Synthesis and Characterization of Foldamer-Based Networks
Lobnan Mazloum1,Ivan Huc2, Charles-André Fustin1
1UCLouvain – IMCN – BSMA, 1348 Louvain-la-Neuve, Belgium, 2LMU – Department of Pharmacy, 81377 München, Germany
Proteins can fold into defined 3D-structures which can exhibit unique mechanical properties, such as the elasticity of titin or the stiffness of collagen but are very complex objects. Foldamers, smaller artificial sequence-defined folded molecules, are mechanical elements able to undergo perfectly reversible conformational changes. These molecules unwind and rewind in a fully reversible manner under force while breaking intra-helix sacrificial weak bonds. Recent single-molecule force spectroscopy studies have demonstrated that helical aromatic oligoamides of 8-amino-2-quinolinecarboxylic acid, as small as 1 nm, exhibit exceptional elasticity, surpassing most natural helices. [1] Building on this discovery, our project aims to incorporate these aromatic oligoamides into polymer networks of varying topologies to investigate their impact on the rheological and mechanical properties of polymer gels.
The first targeted topology is an "ideal" network based on a 4-arm poly(ethylene glycol) (PEG) star with norbornene end-groups, enabling efficient conjugation with thiol-functionalized foldamers via photoactivated thiol-ene reaction. The second topology is obtained by cross-linkling linear polymer chains with the thiol-functionalized foldamers. Linear copolymers were synthesized by RAFT polymerization, with 2-Methoxyethyl methacrylate as a base monomer and N-Succinimidyl Methacrylate as a comonomer bearing an activated ester moiety. This copolymer was then functionalized with norbornene and subsequently cross-linked by the foldamers. Furthermore, we detail the synthesis of the oligoamide foldamers via solid-phase synthesis. Gels were successfully made using the synthesized pentamer as a cross-linker or the monomer as a non-helical model cross-linker serving as reference. Rheological measurements and mechanical tensile tests were conducted on the resulting gels.
References :
[1] F. Devaux, X. Li, D. Sluysmans, V. Maurizot, E. Bakalis, F. Zerbetto, I. Huc and A. Duwez, Chem, 7, 1-14, 2021. DOI: 10.1016/j.chempr.2021.02.030