Vitrimers Designed Both To Strongly Suppress Creep and To Recover Original Cross-Link Density after Reprocessing: Quantitative Theory and Experiments

By Lingqiao Li, Xi Chen, Kailong Jin, J. Torkelson. Macromolecules, 2018

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Vitrimers form a promising class of dynamic polymer networks, but they have an Achilles’ heel: elastomeric vitrimers exhibit significant creep under conditions where permanently cross-linked, elastomeric networks exhibit little or no creep. We demonstrate that vitrimers can be designed with strongly suppressed creep and excellent reprocessability by incorporating a substantial yet subcritical fraction of permanent cross-links. This critical fraction of permanent cross-links, which has little or no detrimental effect on reprocessability, is defined by the gelation point of only permanent cross-links leading to a percolated permanent network. Via a modification of classic Flory–Stockmayer theory, we have developed a simple theory that quantitatively predicts an approximate limiting fraction. To test our theory, we designed vitrimers with controlled fractions of permanent cross-links based on thiol–epoxy click chemistry. We characterized the rubbery plateau modulus before and after reprocessing as well as st...

Subfields: Polymers and Plastics

View Paper: https://www.semanticscholar.org/paper/2c6fe53353f000a15bf4084188a61f7bcaa7975f