Photoredox Catalysts for Interpenetrating Polymer Networks Synthesis with Visible Light – VISICAT
The main advantage of Interpenetrating Polymer Network (IPN) for industrial application is to combine within a single material the properties of the two kinds of polymer networks generated by two different processes ie. cationic and radical polymerization. With the emphasis on resource and energy conservation as well as environmental issues, IPNs will be synthesized through photopolymerization in mild irradiation conditions as this type of polymerization can help to overcome quite all the drawbacks of classical photopolymerizations. As the next generation of benchmarked photoinitiators will clearly be those operating under visible light (for safety requirements), VISICAT will propose new Photoredox Catalysts (PC) that absorb visible light (ranging from 390 nm to 800 nm depending on the chemical structure) and can lead to a very efficient initiation of the photopolymerization reaction of both cationic and radical polymerizations. The main advantages of PC are: 1) the use of a very small quantity of product (good for toxicity and migration issues), 2) their high efficiency (working at low intensity and with visible light) and 3) their versatility (possibility to initiate both FRP and CP). In this project, molecules with long lived singlet excited state absorbing in the visible will be used as photoredox catalysts in order to improve greatly the reactivity with the redox coinitiator. Very preliminary results have shown the validity of this strategy (unpublished data). The final aim of the project is the creation of IPNs with tunable properties and with a new synthesis process using visible light. None of the PC proposed in this project has been reported in the literature as a photoinitiator of FRP and CP. Numerous monomers will therefore be tested with the new photoinitiating systems and the mechanical properties of the final polymers will be extensively studied to assess all the advantages obtained by the formation of an IPN structure over classical polymers obtained through FRP or CP, such as surface tackiness, shrinkage, Tg, adhesion, abrasion resistance, hardness, Young modulus, final color… The last year of the project will be mostly dedicated to the development of the industrial viability/applicability of the project with an optimization of the synthesize routes for the best photocatalysts with the aim to reduce the production cost and/or to improve the synthesis yields. In parallel, a screening of the experimental conditions found in many end-user applications (addition of charges, pigments, water…) will be done in close collaboration with the technology transfer office (TTO) to evaluate the possible market to address for these new PCs incorporated in a polymerization process induced with visible light. At the end of this ANR, the goal is to patent the best systems with the TTO in order to propose them to the targeted industries. From the originality of the approach, publications in high impact journals can also be expected.
To conclude, this ambitious project associates the complementary expertise in organic chemistry, photochemistry, polymer chemistry and photopolymerization of two academic research groups with worldwide reputations in their respective fields. From the excellent complementarities/synergies between the different partners, the development of resins with outstanding reactivity for IPN synthesis under visible light can be expected.
Madame Céline Dietlin (Institut de Sciences des Matériaux de Mulhouse)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
IS2M Institut de Sciences des Matériaux de Mulhouse
ICR Institut de Chimie Radicalaire
Help of the ANR 375,733 euros
Beginning and duration of the scientific project:
- 48 Months