Periodic Reporting for period 1 - ESPERANTO (Enhancing the Sustainability of PhotopolymERs ANd phoToinduced prOcesses)
Reporting period: 2023-02-01 to 2025-01-31
Esperanto (Enhancing the Sustainability of PhotopolymERs ANd phoToinduced prOcesses) is a MSCA initiative in the field of polymer science. At the core of the project is photopolymerization, key enabling technology (KET) for coatings, adhesives, inks, packaging, electronics, and 3D printing. known as faster and more efficient than traditional processes, as use of solvents is limited, energy consumption is very low, set-up of the plants is simple. Thanks to these advantages, it has the potential to enter and innovate many sectors, including small and medium enterprises, which are large job creators and critical for industrialisation at an early stage.
However, although greener than most chemical processes, photopolymerisation still presents sustainability issues and technical limitations, namely:
• the reliance on fossil-based raw materials
• the migration of components during the service life of the products (posing severe limits to the use of this KET in medical and food applications)
• the use of potentially harmful UV light sources
• the limited applicability to thick/opaque samples or non-illuminated areas
• the scarce recyclability of photopolymers (which are mostly crosslinked materials, thus non-recyclable).
Esperanto has been launched to tackle these problems; after forming an intersectoral network of universities and industries, the following objectives (Fig. 1) were identified:
• Objective 1 (O1): synthesis of new raw chemicals for sustainable photoprocesses, i.e. safer photoinitiators and biobased oligomers for photoinitiator-free reactions, and development of innovative processes providing easily recyclable photocured materials
• Objective 2 (O2): original uses of photopolymerisation processes for the preparation of biobased and bioinspired coatings, adhesives, thick samples, nanofibers, foams, and for the implementation of polymer processing such as 3D printing and photocrosslinking. For enabling the full control of photoprocesses and increasing efficiency, the design of a general modelling framework is also included
• Objective 3 (O3): formation of a new generation of creative, entrepreneurial and environmentally conscious researchers, with advanced skills to lead and manage innovation, implementing a training through research, doctoral hard & soft skills courses, dedicated schools/workshops organised by the Consortium and interdisciplinary and transnational exchanges among partners, as summarised in Fig. 2.
However, although greener than most chemical processes, photopolymerisation still presents sustainability issues and technical limitations, namely:
• the reliance on fossil-based raw materials
• the migration of components during the service life of the products (posing severe limits to the use of this KET in medical and food applications)
• the use of potentially harmful UV light sources
• the limited applicability to thick/opaque samples or non-illuminated areas
• the scarce recyclability of photopolymers (which are mostly crosslinked materials, thus non-recyclable).
Esperanto has been launched to tackle these problems; after forming an intersectoral network of universities and industries, the following objectives (Fig. 1) were identified:
• Objective 1 (O1): synthesis of new raw chemicals for sustainable photoprocesses, i.e. safer photoinitiators and biobased oligomers for photoinitiator-free reactions, and development of innovative processes providing easily recyclable photocured materials
• Objective 2 (O2): original uses of photopolymerisation processes for the preparation of biobased and bioinspired coatings, adhesives, thick samples, nanofibers, foams, and for the implementation of polymer processing such as 3D printing and photocrosslinking. For enabling the full control of photoprocesses and increasing efficiency, the design of a general modelling framework is also included
• Objective 3 (O3): formation of a new generation of creative, entrepreneurial and environmentally conscious researchers, with advanced skills to lead and manage innovation, implementing a training through research, doctoral hard & soft skills courses, dedicated schools/workshops organised by the Consortium and interdisciplinary and transnational exchanges among partners, as summarised in Fig. 2.
