Polysiloxane resins modified by bisglycidyl calix[4]arene: Preparation, characterization, and adsorption behavior toward metal ions

Two porous polysiloxane resins were prepared by the ring-opening polycondensation of epoxy groups of bisglycidyl calix[4]arene with amino groups of polysiloxane microparticles that were prepared by the solgel method of cohydrolysis and condensation from gamma-aminopropyltriethoxysilane (RSC-I) or 4-aza-6-aminohexyltriethoxysilane (RSC-II) with tetraethylorthosilicate. The resins were characterized by elemental analysis, DR-Fourier transform infrared spectra, Raman scattering spectra, scanning electron micrographs, and thermogravimetric analysis. The porous polysiloxane resins exhibited high thermostability and preconcentration potential for divalent Cu, Pb, and Hg ions, especially for the trivalent auric ion, relative to both the special cavity and the network structure of polysiloxane resins. The nitrogen atoms in resins also exert some auxiliary action. The enthalpy of the adsorption of two resins toward trivalent auric ion was evaluated to be 6.83 and 8.04 kJ/mol for RSC-I and RSC-II, respectively. (C) 2005 Wiley Periodicals, Inc.