Fabrication of Low-Density Silicone Rubber Foams for Oil Absorption via Synergistic scCO ₂ Foaming and Polymer Leaching

This study presented a novel method for preparing low-density silicone rubber (SR) foams by combining supercritical carbon dioxide (scCO2) foaming with polymer leaching, using water-soluble poly(ethylene glycol) (PEG) as an expandable porogen. During foaming, PEG swelled in scCO2, increasing the template volume, and its subsequent removal further reduced the foam density. The effects of formulation and foaming parameters the on cell structure were studied. SR foam with an expansion ratio of up to 8.4 was successfully fabricated. The foam also exhibited a volumetric swelling ratio of 4.96 and reached swelling equilibrium within tens of seconds. By combining low density with high swelling property, the foam exhibited absorption capacities ranging from 4.8 to 37.2 g/g for various oils and organic solvents, along with recyclability and selective absorption capability. This study provides a new and green technological pathway for developing high-efficiency oil–water separation materials.