Facile fabrication of hierarchical porous electrospun poly (L-lactic acid) fiber membrane via swelling-crystallization for oil adsorption

Electrospun biodegradable fibers have been attracting significant attention in various applications. Introducing a porous structure into these fibers enhances their surface area and thus extends their applications. Here, we report a facile route to produce a highly hierarchical porous fiber structure from biodegradable electrospun solid poly (L-lactic acid) (PLLA) fibers by acetone-induced swelling-crystallization. By controlling the concentration of acetone solution and immersion time, the highly hierarchical porous PLLA fiber membrane with a very large surface area of 138.06 m² g⁻¹ and a high pore volume of 0.593 cm³ g⁻¹ was fabricated. Furthermore, we demonstrated that the porous PLLA fiber membrane presented a high oil adsorption capacity of up to 27.0 g g⁻¹, surpassing the performance of solid electrospun PLLA fiber membranes by approximately 34 %. The highly oil-adsorptive porous PLLA fiber membrane outperformed many conventional porous materials. Therefore, the hierarchical porous PLLA fiber membrane has high potential as an eco-friendly material for high-oil adsorption applications.