Prof. Angels Serra

Title: Bio-derived epoxy vitrimers designed to maximize recyclability, reshapeability, and adhesion.

Thermosetting materials are prized for their remarkable mechanical and thermal properties, owing to their three-dimensional covalent structure. This structural characteristic makes them indispensable in various applications such as adhesives, coatings, composites, aerospace, and electronics. However, a notable drawback of thermosetting materials is their irreversible cross-linked structure, preventing reforming or recycling after curing. To mitigate this limitation, the incorporation of dynamic covalent bonds has been introduced, leading to the creation of covalent adaptable networks (CANs) or vitrimers.

Several reversible exchange reactions have been documented for vitrimer preparation, including transesterification, transamination, disulfide exchange, siloxane equilibrium, amine-urea exchange, and transthiocarbamoylation.

While certain reactions require catalysts such as transesterification or transthio-carbamoylation, others, like those involving imine and disulfide groups, do not. Imine and disulfide groups are currently gaining great interest due to their short stress relaxation times and the ease with which they can be mechanically and chemically recycled.

Another consideration lies in the sustainability of the raw materials employed in the thermosets production. Adhering to the principles of green chemistry entails avoiding fossil-based feedstock and opting for those obtainable through sustainable means. Presently, a wide range of compounds can be sourced from renewable resources like vegetable oils and carbohydrates. Lignin can be extracted from agricultural and forestry residues, and from it, various valuable compounds can be obtained, as vanillin or eugenol.

Epoxy thermosets represent a prominent category among these types of materials. They are derived from epoxy monomers capable of reacting with amines, thiols, or anhydrides as curing agents, resulting in materials exhibiting excellent adhesive properties and robust thermal and chemical stability. Incorporating exchangeable groups into either the monomer or the curing agent structure can enable the development of thermosetting adhesives that are recyclable and capable of being reshaped. This communication will explore the impact of imine and disulfide groups in epoxy thermosets and highlight their associated advantages.

Prof. Angels Serra got a PhD in Chemical Sciences from the University of Barcelona, in 1985 respectively. She obtained the position of Associate Professor in 1987 and is Full Professor since 2000. She was awarded as Distinguished Professor by the URV in 2017. Her research focuses primarily on improving thermosetting materials and their curing processes. She has contributed to the development of new initiators and sequential two-stage curing procedures, as well as the implementation of new latent systems to control curing and facilitate complex manufacturing processes. She has experience in epoxy materials, thermosets obtained through click methodologies, and thermosets with improved characteristics obtained through copolymerization of different monomers or through the addition of stars and hyperbranched polymers. Recently, her interest has focused on reprocessable thermoset materials by introducing exchangeable groups into the network. Her research translates into more than 250 ISI articles, 5 book chapters, 3 patents, and a large number of contributions to congresses and conferences. She has been very active in collaborating with industries and serves on the editorial board of the journals Polymers and Reactive and Functional Polymers.