Both high-resolution and scanning transmission electron microscopy (HRTEM and STEM) measurements were performed to further understand the nanostructure of the cross-linked hybrid films. As shown in Fig. 3c, the HRTEM measurements revealed the existence of very small nanodots that are randomly distributed with various sizes (1~3 nm) in the cross-linked hybrid (X-ASiO-PVPNP) films (see also Fig. S2a,b). Further HRTEM measurement with high magnification showed that the small nanodots consist of a particular lattice nanostructure with an inter-lattice spacing of ca. 0.15~0.2 nm, indicative of highly ordered states (see the bottom images in Fig. 3c). Interestingly, as shown in Fig. 3d, the nanodots were identified as the PVP domains by the STEM measurement through the composition analysis (see the focused area in Fig. S2c). Because the nanodots exhibited dark spots in the HRTEM images and bright spots in the STEM images, they are confirmed a well-ordered phase that is sufficient to make proper electron diffractions45. Taking into account the TEM analysis results, it is supposed that the nanodots consist of well-ordered PVP chains as illustrated in Fig. 3d (right). This well-ordered state could be made via nanoscale-phase separation processes during sol-gel and thermal cross-linking reactions because of the increased viscosity leading to the different surface energy between the PVP phase and the ASiO precursor sol phase.