Fig. 5
Mechanism of the hierarchical bending, cyclization, and radial connection of the aggregates. After neutralizing the aqueous solution and removing the by-products before dialysis, all the samples are prepared from the neutralized aqueous solution unless otherwise noted. a TEM images showing the self-assembled evolution of POSS-SS-(PEG)8 with the concentration of 1 mg/mL in pH 8 solutions for various times. Insets are the correspondingly schematic structures. b SEM, c AFM, and d Cryo-TEM images of the monolayer vesicular formations at 12 h. Scale bars: 0.5 μm. e DLS results of the nanoparticles for various times. f The possible self-assembled mechanism of nanostructural bending, cyclization, and radial connection process. In this process, the longer cylinders can bend into the vesicles for conformational minimal energy. The whole formation process of the vesicles is clearly observed from the TEM images. On account of the limited space at the interior of the vesicles, the number, and density of disulfide bonds is significantly increased so that the possibility of thiol–disulfide exchange reaction is accordingly improved, gradually resulting in the radial connection to form the dense spheres. The orange cube represents the POSS core, the red ellipsoid represents the disulfide linkage and the cyan chain represents the PEG shell
