Membranes of epitaxial-like packed, super aligned electrospun micron hollow poly(l-lactic acid) (PLLA) fibers

Novel epitaxial-like packed, super aligned, mono-layered hollow fibrous membranes were prepared by co-axial electrospinning technology. PLLA pellets were dissolved in solvent mixture of dichloromethane and dimethyl formamide (DCM/DMF = 9:1) to prepare sheath solution dope with various concentrations (from 8 to 19 wt.%). Aqueous solution of poly-ethylene glycol (PEG) was used as core solution dope. During the electrospinning process, dope concentrations and feed rate ratios were adjusted, separately, to evaluate the formation of resulting membranes. With lower shell solution concentration (from 8 to 15 wt.%), the collected, flattened film showed arrangement of lower order. A stood-up film was clearly seen when concentration increased to 17 wt.% and higher. As the collecting time went longer, these fibers piled up and eventually, stood up as a thin film from the surface of collector. Increasing flow rate ratio (FRR) also resulted similar outcomes and verify the cause of this phenomenon. After washing with water, scanning electron microscopy (SEM) revealed sheets of mono-layered, micron-sized hollow fiber arrays which were well aligned and tightly packed, just like the epitaxial growth of some semiconducting materials. These perfectly aligned and tightly packed hollow fiber arrays can be considered as highly anisotropic scaffolds that mimic tissue structures, such as nerve tissue, vascular structure as well as other application.