TEAM 1: POLYMERIZATION CATALYSES & ENGINEERING
Polymerization catalysis has been a key area of research in LCPO for more than 20 years. This research topic covers organometallic, organic and enzymatic catalysis but is also dedicated to the polymerization in dispersed media.
Metal-Free Approaches in Polymerization Catalysis
Besides polymers obtained by radical polymerization, most of industrial polymers are produced following a metal-based approach. As a consequence, these polymers are often contaminated with more or less toxic metal residue, thus limiting some applications in biomedicine, electronic or food industry.
To overcome these drawbacks, new metal-free approaches for polymer synthesis are developed in LCPO. Besides being an alternative route for polymer synthesis, metal-free synthesis of polymer may also afford new monomer activation modes, while affording better control of the polymer physico-chemical properties.
We have developed several approaches based on organocatalysis with small organic molecules (Lewis bases: N-Heterocyclic Carbene (NHC), phosphine, guanidine…; Lewis acids; ambiphilic molecules) for the metal-free synthesis of polymers.
We are also strongly involved in the bio-inspired modification and synthesis of polymers as well as in the development of enzymatic catalysis
These new class of catalysts allow us to polymerize a variety of monomers including polar (meth)acrylate derivatives, cyclic esters, cyclic ethers but also non-polar monomers such as isoprene.
Better handling and recycling of these catalysts are expected from the development of masked catalysts and/or polymeric-supported versions that can in-situ deliver the active form.
Notably, polymeric-supported NHCs (poly(NHC)) can easily be prepared from their corresponding imidazolium-based poly(IonicLiquids) (PILs).
New Metal-Based Approaches in Polymerization Catalysis
Most of the polymers are produced with the use of organometallic derivatives. However, the toxicity of some metals associated with the need for increasing polymeric material performance and the limited development of metal-free routes lead us to develop new metal-based approaches for the synthesis of various polymers.
We are particularly interested by monomers able to polymerize with an anionic route since it favors the preparation of high interest polymers for major industrial applications such as polyether-based systems for soft or amphiphilic materials and polyamides for lightweight composites in future green cars.
We have shown that the formation of “ate” complexes could modulate the basicity of active centers and the activation of monomers, allowing the “retarded anionic polymerization” of styrene and dienes to proceed in bulk and at high temperature. The rapid controlled/living polymerization of substituted epoxides was also achieved, affording polyethers and copolymers with various properties. This concept is also being used in lactams polymerization for the preparation of high performance polyamide materials.
Please see the publication pages for a detailed description of our most recent research projects.
Polymerization in Dispersed Media
Polymerization in heterogeneous medium offers many advantages, among them easier heat removal, better viscosity control and easier recovery of the polymers formed. Today’s environmental concerns can be better addressed through the use of non-flammable, low cost and environmental-friendly solvents, ideally water. At LCPO, we investigate the formation of nanoparticles from polymerization of monomers in dispersed media, especially in water.
Precipitation polymerization route is explored to elaborate highly functional isometric crosslinked particles. Such particles display exceptional chemical functionality, outstanding mechanical properties and interfacial properties in Pickering emulsions and Langmuir-Blodgett films.
While radical polymerization has widely been carried out in dispersed processes, some high potential polymers (e.g. polybutadiene, polynorbornene, polycyclooctene…) cannot be prepared by this method. At LCPO, we have shown that Ring-Opening Metathesis Polymerization (ROMP) is a powerful and an innovative method to access novel nanoparticles family.
Nanostructured polymer composite particles were elaborated by a straightforward one-step, one-pot, one-catalyst route, based on the simultaneous combination of ROMP and ATRP in aqueous dispersed media. Currently, we are developing “smart” materials (or nanoparticles) able to response to external or internal stimuli. Various processes, such as macro-, mini-, micro-emulsions, suspension and dispersion are being investigated to design specific polymers for targeted applications.