Synthesis and Properties of Furan Derivatives for Epoxy Resins

The discovery of huge petroleum reserves in the 19th century was a golden opportunity that promoted the industrial revolution, by offering a wide variety of cheap raw materials and a reliable source of energy. This caused an unprecedented increase of commodity and production of specialty chemicals in order to fulfill the needs of the global markets. However, as global warming and environmental issues have become a hazardous and worried situation, researchers are looking for biorenewable monomers with low toxicity in order to produce more sustainable polymers. This policy was applied to epoxy resin materials because of their high volume production in industry for a wide range of applications. This review highlights the recent advances in the preparation of diamines and diepoxy monomers for the synthesis of epoxy resins, mainly from 2-furfural, 5-(hydroxymethyl)furfural (5-HMF), and 2,5-furandicarboxylic acid (FDCA), obtained from natural cellulose and hemicellulose feedstocks, respectively, and able to replace phthalic moieties in polyethylene terephthalate. In addition, the processes involved in the monomer preparations, such as reductive amination, etherification, esterification, and carbonatation, are listed. This review, reporting quasi-exhaustive synthetic pathways of epoxy precursors containing furanic moieties and describing the resulting resins, is composed of seven main parts, based on the synthesis of glycidyl derivatives containing one or two or four furan nuclei bearing or not a spacer between the furan ring and the function. The influence of the substituents on furan moieties (O, CO, CH2) and the spacer between these groups have also been evaluated. Finally, thermal and a few mechanical properties of the obtained biosourced epoxy resins were compared to their fossil fuel analogues (from bisphenol A), featuring the high potential of biobased monomers as substituents for nonrenewable ones.