*3.2. Fabrication of the PVDF Composite Nanofibers*

Composite nanofibers have been proven to act as effective mechanical supports and to promote osteoconduction in bone tissue regeneration [2,4]. In the present study, composite nanofibers were fabricated by electrospinning PVDF solutions containing different amounts of POSS–EGCG conjugate. The contents of POSS–EGCG conjugate in the mixed solutions were 0 (PVDF), 2 (PE02), 4 (PE04), and 6 wt% (PE06) with respect to the weight of the PVDF. In addition, the PVDF nanofiber containing 6 wt% of pure API-POSS (PO06) was also prepared as a control. The SEM observations revealed that thoroughly interconnected porous structures formed between the composite nanofibers (Figure 2). The average fiber diameter of the composite nanofibers, which was 1033 ± 270 nm for PVDF, 971 ± 262 nm for PE02, 936 ± 223 nm for PE04, 1094 ± 394 nm for PE06, and 1131 ± 281 nm for PO06, was hardly affected by adding the POSS–EGCG conjugate. In addition, the distribution of the POSS–EGCG conjugate in the PVDF composite nanofibers was observed using EDS. The EDS Si-mapping analyses of the composite nanofibers represented that the POSS–EGCG conjugate was homogenously distributed over the nanofibers and that a greater density of Si was detected on the PE06 nanofiber (Figure S2).

**Figure 2.** SEM images of (**a**) PVDF, (**b**) PE02, (**c**) PE04, (**d**) PE06, and (**e**) PO06 composite nanofibers. (**f**) Average fiber diameters of the PVDF composite nanofibers analyzed from the SEM images (*n* = 4).
