Degradable Polyurethane Foams Based on Amino Acid Phosphoramides (APtA)

Soft polyurethane foams are commonly found in furniture, mattresses, shoes and soundproofing applications. These crosslinked foams are hard to recycle. This paper describes our approach of introducing chemical breakage points based on amino acid phosphoramidates (APtA) in the PUs' backbones. The APtA monomers are combined with PEG, PPG and pTHF-chains to achieve different monomer structures. We demonstrate the hydrolysis of these APtA monomers at neutral pH 7 and the mass loss of the foams. It is shown that after 70 days, more than 50% of the p-THF-APtA monomer and 35% of the PPG-APtA monomer have degraded. However, a contrary trend was observed for the foams, with only 2.5% mass loss for the p-THF-APtA foam, but 26% mass loss for the PPG-APtA foam. The foams were also characterized using compression measurements, revealing a stiffer appearance of the p-THF-APtA foam compared to the foams based on PEG and PPG. SEM images were taken before and after the degradation of the foams to show the difference in morphology.