Mechanically tunable, damage-tolerant, and biodegradable poly(urethane-amide)s from post-consumer plastics via segmental composition regulation

Polyurethanes and their derivatives are versatile segmented polymers with tunable chemical structures and mechanical properties, enabling broad applications. However, conventional polyurethanes generally rely on non-renewable segments and often suffer from limited damage tolerance and poor degradability. Herein, we constructed a series of mechanically tunable, damage-tolerant, and biodegradable polycaprolactone (PCL)-based poly(urethane-amide)s (PCL-PUA) via polyaddition reactions using PCL diols with varying molecular weights (M n 530–4000 g/mol) as soft segments, aliphatic or/and aromatic diamide-diol chain extenders and hexamethylene diisocyanate (HDI) as hard segments. Both chain extenders were chemically recycled from post-consumer plastics, promoting the valorization of recycled feedstocks. By systematically tuning the soft-segment length and hard-segment composition, these PCL-PUA materials displayed regulated microphase separation behavior and distinct microphase-separated morphologies, leading to a transition in mechanical behavior from elastomeric to plastic characteristics. The optimized PCL-PUA achieved a high tensile strength (55.1 ± 1.8 MPa), an exceptional toughness (497.3 ± 13.6 MJ/m 3 ), and outstanding crack tolerance ability for material durability. In addition, the PCL-PUA materials exhibited enzymatic degradability for an end-of-life option and great potential in cushioning layer and adhesive applications. This work provides a design strategy for developing tough and sustainable polyurethane-based materials by regulating segmental composition and upcycling post-consumer plastics.