Data for Alkyl Substituted Polycaprolactone Poly(Urethane-Urea)s as Mechanically-Competitive and Chemically-Recyclable Materials

We report the mechanical performance and chemical recycling advantages of implementing alkyl-substituted poly(ε-caprolactones) (PCLs) as soft segments in thermoplastic poly(urethane-urea) (TPUU) materials. Poly(4-methylcaprolactone) (P4MCL) and poly(4-propylcaprolactone) (P4PrCL) were prepared, reacted with isophorone diisocyanate, and chain-extended with water to form TPUUs. The resulting materials’ tensile properties were similar to or superior to a commercially available polyester thermoplastic poly(urethane), and had superior elastic recovery compared to a PCL analogue due to the non-crystalline nature of P4MCL and P4PrCL. Additionally, monomers were recovered from the TPUU materials in high yields via ring-closing depolymerization using a reactive distillation approach at elevated temperature and reduced pressure (240–260 °C, 25-140 mTorr) with zinc chloride (ZnCl2) as the catalyst. The thermodynamics of polymerization were estimated using Van’t Hoff analyses for 4MCL and 4PrCL; these results indicated that the propyl group in 4PrCL results in a lower practical ceiling temperature (Tc) for P4PrCL.