Shape Memory Temperature-Tunable Poly(butylene adipate-co-terephthalate)/Polylactic Acid Foams Prepared by Supercritical CO2 Foaming

Lightweight, shape memory temperature-tunable, biodegradable, and reusable poly(butylene adipate-co-terephthalate) (PBAT)/polylactic acid (PLA) foams with acetyl tributyl citrate (ATBC) were prepared by a simple, green, and efficient supercritical CO2 foaming technique. ATBC reduces the glass transition temperature (Tg) of PLA in PBAT/PLA composites and, thus, decreases the switching temperature of the shape memory in PBAT/PLA foams. ATBC widens the shape memory applicable temperature range, and the applicable temperature shifts toward lower temperatures. The minimum shape memory applicable temperature is 50 °C. ATBC can also accelerate the shape recovery process. In addition, increased shape memory temperature favors the shape fixing ratio (Rf) and recovery ratio (Rr) and can shorten the shape recovery time. PBAT/PLA foam exhibits a low density of 0.16 g/cm3, an Rf of 93.6%, and an Rr of 95.2%. PBAT/PLA foam also has reusability; both Rf and Rr remain above 85% after 10 cycles.