Reprocessing Cross-Linked Polyurethanes by Catalyzing Carbamate Exchange

David J. Fortman, Daylan T. Sheppard, William Dichtel*

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

The reprocessing or recycling of cross-linked polymers by incorporating dynamic covalent cross-links has the potential to increase their usable lifetimes and reduce their environmental impact. Polyurethanes (PUs) are among the largest class of cross-linked polymers, making up 31% of the thermosetting materials market in 2012; however, their direct recycling into similar value materials is not well developed. We demonstrate that several Lewis acid catalysts mediate urethane exchange, likely via a dissociative mechanism, selectively and under mild conditions. Incorporating these catalysts into cross-linked polyether and polyester PUs with structures similar to commercial PU thermosets gives cross-linked materials that can completely relax stress in 100 s at temperatures as low as 140 °C. The dynamic polymers were reprocessed via compression molding to provide materials with similar cross-linking densities to as-synthesized materials. Because these systems are based on commercially available PU monomers and inexpensive Lewis acid catalysts, we anticipate that these findings will enable the recycling of traditional thermosetting PUs.

Original languageEnglish (US)
JournalMacromolecules
DOIs
StateAccepted/In press - Jan 1 2019

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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