posted on 2021-11-11, 19:03authored byJean-Emile Potaufeux, Jérémy Odent, Delphine Notta-Cuvier, Sophie Barrau, Chiara Magnani, Rémi Delille, Chunbo Zhang, Guoming Liu, Emmanuel P. Giannelis, Alejandro J. Müller, Franck Lauro, Jean-Marie Raquez
Even
though reversible interactions within ionic hydrogels are
well-studied, underlying mechanisms responsible for the high-value
added performance of ionic nanocomposites remain almost unexplored.
We herein propose a fundamental understanding aiming at elucidating
the mechanism behind the reversible breaking and reformation of ionic
bonding in the case of organic–inorganic hybrids made of a
combination of imidazolium-functionalized poly(ethylene glycol)-based
polyurethane (im-PU) and surface-modified sulfonate
silica nanoparticles (SiO2–SO3H). Such
ionic hybrids already demonstrated unique features related to the
presence of electrostatic interactions, but the underlying mechanisms
governing the overall material performance have never been discussed.
To dissociate the reinforcement role of nanoparticles and ionic interactions,
either standard nonionic SiO2 or ionic SiO2–SO3H nanoparticles were introduced into im-PU.
Mechanical performances, thermal transitions, relaxation processes,
and the morphology of the hybrids were deeply investigated to better
comprehend the mechanisms at the origin of the ionic material reinforcement.
In addition, a mechanistic investigation is proposed to quantify the
dissipation energy ability of the as-proposed ionic hybrids, and an
approach is presented to identify a characteristic time for restoration
of reversible ionic bonds under different loading scenarios.