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Exploring the impact of quinoline-based foldamers on the mechanical properties of polymer gels by Lobnan Mazloum -
Lundi 19 octobre 2026 à 15h00 - Salle Jean-Baptiste Carnoy (B.059) - Bâtiment Carnoy - Croix du Sud - 1348 Louvain-la-Neuve -
Polymeric materials are used in almost every area of daily life, creating a constant need to improve their properties and expand their application. Gels are a widely used class of polymeric materials, with applications ranging from food and agriculture to biomedicine. However, their mechanical properties can limit their use in more demanding applications, where materials need to combine strength, extensibility and toughness.
Nature, in contrast, produces soft materials with exceptional mechanical properties. Inspired by the mechanical strategies found in biological materials, the concept of sacrificial bonds and hidden length provides a way to accommodate deformation and redistribute mechanical work. Weak interactions can hold part of a molecule in a folded or constrained state. When a force is applied, these interactions can break before the main chain, allowing the molecule to unfold and release previously hidden length. Protein α-helices are interesting examples of molecular structures that can respond to mechanical force through reversible unfolding and refolding. They can unfold under tension and refold when the force is removed, while the covalent backbone remains intact.
Foldamers are synthetic oligomers that adopt the same helical folded shape and share many of these properties, while having a much simpler structure. Among them, quinoline oligoamide foldamers form particularly stable helical structures. Single-molecule force spectroscopy has shown that these helices have remarkable mechanical properties. They can unfold and refold repeatedly and very rapidly, releasing a substantial amount of hidden contour length with no energy loss.
This raises the question of whether the mechanical properties observed for a single foldamer can also be observed at the scale of a macroscopic material. To investigate this question, a quinoline pentamer was synthesized by automated solid-phase synthesis and functionalized for incorporation into a polymer network. The foldamer was used to crosslink four-arm poly(ethylene glycol) stars functionalized with norbornene groups through a light-triggered thiol-ene reaction. The resulting gels were characterized by rheology and tensile testing and compared with gels prepared using the corresponding monomeric, non-folding crosslinker. These measurements allow the influence of the foldamer on the macroscopic mechanical response of the network to be evaluated and provide insight into the consequences of its reversible folding and unfolding under deformation.
Jury members :
Prof. Charles-André Fustin (UCLouvain) (Supervisor)
Prof. Ivan Huc (CUP, Ludwig-Maximilians-University, München) (Co-Supervisor)
Prof. Yann Garcia (UCLouvain) (Chairperson)
Prof. Michael Singleton (UCLouvain) (Secretary)
Prof. Louis Pitet (IUMAT-AFP, UHasselt, Belg.)
Dr. Tetsuharu Narita (ESPCI, Paris, Fr.)
Pay attention : the public defense of Lobnan Mazloum will also take place in the form of a videoconference
