Synthesis of mesoporous silica using urea-formaldehyde resin as an active template

Urea (U)-formaldehyde (F) resin was prepared and used as an active template under acid and ethanol/water cosolvent conditions for synthesis of mesoporous silica, in which tetraethyl orthosilicate (TEOS) acts as the source of silica. The resin-silica composite particles and the gel product were achieved simultaneously in the procedure. The particle product with network structure was observed as the synthesis was performed in the initial F/U molar ratio region from 0.00 to 2.00, where the most amount of particles was yielded at the initial F/U molar ratio of 1.00. Synthesis performed at a high resin concentration with the initial F/U molar ratio of 3.00 yielded micron composite spheres as well. Although gel product could be obtained under all reaction conditions, the calcined gel product with controllable mesopore size and worm-like morphology was achieved only as the initial F/U molar ratio in preparation is above 1.00. Two model processes, i.e., continued deposition of monomers and cross-linking agglomeration between rigid resin cores were used in discussion of the synthesis mechanism. (c) 2006 Elsevier Inc. All rights reserved.