Abstract
A new nanostructured and highly COOH-functionalized hybrid organic-inorganic material was synthesized by hydrolysis of oligomeric octahedral silsesquioxane (POSS) containing eight cyanopropyl groups. The hybrid elemental building block oligomeric octacyanopropylsilsesquioxane (CN-POSS) was synthesized from oligomeric octachloropropylsilsesquioxane (Cl-POSS) by an exchange reaction. The formation and the nanostructuration of the COOH-functionalized hybrid material were induced by non-covalent hydrogen bonding between COOH-POSS units without any decomposition of the core. The material was fully characterized by SEM, FTIR, 1H, 13C and 29Si solid state NMR, X-Ray diffraction and elemental analyses which confirm that the POSS core remains intact after each chemical modification step. TGA indicates also that the organic units are thermally stable up to 200°C. The activation energy related to the protonic conductivity of the COOH-POSS was evaluated and confirms the presence of strong hydrogen bonds. Finally, the accessibility and adsorption capacity of COOH groups towards transition metal ions were demonstrated underlining the potential of these hybrid materials in extractive chemistry.