SYNTHESIS OF MCM-41 WITH DIFFERENT PORE DIAMETERS WITHOUT ADDITION OFAUXILIARY ORGANICS

Swollen and highly ordered MCM-41 type materials with varied pores siz es, but with similar wall thicknesses, have been directly synthesized in the absence of auxilliary organics by controlling the preparation c onditions. The most important parameter in the synthesis in order to c ontrol the pore opening is the cetyltrimethylammonium (CTMA(+)) concen tration in the synthesis gel. Our results suggest that the mechanism o f swelling is related with the replacement of some CTMA(+) species by others cations in the interface formed between the liquid crystal and the silica surfaces. This approach could open new insights into the me chanism of formation of MCM-41 type materials as well as having in add ition an important impact on the preparation of large mesoporous mater ials.