Abstract
Porous silica-based microspheres with pore surfaces functionalized by phosphonic acids are obtained for the first time from a direct co-condensation route using two alkoxide precursors (Si(OEt)4 and Si(OEt)3(CH2)2P(O)(OEt)2), surfactant self-assembly and spray-drying methods. The synthesis employs octadecyltrimethylammonium bromide as template agent. The post-treatment of the microspheres in boiling concentrated hydrochloric acid insures the hydrolysis of the ethoxy groups initially bound to phosphorus in the organophosphonate-siloxane precursor, without destroying the morphological and textural properties. Final porous materials have the chemical structure [SiO1.81(OZ)0.38]0.91[SiO1.35(OZ)0.29 (CH2)2P(O)(OH)2]0.09 (with Z @ H or Et), and posses interesting textural properties: SBET = 747 m2 g-1, and dp = 2.3 nm.