December 19, 2022
14:00
Louvain-La-Neuve
Auditoire A03 (Sciences)
Synthesis and rheology of double dynamic polymer networks based on metal-ligand interactions
Polymer networks are created by crosslinked polymer chains. These links can be covalent (permanent) or non-covalent (reversible) with consequent effects on the material properties. Both types of networks have advantages and disadvantages: covalent networks resist flow and creep but are difficult to process and recycle, while non-covalent networks are reversible but susceptible to structural changes in the long term. To overcome these limitations of individual networks, double networks work via the combination of a sacrificial network, which breaks immediately on stress and a structural network which maintains the overall integrity. In this way tough and strong materials are created. The subnetworks of a double network can be covalent or non-covalent, imparting new functionalities to the material. The dynamic nature of non-covalently crosslinked networks makes them an ideal candidate to be studied by rheology, which measures the time and frequency dependent behaviour of materials.
Our dynamic networks, studied in the melt state, are based on single and interpenetrating poly(n-butylacrylate) (PnBA) networks built from reversible crosslinks with largely different dynamics. The metallosupramolecular network, based on metal-terpyridine complexes, is highly tuneable according to the type of metal ion used. The dynamic covalent network, based on imine-aldehyde bonds, is slowly exchanging at room temperature and provides contrast to the more rapid metallosupramolecular network. Finally, the slide-ring network which facilitates highly extensible materials through the pulley effect is combined with the metallosupramolecular network. Through different combinations of networks and experimental parameters, we are able to establish a relationship between the structure of these networks and their viscoelastic behaviour measured by rheological techniques. In this thesis, our aim is to understand the dynamics of these networks individually and within the double network structure.
Jury members :
- Prof. Charles-André Fustin (UCLouvain), supervisor
- Prof. Evelyne Van Ruymbeke (UCLouvain), supervisor
- Prof. Sophie Demoustier (UCLouvain), chairperson
- Prof. Jean-François Gohy (UCLouvain), secretary
- Prof. Renaud Nicolaÿ (ESPCI, France)
- Prof. Salvatore Costanzo (Univ. of Naples Frederico II, Italy)
Pay attention :
The public defense of Rowanne Lyon scheduled for Monday 19 December at 02:00 p.m. will also take place in the form of a video conference