Synthesis and characterizations of new negatively charged organic-inorganic hybrid materials: effect of molecular weight of sol-gel precursor

A series of negatively charged hybrid (organic-inorganic) materials were prepared through sol-gel process. The alkoxysilane-containing sol-gel precursors PEO-[Si(OEt)(3)](2)SO3H were obtained by endcapping polyethylene oxide (PEO) of different molecular weights with 2,4-diisocyanate toluene (TDI), followed by a coupling reaction with phenylaminomethyl triethoxysilane (ND-42) and sulfonation afterwards. The negatively charged precursors were then hydrolyzed and condensed to generate hybrid sol-gel materials, which were characterized by IR, TGA, XRD as well as the conventional ion exchange measurements. The results showed that in the hybrid sol-gel precursors PEO-[Si(OEt)(3)](2)SO3H organic PEO component was incorporated with alkoxysilane-containing ND-42 covalently. As the molecular weight of the precursors increased, thermal stability and cation-exchange capacity of the hybrid material decreased. All the hybrid materials were amorphous and those prepared from higher molecular weight precursors were flexible. (C) 2004 Elsevier Inc. All rights reserved.