NATURE-EID has proudly achieved important objectives. Regarding the scientific tasks involved in the project:
- Bio-sourced monomeric synthons have been identified as key materials focusing on biobased diols and dicarboxylic acids like 1,3-propanediol (All ESRs), 1,4-butanediol (ESR 3 and 4), maleic acid (ESR 2) or lactic acid (ESR 1). Some bio-sourced molecules, such as taurine or nicotinic acid have been also explored as organocatalysts (ESR 1, 2 and 3).
- Bio-sourced compounds, including terpenes and thiol-based structures, have been investigated for additive manufacturing applications (ESR 2). Organocatalysts have been priorly used for the synthesis including organics bases (ESR 1, 2 and 4) as well as acid:base catalysts (ESRs 1, 3 and 4) and bio-sourced molecules (ESR 2) yielding moderate to excellent yields. Special care was taken by all ESRs in developing the most benign synthesis possible, in the limit of the required reactivity and yield. ESR 1 was focused on obtaining block copolymers based on PLLA and bio-based polyethers using organic catalysts while ESR 2 obtained fully bio-sourced polyester resins under solvent-free conditions. Finally, ESR 3 and ESR 4 used bio-sourced molecules for the synthesis of the macrolactones and organic catalysts for their subsequent ring opening although it was demonstrated that metallic catalysts were more efficient in these specific cases.
- All the materials synthesised in this project have undergone physico-chemical characterisation and analysed for packaging applications. Notably, the thermal properties (DSC and TGA) (all ESRs), the processing properties, such as curing or 3D printing (ESRs 2 and 4) but also the mechanical properties such as tensile strength, elongation at break and viscosity (ESRs 2, 3 and 4), and the barrier properties towards CO2 and O2 (ESR1, 3 and 4). Although the materials prepared are not all reaching the ideal packaging properties, most of the polymers have demonstrated interesting properties: good processability in printing for the polyesters (Claire Morand, ESR 2), high molecular weights and good mechanical and barrier properties for PES (Bige Bati, ESR 4), interesting crystalline behaviour for the triblock based on PLLA and polyether (Flore Kilens, ESR 1), unique thermal properties for the PHAs with etheric bonds (Gabriella Garbonova, ESR 3).
- Finally, in this project, the end-of-life of the different materials was studied. It was demonstrated the feasibility of depolymerising different polymers such as the poly(ethylene succinate) (PES) into cyclic oligomers (ESR 4), and the poly(hydroxy acid) (PHA) into small molecules (ESR 1) which represent for both families of material a crucial step towards chemical recycling. Through hydrolysis biodegradation tests, we demonstrated that polymers synthesised in this project were biodegradable with up to 80% of mass loss after 70 days, notably PES of high molecular weight (ESR 4) and PLLA-based block copolymers (ESR 1).
Considering the management of the project and the different workshops and dissemination activities included in the formation:
- Four talented ESRs have been recruited and they have been enrolled in their respective doctoral programs at the university of the Basque Country (UPV-EHU) (Spain) and the University of Birmingham (UK).
- Three workshops as well as one summer school and one final conference were oragnised on various topics, i.e. Workshop 1: Sustainable packaging materials, Workshop 2: Life cycle assessment, Workshop 3: Oral Communication skills, Summer school: Recycling of plastics + training on IP for R&D, Final conference: "Is a circular economy for plastics possible".
- Virtual meetings with all ESRs and ERs are also regularly organised, every two months, to ensure a tight follow-up of the project.
- ESRs have been encouraged to participate in different outreach activities, and some have participated in different events including science open days, days of the women in science, the realisation of a project video targeted at students focused on the importance of recycling.
