Highly porous fibers prepared by electrospinning a ternary system of nonsolvent/solvent/poly( l-lactic acid)

In this work, a facile method for fabricating fibers with micro- and nano-porous structure by electrospinning a ternary system of nonsolvent/solvent/poly( l-lactic acid) is presented. Poly( l-lactic acid) (PLLA) was dissolved in a mixture of dichloromethane (solvent) and butanol (nonsolvent) with a certain ratio. During the electrospinning, the evaporation of solvent and nonsolvent would take the composition of polymer fluid jet to enter the two phase region of the ternary phase diagram, since the solvent is more volatile than the nonsolvent. Thus the jet yielded to different phase separated structures, and further evaporation of the residual nonsolvent would lead to porous fibers.