Figure 1

SEM pictures of fibers and their surfaces fabricated by electrospinning 20% ( w / v ) PS solutions with various THF/DMF ratios. (A, B) 6:0, (C, D) 5:1, (E, F) 4:1, (G, H) 3:1, (I, J) 2:1, (K, L) 0:6, (M, N) 1:5, (O, P) 1:4, (Q, R) 1:3, and (S, T) 1:2, v/v. RH 60%, collecting distance 15 cm, feeding rate 1.5 ml/h, and applied voltage 12 kV.