Sol-gel synthesis of rodlike polysilsesquioxanes forming regular higher-ordered nanostructure

Rodlike polysilsesquioxanes forming regular higher-ordered nanostructure such as hexagonal phase were prepared by sol-gel reaction of organotrimethoxysilanes having amino groups in aqueous solutions of inorganic strong acids. The XRD profiles of the resulting polysilsesquioxanes showed three peaks with the d-value ratio of 1 : 1/root 3 : 1/2, indicating that these polysilsesquioxanes have hexagonal phase. The diffraction peaks shifted by changing the humidity. In addition, the d-values of diffraction peaks increased by ion-exchange reaction with organic compounds such as fatty acid salt and anionic polymer. Therefore, this hexagonal phase originated from the stacking of rodlike polysilsesquioxanes with Si-O-Si framework at the core and ammonium groups extruding outside. This Si-O-Si framework probably formed a ladder or ladder-related structure, which was characterized by solid-state Si-29 NMR and IR spectrometries.