Thermosetting materials from eugenol derivatives

Green chemistry explores safer ways to prepare new materials from renewable resources. Thermosets are generally prepared from a mixture of monomers, with at least one of them having three or more reactive functions. This allows the formation of a covalent three-dimensional network that gives the material some characteristics such as infusibility and insolubility, which are necessary for many applications such as coatings, adhesives, structural compounds, etc. Thermosetting materials are widely used in sectors of the electrical and electronics industry, in aeronautics and in construction, among others. If we consider biomass resources, eugenol is highly attractive as a raw material since it is easy to obtain and has a great natural abundance, which reduces its cost. It has a versatile structure that allows its easy modification to reach the convenient functionality for the preparation of the polymer network through various procedures. The structure of eugenol is quite rigid and compact, with a phenolic group and an allyl group that can later be transformed, and its structure allows a dimerization that generates bis-eugenol. Many researchers have started from eugenol to prepare adhesives by thiol-ene reactions or coatings by thiol-epoxy processes or even by homopolymerization of acrylic derivatives. Bisbenzoxazines or bismaleimides have also been prepared and polymerized, which have allowed obtaining a wide range of thermosetting materials. Finally, and even more important, eugenol can be used in food industry at low concentrations and, therefore, it is safe as a starting material for the preparation of green and non-toxic thermosets to be in contact with food or beverages. In the present chapter, a revision of the eugenol based thermosetting materials will be presented. This will include not only their preparation, but also some important characteristics and applications.