Scalable non-solvent-induced phase separation fabrication of poly(vinylidene fluoride) porous fiber with intrinsic flame-retardation and hydrophobic properties

Advanced fibrous materials with intrinsic functional properties have been recognized as research hotspots in the field of functional fibers. Poly(vinylidene fluoride) with intrinsic flame-retardation and hydrophobic properties is the desirable fundamental material for functional fibers. In this paper, a novel poly(vinylidene fluoride) (PVDF) porous fiber endowed with flame retardation and hydrophobicity was fabricated through a continuous scalable wet spinning route. Based on non-solvent-induced phase separation theory, distilled water was employed as green non-solvent (coagulant solution) to solidify the nascent PVDF fiber. The morphology and structure of the resultant fibers were characterized by SEM, FTIR, XRD, BET, TG-DTG and DSC. The obtained fibers possessed similar diameter around 18 μm and numerous interlaced pore structure owing to phase separation. Two crystalline phases, α-PVDF and β-PVDF, of PVDF fibers were confirmed based on FTIR and XRD. The combustion performance and hydrophobic properties of PVDF porous fibers were evaluated by limiting oxygen index (LOI), cone calorimetry and contact angle, respectively. The results indicated that LOI of the PVDF fiber could reach 24.2, implying a remarkable flame retardation. Besides, the low density (0.86 g/cm3) and high contact angle (105°) of PVDF porous fibers endow durable floating and good hydrophobic properties. Therefore, PVDF porous fibers with remarkable intrinsic flame retardation and hydrophobicity can be recommended as a reasonable candidate for thermal-protective garment for life jackets.