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Polyurethane depolymerization by dialkyl carbonates: Toward sustainable chemical recycling
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DOI：10.1039/D5GC02533H.png)
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Abstract
En 中文
Polyurethane foams (PUFs); a major component of common consumer products such as mattresses; generally end up in landfills because they cannot be properly recycled. As thermoset; PUFs cannot be remolten to new products either. As condensation polymer; they can be depolymerized to recover one monomer; the polyol; but generally not the diisocyanate co-monomer without using phosgene; a toxic and wasteful reagent. We show here the possibility to depolymerize PUF in a way that enables a harmless; waste-free and phosgene-free recovery of both diisocyanate and polyol. Accordingly; the PUF is depolymerized with a dialkyl carbonate – providing carbonyl exchange at low concentrations of nucleophile – to deliver a carbonated polyol with 90% yield and aromatic dicarbamates with 70% yield under non-optimized conditions. These precursors are known to be converted to the original polyols and diisocyanates at high yield by alcoholysis and pyrolysis; respectively. We present advanced analytical methods to characterize and quantify the depolymerization products. We also report model reactions to show that the depolymerization proceeds through a thermodynamic equilibration of carbonates; carbamates and ureas.
Keywords:
polyurethane foams
depolymerization
diisocyanate
polyol
dialkyl carbonate
Journal
IF:
9.2
Papers:
1.3W
Citations:
7.6W
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