The scientific activities of Esperanto started after enrolment of 13 PhD students (DCs). Six individual PhD projects address Objective 1 (O1). Three DCs are developing new sustainable and efficient photoinitiators for radical or ionic photopolymerisation: biobased macrophotoinitiators (thus non-migrating after photolysis) have been synthesised from vegetable oils; with a different approach to limit migration, photoinitiators have been immobilised onto silica particles to tune surface-initiated radical promoted cationic photopolymerization (SI-RPCP) of vinylethers and epoxides under visible light; the synthesis of innovative Photobase Generators has been successful, enlarging the platform of available anionic photoinitiators with better control of base release under light. As far as new photoreactive monomers are concerned, the present achievements of other three DCs are the synthesis of new products exploiting polysaccharides as precursors for photoinitiator free photopolymerisation and the synthesis of photoreactive resins assuring reversibility, i.e. forming covalent networks upon irradiation, which can undergo further modification, even after service life, leveraging on bond exchange reactions triggered on demand. Overall the activities for O1 are expected to enrich the platform of safe, biobased and environmentally friendly photopolymerisable chemicals.
For Objective 2 (O2), seven PhD projects are on-going. Two DCs are working on innovative photocured coatings: one has been developing conductive coatings by joining photocrosslinking of apolar acrylates in water after complexation with cyclodextrins, and photoreduction of metal precursors to form metal nanoparticles; the other one is gathering promising results in the field of superhydrophobic fluorine-free coatings by creating wrinkly surfaces and inducing migration of particles to the surface to further modify wettability. The remaining projects have the ambition to apply different photoprocesses to innovate the production of materials for different sectors: the outcome of each project is meant to be a prototype/demonstrator. Three PhD projects are demonstrating that frontal photopolymerisation can allow preparing thick specimens, namely: biocomposites to be used as adhesive in wooden materials, recyclable reshapable elastomers for personalized ear plugs, well-defined origami-like materials with spontaneous controlled curvature. Other two project are respectively exploring thio-urethane systems for ionic curing as an alternative chemistry for 3D printing, and combining photoinduced processes and electrospinning for robust membranes from rubber latex for water purification.
For Objective 2 (O2), seven PhD projects are on-going. Two DCs are working on innovative photocured coatings: one has been developing conductive coatings by joining photocrosslinking of apolar acrylates in water after complexation with cyclodextrins, and photoreduction of metal precursors to form metal nanoparticles; the other one is gathering promising results in the field of superhydrophobic fluorine-free coatings by creating wrinkly surfaces and inducing migration of particles to the surface to further modify wettability. The remaining projects have the ambition to apply different photoprocesses to innovate the production of materials for different sectors: the outcome of each project is meant to be a prototype/demonstrator. Three PhD projects are demonstrating that frontal photopolymerisation can allow preparing thick specimens, namely: biocomposites to be used as adhesive in wooden materials, recyclable reshapable elastomers for personalized ear plugs, well-defined origami-like materials with spontaneous controlled curvature. Other two project are respectively exploring thio-urethane systems for ionic curing as an alternative chemistry for 3D printing, and combining photoinduced processes and electrospinning for robust membranes from rubber latex for water purification.
The activities of the Esperanto DCs have shown promising progress and have been disseminated through conferences as poster presentations. As described before, preliminary results have been achieved, properly addressing the problems identified, such as the scarce platform of biobased, non-migrating photoinitiators, need of monomers/oligomers from renewable sources, limited recyclability of photopolymers (on demand and/or at the end of their service life). Several works are promising in tackling challenges, i.e. the implementation of chemistries suitable for obtaining photopolymers with relevant thickness (not submillimetric films), the adoption of ionic photopolymerisation in 3D printing, the preparation of fluorine-free coatings with advanced properties such as superhydrophobicity, the fabrication of origami structures having curvature obtained on demand. Moreover, some preliminary demonstrators such as fibrous membranes obtained combining electrospinning and photopolymerisation have potential application in new sectors, namely water purification.
Further experimental work is however needed to complete the individual tasks and ensure success of each project, communicating results through publications on peer-review journals, eventually patenting them in view of further industrial exploitation.
Further experimental work is however needed to complete the individual tasks and ensure success of each project, communicating results through publications on peer-review journals, eventually patenting them in view of further industrial exploitation.