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 degrees 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.