Microcellular open-cell poly(L-lactic acid)/poly(D-lactic acid) foams for oil-water separation prepared via supercritical CO2 foaming

Biodegradable polymer foams with excellent oil-water separation performance show significant advantages in the treatment of oily wastewater and oil spill cleanup. Herein, high-expansion poly(L-lactic acid) (PLLA)/poly(D- lactic acid) (PDLA) foams with microcellular open-cell structure were successfully fabricated by an eco-friendly supercritical CO2 foaming method. When the PDLA content was 2.5 wt% (D2.5), mesh-like structures which made cells connected appeared on cell walls due to the existence of stereocomplex crystals. The D2.5 foam prepared at 10 MPa and 115 degrees C had an expansion ratio of 41 and cell size of 48 mu m. The adsorption capacity was 12-45 g/g for oil/organic solvents and almost 0 g/g for water, which indicated that it could effectively separate oil from water. In addition, the adsorption capacity maintained around 84 % after 10 adsorption-desorption cycles. Moreover, the D2.5 foam exhibited a better heat resistance compared with PLLA foam. This work pro-vides a strategy for preparing fully bio-based and biodegradable foams applied to oil-water separation.