Green Fabrication of Biobased and Degradable Poly(lactic acid)/Poly(butylene succinate) Open-Cell Foams for Highly Efficient Oil–Water Separation with Ultrafast Degradation

Biobased poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) foams with excellent oil–water separation capability were fabricated using supercritical fluid foaming. PBS acts as the cell-opener and nucleating agent, and the introduction of a chain extender (a multifunctional epoxide oligomer, Joncryl ADR-4468, ADR) enhances the compatibility between PLA and PBS and improves the rheological properties of PLA/PBS. PLA with 6 wt % PBS (PLA/PBS6) exhibits a high expansion ratio of 52 and an open cell content of 97.9%. It is notable that different cell structures of varying sizes show significant differences in the adsorption capacity and rate. Compared to PLA/PBS9 foam with a similar expansion ratio and open-cell content, the adsorption capacity of PLA/PBS6 has increased from 18.8 to 24.5 g/g, but the adsorption rate constant decreased. Smaller cells are more effective at increasing the adsorption capacity, while larger ones are beneficial in reducing the saturation time. PLA/PBS6 foam shows a contact angle of 139° with deionized water, oil adsorption capacities ranging from 24.5 to 50.7 g/g, and retains 84.3% of its CCl4 adsorption capacity after 10 cycles. PLA/PBS6 foam degrades over 90% in 5 days in alkaline environments (pH = 13). The work provides a novel strategy for the green fabrication of ultralight foams with outstanding oil–water separation properties. It is expected to meet the requirements of different oil–water separation situations by regulating the cell structure and size distribution via controlling the adsorption capacity and adsorption rate.