Baroplastic Effect of Aliphatic Polyester Block Copolymers for Degradation-Free Multicycle Processing of Poly( <scp>l</scp> -lactide)

Advancing sustainable plastics is crucial to achieving a circular plastic economy. Baroplastics, block copolymers exhibiting order-disorder transitions under pressure, allow polymer processing at ambient temperatures, reducing energy use and avoiding thermal degradation. Their application, however, has been limited by structural constraints. This study introduces poly(<i>ε</i>-caproclactone-random-5-ethyleneketal <i>ε</i>-caprolactone)-<i>block</i>-poly(l-lactide) (PmCL-<i>b</i>-PLLA) as a "<i>baroplasticizer</i>" for nonbaroplastic PLLA. Blending with the block polymers lowered PLLA's flow temperature by up to 100 °C (160 to 60 °C at 50 MPa) while preserving molecular weight after repeated pressure cycles, ensuring recyclability. The improved formability would arise from a pressure-induced ordered (solid)-to-disordered (melt/solid) phase transition. This work eliminates structural constraints in baroplastics, enabling broader low-temperature processing applications and advancing sustainable polymer technologies.