Synthesis of rodlike polysiloxane with hexagonal phase by sol–gel reaction of organotrialkoxysilane monomer containing two amino groups

A higher-ordered polysiloxane was prepared by the sol–gel reaction of (3-(2-aminoethylamino)propyl)trimethoxysilane in a hydrochloric acid aqueous solution without using any surfactants. The X-ray diffraction profile of the resulting polysiloxane showed three peaks with the d-value ratio of 1:1/√3:1/2, indicating that this polysiloxane has a hexagonal phase. The peaks shifted by changing the humidity. Therefore, we estimated that this hexagonal phase came from the stacking of a rodlike polymer with a Si–O–Si framework at the core and ammonium groups extruding outside. The TEM image of the polysiloxane showed a stripe pattern indicating an ordered arrangement. Because one repeating unit of the present polysiloxane has two ammonium groups, the ion-exchange capacity of this polysiloxane and viscosity of its aqueous solution were larger than those of the previous polysiloxane with single-ammonium group.