Synthesis of Biobased Poly(propylene 2,5-furandicarboxylate)-<i>block</i>-polycaprolactone for Stretchable Nanofiber Membranes Used in Oil–Water Separation

The increasing production of oil-contaminated wastewater poses a significant threat to the environment and human health; therefore, efficient oil–water separation technologies are needed. Electrospinning is a promising technology for oil–water separation whose raw material is partly derived from petroleum-based polymers, raising concerns about sustainability. This study aimed to develop a sustainable alternative, a biobased block copolymer Poly(propylene 2,5-furandicarboxylate)-block-Polycaprolactone (PTF-b-PCL), which was synthesized via direct esterification of 2,5-furandicarboxylic acid (FDCA), 1,3-propanediol (PDO), and polycaprolactone diol (PCL). The incorporation of flexible, lipophilic PCL chains into poly(propylene 2,5-furandicarboxylate) (PTF) significantly enhanced the copolymer’s flexibility and hydrophobicity. Electrospinning was employed to fabricate nanofiber membranes from PTF-b-PCL, which exhibited exceptional mechanical performance, including strain hardening and elastic recovery. The PTF-b-PCL-10 (PCL content: 10 wt %) membrane achieved high-performance oil–water separation, with a flux over 7774 L·m–2·h–1 and separation efficiency above 98.5% in multiple reuse cycles. Moreover, the membrane also maintained performance under tensile strain with a flux of 13,224 L·m–2·h–1 and adapted seamlessly to irregular surfaces without auxiliary support. The findings suggest that PTF-b-PCL nanofiber membranes are a robust and sustainable solution for challenging oil–water separation, especially in dynamic or nonuniform environments.