Entropy driven thermo-gelling vitrimer

Abstract

Thermo-gelling polymers have been envisioned as promising smart biomaterials but limited to their weak mechanical and thermodynamic stabilities. Here we propose a new thermo-gelling vitrimer, which remains at a liquid state because of the addition of protector molecules preventing the crosslinking, and with increasing temperature, an entropy driven crosslinking occurs to induce the sol-gel transition. Moreover, we find that the activation barrier in the metathesis reaction of vitrimers plays an important role, and experimentally one can use catalysts to tune the activation barrier to drive the vitrimer to form an equilibrium gel at high temperature, which is not subject to any thermodynamic instability. We formulate a mean field theory to describe the entropy driven crosslinking of the vitrimer, which agrees quantitatively with computer simulations, and paves the way for design and fabrication of novel vitrimers for biomedical applications.

Asymmetric linker-mediated vitrimers

“…However, the system is entropy dominant at high temperatures, which means there should be a trade-o↵ between the system of energy dominant and the system of entropy dominant. In other words, the system is supposed to favour one kind of bond, which prevents cross-linking formation at low temperatures [24]. 14 3.2.…”