Exploration of a gallic acid-based alternative to bisphenol A

Abstract

Epoxies are used in a wide variety of applications in plastics and composites due to their excellent material properties. These properties are attributed to the aromatic rings present in their structure. However, the source of these aromatic rings is bisphenol A, one of the compounds responsible for the deterioration of human health and the environment. Thus, there is a drive to replace bisphenol A with less hazardous substitutes in plastic production. This project aimed to synthesize an alternative to bisphenol A, inspired by its di-functional structure. The base material chosen was gallic acid, a naturally-derived phenolic acid from the tannins of plants. Two gallic acid molecules were linked by a di-functional bridge to mimic the structure of bisphenol A. This bridge can be customized to introduce tailor-made properties. The project assessed two routes for the synthesis of the bridge: a diol and a diamine. Through the evaluation of the routes, we chose to focus on the N,N’-dicyclohexylcarbodiimide (DCC) route as it had the most advantages. This route created the product, N,N'-(1,4-phenylene)bis(3,4,5-tris(oxiran-2-ylmethoxy)benzamide), Glycidyl Phenylene-Gallic Amide (GPDA). Synthesized products were then characterized through differential scanning calorimetry, thermal gravimetric analysis, Fourier transform infrared spectroscopy, and high-performance liquid chromatography. These provided insights to the outcome of the synthesis steps and evaluated the thermal properties of the GPDA resin.