Epoxidation and Curing of Bio-Renewable para-Coumaric Acid

Epoxy resin is a thermoset polymer made from epoxy monomers combined with a curing agent. It is commonly used for products that require rigidness and durability, however, once they are no longer usable, they accumulate in landfill waste as they are not biodegradable due to their production from crude oil and thus are highly resistant to breaking down in the environment. Therefore, it is of interest to replace nonrenewable starting materials such as petroleum with a renewable feedstock. One such substance from which epoxy monomers can be derived from is lignin, a complex monomer found in the cell wall of plants that is often a waste by-product in the paper industry as it weakens the paper. Under the right conditions, lignin can be depolymerized into a mixture of small molecules that have rigid aromatic rings, making them a promising starting material for synthesizing epoxy resins. This project focused on a small molecule of the complex lignin structure called para-coumaric acid which was epoxidized and the new structure was characterized. This was done using a two-step synthesis where, first, the para-coumaric acid was allylated using allyl bromide. Once the allylated compound was verified using NMR, the double bond in the allylated coumaric acid was epoxidized with meta-chloroperoxy benzoic acid to get epoxy groups. NMR was once again used to characterize the new epoxidized para-coumaric acid. This novel monomer was then cured with an anhydride curing agent to create epoxy resin which was then tested to find its thermal properties.