The aim of the project is to use for the first time Infra-Red light – in the Near IR (NIR) – to initiate photopolymerizations in dispersed media (emulsion and dispersion). The combination of the advantages of both dispersed media polymerizations and photo-polymerizations is powerful because the polymerizations could be carried out at room temperature or below, with minor risk of colloidal destabilization. Using an external light source also provides an external handle to control the polymerizations. The use of IR would side-step the limitations induced on shorter wavelengths by the light scattering caused by the nanoparticles formed, or by the direct absorption of the latter photons by the polymerization components (e. g. hybrid latexes containing UV-absorbing oxides or pigments). We will examine both linear IR absorption and multiphoton absorption, which provide complementary mechanisms for initiation.

The present project entitled « polytetra-aza » aims to : 1) Develop and synthesize original polymers based on the tetrazene function, with a bond sequence of three nitrogen bonds N-N/N=N/N-N. In order to incorporate the tetrazene moiety, as a repeating unit, in the main polymeric chain, we will use two synthesis strategies, either by polycondensation AA/BB starting from tetrazenic monomers, or by polyoxidation of bishydrazines. Accessing these tetrazenic and bishydrazinic monomers will be based on recent synthesis studies and preliminary results carried out at LHCEP. 2) Characterize the synthesized novel polytetrazene families and establish ageing studies on them in order to discuss their stabilities and their recycling into useful synthons by depolymerization. 3) Investigate some important properties stemming from the presence of the tetrazene moiety as a repeating unit within the polymeric backbone. a) We will test their capacity to chelate metal ions and to form metallo-polymer assemblies, and thus potentially to have new depolluting or catalytic polymers. b) We will explore the generation of N radicals by homolytic dissociation of the tetrazene motif, under acidic conditions, releasing N2 (g), and thus making it possible to initiate radical polymerizations.

The Halo-SF5 project aims to develop direct methods for the formation of C-SF5 bond that can be used in the synthesis of SF5-bioactive compounds. To do so, we envision to synthesis several halogen-SF5 (X-SF5, X= Cl, Br or I). Afterwards, the synthesized halogen-SF5 will be used for the formation of C(sp3)-SF5 and C(sp2)-SF5 through single electron transfer processes. Initial efforts will be dedicated to evaluate the reactivity of halogen -SF5 under electrochemical conditions for the formation of SF5 radical and subsequent use in Alkyl-SF5 synthesis. Afterwards, the use of dual strategy, transition metal/photoredox catalysis to forge C(sp3)-SF5 / C(sp2)-SF5 will be undertaken. In the one hand, we will access a highly interesting platform of aliphatic SF5 compounds by investigating the functionalization of nucleophilic carbon radical with transition metal catalyst. In the other hand, the synthesized X-SF5 will be used in the unprecedented direct synthesis of ArSF5.

The present proposal seeks to use pairing of Boranes with Lewis bases, forming classical Lewis pairs featuring dative bonds to i) generate H2-containing materials when amine-boranes are employed: H2 can be thermally or catalytically delivered highly pure at a temperature controlled by the polymer composition and structure and ii) stabilize precisely positioned radicals on polymeric materials via H-atom radical abstraction. We will code the properties using 2 strategies: 1) into the molecular ligated boranes prior or during polymerization; 2) into the Boron-containing (co)polymers using simple/robust post-polymerization functionalization. The polymer architecture and self-assembly will control the macroscopic properties of the materials, leading to improved or new functions. We thus aim at conferring properties to usual polymer scaffolds by introducing Boron-based Lewis pairs harnessing (mainly) radical copolymerizations of boronate-based vinylic monomers and polycondensations involving boranes. The PolyBora project abides by the fundamental research approach on the one hand (dynamic Boron-containing polymers featuring Lewis pairs) but also capitalizes on the knowledge generated through valuable applications: 1) storage / release of hydrogen in materials (identified societal challenge) ; 2) stabilization of radicals in materials (for applications such as DNP-assisted imaging/spectroscopy, for example).

The aim of the present proposal is to rationally design new boron-centered photo-initiating systems for a sustainable photopolymerization. In collaboration with an industrial partner, the polymerization of monomers, including those issued from renewable sources, will be achieved using visible light without resorting to expensive inert conditions. Existing radical photopolymerization processes are widespread in industry (e.g. for coatings, varnishes, paints, inks, etc.), but they rely on high intensity UV light sources and suffer from oxygen inhibition. Not only is this highly energy consuming, it also means that one cannot photopolymerize materials sensitive to UV light, such as pigments or inorganic oxides. Besides the lamp itself uses highly toxic mercury to function. The possibility to use industrially safer, low-energy irradiation systems based on visible light emitting diodes (LEDs) would constitute a significant breakthrough, as it would cut energy costs and avoid the use of expensive photochemical equipment. Near UV or visible light have a greater penetration depth and can pass through a wider range of materials than UV light, making it possible to have larger, less expensive reactors. For polymerization of pigmented media, this would also allow color printing without pigment degradation. Dry thin ink films as well as thick coatings and cure through volumes could be obtained, that are not accessible using existing technologies. However, because visible light cannot be absorbed by most of the commercial photoinitiating systems (PIS), there is an urgent need to introduce new photoinitiators (PIs) or photoinitiating systems with absorption profiles in the visible region. Building on previous collaborative efforts by the coordinator (P1) and partner 3, this proposal will seek to (i) introduce NHC-boranes which can be sensitive to LED light but remain compatible with polymerization in air; (ii) extend their use to visible light induced emulsion polymerization; (iii) expand the scope of photopolymerizable monomers to bio-sourced feedstocks.