Figure 5
Silica microcoils prepared using PDI. (a) Molecular structure of PDI. (b) SEM image of silica microcoils at PDI/CMC-COOH ratio = 3; the arrows indicate elongated particles adhered to the coils. (c, d) SEM image of silica microcoils at PDI/CMC-COOH ratio = 0.2. The other initial weight ratios for the silica coating process were NH3(aq.)/CMC-COOH/TEOS = 300/0.37/10.1.