Tuning structural-response of PLA/PCL based electrospun nanofibrous mats: Role of dielectric-constant and electrical-conductivity of the solvent system

The role of optimum solvent systems on the fabrication of uniform, bead-free electrospun-nanofibrous-mats (ENMs) of polylactic acid (PLA), poly(ε-caprolactone) (PCL), and their blends, is investigated. The solvent systems influenced the fiber-diameters, morphology, crystallinity, thermal stability, hydrophobicity, quasi-static mechanical, and solid-state visco-elastic responses of the ENMs. Defect-free ENMs were obtained by using CF/DMF (80:20 v/v) binary solvent system while showing a relatively higher extent of crystallinity (PLA/PCL blend ∼ 34%), lower hydrophobicity (PLA ∼ 1170), higher strength (PLA ∼ 6 MPa), and moduli (PLA ∼ 305 MPa) for PLA and PLA/PCL blend systems whereas a higher strain-at-break (∼ 82%) was shown by PCL based ENMs. PLA/PCL blend based ENMs fabricated using DCM/DMF (80:20 v/v) solvent-mixture exhibited comparatively lower crystallinity (∼ 25%) but higher fiber diameter (1.03 ± 0.21 µm), strain-at-break (∼ 155%), and hydrophobicity (∼ 1300) compared to CF/DMF (80:20 v/v) system. Dynamic mechanical analysis (DMA) revealed the structural relaxation behaviors indicating the intrinsic structural deformability and flexibility of the mats. The study demonstrated the systematic role of solvent characteristics in terms of their volatility, dielectric constant, and solvent-mixture composition on the electro-spinnability and fabrication of high-strength, deformable, hydrophobic, bead-free ENMs with near monodisperse fibrous assemblies for biomedical applications.