PhD : Synthesis of well-controlled amorphous vitrimers and their influence on the thermomechanical and linear viscoelastic properties of polymer matrices (H/F) — Offre pourvue

This doctoral thesis will take place in the Chimie et Design Macromoléculaire (CDM) team within the Chimie Moléculaire, Macromoléculaire, Matériaux (C3M, UMR 7167) laboratory at ESPCI Paris, France (2 years) and in the team of Prof. E. Van Ruymbeke, Bio and Soft Matter, IMCN at Université Catholique de Louvain, Belgium (2 years).
The CDM team is broadly interested in the design, synthesis and study of polymeric and composite materials organized at different length scales, with a particular interest in developing new materials.
The team of Prof. E. Van Ruymbeke aims to understand the dynamics and flow properties of complex macromolecules and supramolecular polymer networks.

Project description :
This PhD project is part of the European Doctoral Network ‘ReBond’, which involves eight Universities, five industrial partners and 15 PhD students.
By combining the expertise of the different partners in synthesis, advanced characterization, linear and nonlinear dynamics, mechanical properties, modelling, and plastic product development and processing, we shall uncover the underpinning relationships among processing and performance of vitrimer-based recycled plastics and elastomers.

The CDM team is deeply interested in a class of materials called vitrimers [1,2], which are permanent networks of polymer chains that are crosslinked with dynamic covalent bonds.
These materials are intriguing because they offer a compelling combination of physical properties.
For example, they behave like thermosets at use temperatures but flow like vitreous glasses at processing temperatures.
They typically exhibit excellent solvent resistance, recyclability, reshapability, and weldability, making them interesting targets in the context of realizing a plastics circular economy.
Although much progress has been made on the synthesis and characterization of vitrimers, many challenges remain [2].
For instance, vitrimers tend to be difficult to melt-process (e.g., extrusion) because of high viscosity.
On the basis of conventional methods, it is difficult to overcome the tradeoff between achieving good melt processability and high mechanical performance.

Within this framework, the specific objectives of this PhD will be to synthesize and characterize amorphous elastomeric and vitreous vitrimers with varying molar masses, degrees of functionalization and microstructure (statistical, gradient and block-like distribution of dynamic covalent bonds) with the aim to understand the relationship between functionality, crosslink distribution, processability and thermomechanical properties.
We will also develop novel synthetic approaches and design of vitrimers to obtain high-performance materials from existing plastics, including bio-sourced and renewable polymers.

The project contains experimental works and will be highly interdisciplinary.
It will encompass polymer synthesis and modification, advanced characterization (chemical, physicochemical and rheological), and materials science (processing and thermomechanical properties).

Required background : Applicants must have a master’s degree in polymer chemistry, physicochemistry or material science. Applicants should have a good background in polymer science.

Applicants must not have resided or carried out their main activity (work, studies, etc.) in France for more than 12 months in the 36 months immediately before their recruitment date (EU mobility rule).

Keywords : Vitrimers, polymer synthesis and functionalization, rheology, processing, thermomechanical properties.

Research unit : Chimie Moléculaire, Macromoléculaire, Matériaux, UMR 7167 (https://www.mmc.espci.fr/), ESPCI Paris, Paris, France Bio and Soft Matter, IMCN, Université Catholique de Louvain, Louvain-La-Neuve, Belgium (https://uclouvain.be/en/research-institutes/imcn/bsma)
Home institutions  : ESPCI Paris – PSL (France) and UCLouvain (Belgium)
Directors of research : Renaud Nicolaÿ (renaud.nicolay@espci.psl.eu)
Nathan Van Zee (nathan.van-zee@espci.psl.eu)
Evelyne Van Ruymbeke (evelyne.vanruymbeke@uclouvain.be)
Start date : October 2023 – March 2024

Literature references :
[1] Roettger, M. ; Domenech, T. ; van der Weegen, R. ; Breuillac, A. ; Nicolaÿ, R. ; Leibler, L. Science 2017, 356, 62-65.
[2] Van Zee, N. J. ; Nicolaÿ, R. Prog. Polym. Sci. 2020, 104, 101233.