Effect of the solvent on the mechanical and structural properties of N-alkyldiamide organogels
Résumé
We study here organogels prepared thanks to a new organogelator, the N-oleyldiamide molecule which shows a remarkable propensity to gelify a large scope of solvents, from aprotic to high protic solvents. The solvent plays a key role in the formation and the stability of supramolecular self-assemblies. However the understanding and the control of its effects can be complex as many parameters are a priori involved. This study aims to understand the solvent effect on the organogels structures and on their final mechanical properties. Five solvent classes have been selected ranking from low protic to high protic, according to the Hansen H-bond parameter δh. The solvent proticity appears to be one of the main parameters that affects the organogel internal structure and therefore the final rheological properties. For a given organogelator fraction, the terminal elastic modulus measured by oscillatory rheology is observed to increase significantly with the Hansen H-bond solvent parameter δh. Materials of different mechanical properties are then shown to display various structures, which are investigated thanks to cryo-SEM. Besides, Wide-Angle X-ray Scattering (WAXS) has been used to probe the gelator organization at the molecular scale with regards to the solvent nature, in order to understand the supramolecular self-assembly of this promising molecule.
Domaines
Matière Molle [cond-mat.soft]
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