Biodegradable Ultra-Large Expansion and High Open-Cell PLA/PBAT Foams Fabricated by Supercritical CO₂ Foaming for Selective Oil/Water Absorption

With the advancement of society, the issue of oil pollution is escalating, therefore we propose a straightforward and efficient approach for fabricating fully biodegradable poly (lactic acid) (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) foams with exceptional selective oil-absorption capabilities through the integration of melt blending and supercritical CO₂ (scCO₂) foaming techniques. The PLA90 foams, activated at 11 MPa and temperatures ranging from 105 ℃ to 110 ℃, exhibit an expansion ratio of 44 and a highly interconnected open-cell structure with an open-cell content exceeding 80%, effectively mitigating cell shrinkage occurrences. The 105 ℃-triggered PLA90 foam displays pronounced lipophilicity/hydrophobicity, accelerated oil-absorption kinetics, and elevated oil-absorption capacity. Specifically, the equilibrium absorption capacities for cyclohexane and silicone are 12.8 g/g and 20.1 g/g, respectively. Moreover, the maximum absorption capacity decline rate for silicone oil stands at a mere 13.4% over 10 absorption–desorption cycles. The findings presented in this study establish a theoretical framework and offer empirical evidence to support the development of fully biodegradable, high-performance, and reusable oil-absorption materials.