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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. D. Parisi, Rijksuniversiteit Groningen, The Netherlands (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 research goal in the Parisi group is to understand the structural and dynamic properties of various (bio) polymeric and colloidal systems, in quiescent and under deformation conditions, to design and engineer materials for novel, impactful applications.
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 polyethylene (PE) and polypropylene (PP) vitrimers, the two most-produced polymers. Reactive extrusion, a solvent-free and industrially relevant process, will be used to transform commercial PE and PP into vitrimers.
In this frame, new reactive processing strategies and chemistries will be investigated, especially to address the degradation of PP associated to its radical grafting. Model PE and PP vitrimers will also be prepared by solution post-polymerization modification in order to study the impact of the distribution and degree of functionalization of PE and PP vitrimers on their processability, recyclability and thermomechanical properties.
The strategies and chemistries developed in the frame of the PhD will then be tested to recycle/upcycle PE, PP, and unsorted bends of polyolefins, some of the most critical challenges to be addressed to create a circular economy of plastics.
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 Chemical Engineering, Rijksuniversiteit Groningen, The Netherlands (https://www.rug.nl/research/enteg/)
Home institutions ESPCI Paris – PSL (France) and UCLouvain (Belgium)
Directors of research : Nathan Van Zee (nathan.van-zee@espci.psl.eu), Renaud Nicolaÿ (renaud.nicolay@espci.psl.eu), Daniele Parisi (d.parisi@rug.nl)
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.