Periodic Reporting for period 1 - VIT (Polymer engineering via molecular design: embedding electrical and optical properties into VITrimers)
Reporting period: 2021-09-01 to 2024-02-29
Plastics are strategic materials for several key sectors and the rethinking of plastics within the circular economy concept is pivotal for a more sustainable and resource efficient Europe. In particular, composites and thermosets, materials of choice for applications where long-term use and mechanical resistance are critical, cannot be technically re-processed since at elevated temperature they do not flow but degrade. A powerful new strategy to produce reprocessable cross-linked polymers is the introduction in polymers of cross-links able to reverse or exchange at elevated temperatures. These materials are defined as covalent adaptable networks (CANs) or sometimes vitrimers. Their ability to shuffle chemical bonds through exchange reactions at high temperature allows for material reprocessing. To fully exploit the potential of vitrimers in high-end consumer goods, their properties need to be tailored to the specific applications by embedding functional monomers or additives. Moreover, to accomplish vitrimer circularization, such properties must also be preserved upon recycling. The VIT proposal intends to engineer vitrimers by endowing these polymers with highly desired functional optical and electrical properties, which are retained after recycling, fulfilling the circular economy paradigm “use-reuse-repair-recycle”. The project aims to foster cross-fertilization within polymer science by seconding ERs and ESRs across Europe and worldwide. To facilitate knowledge transfer, VIT integrates diverse expertise encompassing synthetic chemistry, polymer and material science, photochemistry, and polymer technology.
Different mechanophores, namely stress or strain activated molecular units that can be inserted into a polymeric material to provide optical evidence of local stress, were synthesized. PE-based vitrimers were produced using robust and extensively studied mechanophores as crosslinkers. The materials were fully characterized to prove reversibility of the optical response as well as their recyclability. Epoxy-vitrimers were embedded with nanoparticles containing reporting dyes. The nanocapsules were functionalized with carbon nanostructure to locally quench the dye once activated and to self-heal the polymeric matrix via local heating. Other related key activities included synthesizing and modifying epoxy vitrimers with chromophores to create self-healing films and coatings, developing materials with writing and erasing capabilities, and exploring the potential of chromophores for detecting microcracks in polymers. Water-sensitive dyes were embedded in polyolefins to explore the possibility of using these molecules to produce a humidity reporting PE-based vitrimers. The dispersion of these dyes in PE proved to be effective, maintaining fluorescence and color. Fluorescence spectra revealed the effect of humidity on the selected compound allowing for ratiometric measurement of humidity uptake. The insulating properties of PE-based reversible cross-linked polymers were analyzed and compared to the ones of crosslinked polyethylene (XLPE), the most widely used insulation material for extruded high-voltage power cables. The possibility to use reversible cross-linked ionomers as insulating materials was explored. PE-based ionomers were synthetized and their insulating properties resulted to be comparable to XLPE. Additionally, the ionomers exhibited relatively high thermal conductivity, comparable to or higher than XLPE.
Another aspect covered was the enhancement of Luminescent Solar Concentrators (LSCs) through the development of epoxy-based vitrimer materials. Coumarin-based dyes were incorporated into the epoxy vitrimers for their potential in LSC applications. Luminescent thin-films were successfully deposited onto glass slides via spin-coating deposition. The waveguiding abilities of these matrices were optimized, demonstrating efficient light propagation. Finally, we are exploring the possibility of using vitrimers for biosignals monitoring. Key findings included the potential of conductive polymers and exploring new materials for biosignals. During this first period, the VIT secondees were exposed to several materials characterization techniques, such as UV-Vis and NMR spectroscopy, SEM, DSC and DMTA, while training sessions and group meetings facilitated knowledge exchange and collaborations. They participated to international conferences, schools and industrial visits, fostering multidisciplinary collaboration and expanding research networks. A summer school was held in Wien. The school was accessible online for partners and secondees unable to attend in person. The school provided an excellent opportunity to bring together ESRs and ERs to share ideas and expertise and maximize knowledge sharing. The secondments resulted in promising outcomes, including publications and strengthened collaborations between institutions and industries. As regards DISSEMINATION, key aspects of the project were illustrated on the VIT website. The consortium has been very active in the communication of results to the scientific community. Up to now the number of publications in international scientific journal amounted to 3. All the papers published with acknowledgement to VIT have an open access, to maximize the dissemination of the results. Every dissemination action has been highlighted both on the social media and the website of the project, as well as on the ones of the involved groups and Institutions.
Another aspect covered was the enhancement of Luminescent Solar Concentrators (LSCs) through the development of epoxy-based vitrimer materials. Coumarin-based dyes were incorporated into the epoxy vitrimers for their potential in LSC applications. Luminescent thin-films were successfully deposited onto glass slides via spin-coating deposition. The waveguiding abilities of these matrices were optimized, demonstrating efficient light propagation. Finally, we are exploring the possibility of using vitrimers for biosignals monitoring. Key findings included the potential of conductive polymers and exploring new materials for biosignals. During this first period, the VIT secondees were exposed to several materials characterization techniques, such as UV-Vis and NMR spectroscopy, SEM, DSC and DMTA, while training sessions and group meetings facilitated knowledge exchange and collaborations. They participated to international conferences, schools and industrial visits, fostering multidisciplinary collaboration and expanding research networks. A summer school was held in Wien. The school was accessible online for partners and secondees unable to attend in person. The school provided an excellent opportunity to bring together ESRs and ERs to share ideas and expertise and maximize knowledge sharing. The secondments resulted in promising outcomes, including publications and strengthened collaborations between institutions and industries. As regards DISSEMINATION, key aspects of the project were illustrated on the VIT website. The consortium has been very active in the communication of results to the scientific community. Up to now the number of publications in international scientific journal amounted to 3. All the papers published with acknowledgement to VIT have an open access, to maximize the dissemination of the results. Every dissemination action has been highlighted both on the social media and the website of the project, as well as on the ones of the involved groups and Institutions.
Circular economy technologies and business models present a range of economic opportunities while simultaneously yielding environmental and social advantages. Unlike the linear economy model, which primarily focuses on reducing systemic harm, the circular economy fosters a positive reinforcing cycle. Notably, recyclable thermoset plastics emerged as one of the World Economic Forum's ten emerging technologies in 2015, highlighting their significance. Additionally, vitrimers garnered recognition with the 2015 European Inventor Award, underscoring their potential to usher in a new era of ecological plastics. This underscores the pressing need for a skilled workforce capable of maximizing the recycling potential of thermosets, thereby enabling the establishment of ambitious EU circularity targets to ensure the competitiveness of the plastics industry on the global stage. The main aim of the VIT action is to form a group of innovative and highly skilled research leaders who will drive innovation in the European economy and society by working across disciplines and sectors. During the initial period, the fellows involved in the secondments undertook extensive personal development and training activities, both in academia and industry. These included participation in monthly group meetings, seminars, and other scientific exchange activities, as well as networking initiatives. Several actions were planned to foster cross-fertilization and sharing of ideas and knowledge among the consortium and beyond. The scientific achievements attained during this initial period of VIT address some of the challenges and offer alternatives to the use of thermoset materials available on the market. Notably, recyclable insulation cables with electric and thermal properties comparable to those of the currently used cross-linked polyethylene were developed. These achievements are the result of concerted efforts, proficient interactions and robust collaborations among the partners.