*3.1. Morphology of PUSX Nanofibers Prepared for Physical and Biocompatability Evaluations*

In the previous study [10], we successfully prepared 12 kinds of PUSX nanofibers under the optimized conditions, and investigated the effects of solvents and solution concentrations on the as-spun nanofibers, along with the morphological appearance.

Representative SEM images of PUSX nanofibers are shown in Table 2. It can be seen that the surface morphology of the block-type PUSX was smooth and continuous, with fiber diameters ranging from 400 nm to 720 nm. The mean diameters decreased with the increase of both the chain lengths of silicone, and the silicone concentration. The surface morphology of graft-type PUSX nanofibers was also fine and continuous, with the mean diameters ranging from 460 nm to 560 nm. Compared with block-type PUSX, graft-type PUSX nanofibers did not show a clear influence of the chain length on the electrospinning parameters. Compared with the PU nanofibers, the PUSX nanofibers showed a more uniform surface with a smaller diameter, due to the hydrophobicity of the silicone group. In this study, the physical properties and biocompatibilities of the prepared samples are discussed.

**Table 2.** Scanning electron microscope (SEM) morphologies and average diameters of the PUSX nanofibers under the optimized electrospinning parameters (magnification: 2000×) [10].
