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Chimie et Design Macromoléculaire (CDM) team
The research activities of the Chemistry and Macromolecular Design (CDM) team are focused on the design and study of polymer systems with innovative physicochemical and thermomechanical properties. Our work is organized around four themes, which overlap in many ways.
Theme 1. Networks and formulations incorporating dynamic covalent bonds
The design and study of polymer systems containing dynamic covalent bonds is one of the central themes of the CDM team’s activities. One line of research involves the development of new exchange chemistries. This work, carried out independently or in collaboration (with the CMC team of the C3M unit, Filip Du Prez’s group in Gent, Mathieu Pucheault’s team at ISM in Bordeaux, ANR PRC aBOVE, 2019-2023), has led to the development of new chemistries and the design of recyclable materials with innovative properties, injectable hydrogels and thermo-associative formulations.
A second line of research aims to deepen our understanding of these systems, and in particular to correlate molecular exchange dynamics, network functionality and topology with their macroscopic properties. Some of these studies have been carried whithin the DN ReBond (lien) or in collaboration with the group of Prof. Evelyne Van Ruymbeke (UCL, Belgium).
The CDM team also collaborates with industrial partners to study, transfer and optimize chemistries developed in a variety of fields.
Theme 2. Supramolecular assemblies
Supramolecular assembly is a powerful tool for creating next-generation functional materials. This approach is based on the exploitation of multivalent non-covalent interactions to form well-defined aggregates under targeted environmental conditions. Our motivation is to obtain recyclable materials that are both efficient to use and easy to process.
This paradigm is exemplified by our work on polyethylene. As part of the ANR PE-SUPRA program, carried out in collaboration with the CP2M laboratory in Lyon, we have modulated the thermal and mechanical properties of low-molar-weight polyethylene by functionalizing its chain ends with supramolecular units, dimerization of which leads to mesoscopic structuring.
In other ongoing lines of research, we are seeking to control the crystallization and adhesion of polyolefin blends by means of one-dimensional co-assemblies, or to exploit functional one-dimensional supramolecular polymers to improve the performance and shaping of dynamic covalent networks.
In collaboration with research groups in the Netherlands and Greece, our team is also seeking to identify the fundamental principles linking the structure and the chiroptic and viscoelastic properties of supramolecular coassemblies.
Theme 3. Synthesis methodologies
The topology and functionality of macromolecules are two key parameters for controlling the viscoelastic and mechanical properties of materials and formulations. The development of synthetic methods that allow the introduction of new functions and/or control of polymer topology via simple, robust or even solvent-free processes is one of the team’s research topics.
The synthesis of branched structures by telomerization and reactive processing of polymers are two examples. The latter is used, for example, to transform commercial polymers into vitrimers using a sustainable and economical process, or to recycle plastics and their mixtures without selective sorting. One example is our work on upcycling polyethylene and polypropylene blends using reactive extrusion. This theme illustrates the CDM team’s ambition to combine fundamental research and projects that have a strong societal impact.
Theme 4. Hierarchically structured polymers
The concept of hierarchical structures is another tool of choice, complementary to supramolecular assembly, for manipulating the physicochemical, viscoelastic, thermomechanical and optical properties of semi-crystalline and/or amorphous polymers, or their alloys. Reactive shaping, polymerization processes, phase separation, self-assembly of organic molecules or polymers, and dynamic covalent chemistry are all used to control the molecular, nanometric and micrometric structuring of polymers.
For example, by adjusting the photopolymerization kinetics of acrylate formulations, it is possible to create surface instabilities due to swelling of the film by residual monomers. The shape and size of the textures depend, among other things, on the thickness of the film or the intensity of the UV radiation. These morphologies give the coating tunable optical properties (blur and clarity).
IN the framework of the ANR PRC DYNAMEX (with the CP2M laboratory in Lyon), we have studied latex films, synthesized by the PISA (Polymerization-Induced Self-Assembly) process, incorporating dynamic imine bonds. The particles thus produced are composed of a hydrophilic shell and a hydrophobic core, the nature of which determines, among other things, the structuring and the mechanical and vitrimer properties of the final coatings.
Recently, we have also succeeded in inducing hierarchical structuring in semi-crystalline materials, via supramolecular coassembly processes. Using a combination of spectroscopic, microscopic, rheological, calorimetric, theoretical, and X-ray scattering techniques, we have elucidated how subtle changes in the sequence of a supramolecular coassembly dictate the polymorphism of a polypropylene matrix, namely an organization of molecules that extends over several orders of magnitude in terms of length.
These results form the basis for new studies focusing on the non-covalent structuring of complex polyolefin blends, particularly with a view to improving their mechanical properties after recycling.
Our team is also trying to exploit the concept of phase separation to modulate the chemical reactivity, for example during reactive processing of polymers, and the viscoelastic and mechanical properties of polymer materials.