Functionalization of periodic mesoporous organosilica with ureidopropyl groups by a direct synthesis method

Ureidopropyl groups were used to functionalize the pore channels of ethane-bridged periodic mesoporous organosilica by the co-condensation of 1,2-Bis(triethoxysilyl)ethane (BTESE) and ureidopropyltriethoxysilane (UPTES) in the presence of Poly(ethylene glycol)-B-Poly(propylene glycol)-B-Poly(ethylene glycol) (P123) surfactants under acidic conditions. The final materials were investigated in detail by means of XRD, TEM, solid-state NMR, FT-IR and N2 adsorption, in order to study the effect of ureidopropyl groups concentration on their mesoscopic order and pore structure. The results show that bridging groups in the framework do not cleave and ureidopropyl groups are attached covalently to the pore wall of periodic mesoporous organosilica after functionalization. The mesoscopic order decreases with increasing amount of UPTES except for the sample with 20 mol% UPTES concentration, which exhibits a highly ordered two-dimensional hexagonal symmetry. The surface area and pore size decrease as the concentration of UPTES increases, but the materials with 20 mol% UPTES still preserve a desirable pore structure, with a surface area of 565 m2/g, a pore volume of 1.1 cm3/g and a mean pore size of 10.1 nm.