Organosilicic Membranes Doped with Crown-Ethers.

Composite membranes have been prepared via the sol–gel process by controlled hydrolysis of ethyltriethoxysilane incorporating in the sol phase a selected crown-ether. The membranes are supported on borosilicate porous discs forming a continuous network as shown by scanning electron microscopy. The crown-ether (12-crown-4, 15-crown-5, 18-crown-6) remains homogeneously distributed in the organosilicic matrix as evidenced by IR and 13C NMR spectroscopies. A.C. impedance plots vary with the nature of the doped crown-ether as well as with the electrolyte used (alkali-metal chloride aqueous solutions).