Surface Modification of Silica Particles with Calixarene

Calixarene was applied to surface modification of silica particles. Calix [4] arene with two alcoholic hydroxyl groups in the molecule (referred to as CADOL) was synthesized as a modification reagent. The surface of silica particles was modified by alkoxylation reaction with CADOL in xylene solution. The immobilized CADOL introduced the micro or ultramicro holes on the surface without changing the over-all pore size distribution of the material particles. The fundamental properties of the surface modification reaction with CADOL were examined in comparison to the alkoxylation reaction by aromatic alcohols.The modified particles were characterized by gas chromatograph and TPD measurement for chloroform. For the modified particles, the retention time of chloroform became longer and the separation factor of chloroform for the other molecules increased. The infrared spectra of desorbed gas showed the existence of strongly adsorbed chloroform on the modified surface. The introduced holes served as molecular cavities to enhance the interaction between the particle surface and chloroform molecules.