Entropy driven thermo-gelling vitrimer

TL;DR

This paper introduces a novel entropy-driven thermo-gelling vitrimer that remains liquid due to protector molecules, but transitions to a gel at high temperature through entropy-driven crosslinking, with tunable activation barriers.

Contribution

It presents a new vitrimer design with entropy-driven gelation, supported by a mean field theory and simulations, enabling stable high-temperature biomedical applications.

Findings

The vitrimer remains liquid due to protector molecules.

High-temperature gelation is driven by entropy increase.

Catalysts can tune activation barriers for gel formation.

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.