AOs in NR, and the in vitro toxicity test suggested that they are biocompatible. This study may develop a new strategy preference for screening the antioxidants by combining molecular simulation with the validation of experimental approaches, and therefore guide the AO molecular design with a more accurate theoretical prediction.