Reprocessable Polymer Networks via Thiourethane Dynamic Chemistry: Recovery of Cross-link Density after Recycling and Proof-of-Principle Solvolysis Leading to Monomer Recovery

By Lingqiao Li, Xi Chen, J. Torkelson. Macromolecules, 2019

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Polythiourethane (PTU) can be synthesized by a type of click chemistry involving the reaction of thiols with isocyanates. To our knowledge, thiourethane dynamic chemistry has not been significantly explored from a fundamental standpoint and has only begun to be studied regarding its use in producing recyclable, reprocessable substitutes for traditional cross-linked polyurethane networks. Using model compounds, we demonstrated the dual nature of the mechanism associated with catalyzed thiourethane dynamic chemistry: at elevated temperature, thiourethane groups undergo exchange reactions with free thiol groups and thermal reversion to thiols and isocyanates. We used this chemistry to synthesize cross-linked PTU elastomers which, upon optimization, achieve full recovery of cross-link density and tensile properties after multiple, relatively rapid remolding cycles. We characterized stress relaxation as a function of temperature and stoichiometric imbalance to provide insight into the mechanism of the network ...

Subfields: Materials Chemistry, Polymers and Plastics, Process Chemistry and Technology

View Paper: https://www.semanticscholar.org/paper/951db0f75209bb226b170b65880759ca3c849e04