Good news! Human ingenuity will take care of plastic trash!
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"Polyurethane, which is used in a wide variety of foams and spongy materials, is currently difficult to recycle. Part of the trouble is that it is constructed from two types of building blocks, respectively bearing oxygen- and nitrogen-linking groups, and most breakdown methods tend to cleanly recover just one of them. Hosgor et al. report that heating the foams in diethyl carbonate, which functions as both a reagent and solvent, together with zinc acetate as a catalyst, can deliver both the polyol (oxygen) and dicarbamate (nitrogen) components in 90 and 70% of respective yields."
From the abstract:
"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."
Polyurethane depolymerization by dialkyl carbonates: toward sustainable chemical recycling (open access)
Fig. 1 Overview of the full chemical recycling process
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