POROUS inorganic solids find,vide application in, for example, catalys
is and separation technologies. One of the most promising routes to su
ch materials exploits cooperative interactions between a supramolecula
r organic template and inorganic precursor molecules to create an orde
red porous solid(1-7). This general approach offers considerable flexi
bility, and has led to materials with a wide range of bulk morphologie
s and controlled pore diameters spanning several orders of magnitude(8
-10). From a technological point of view, the preparation of such mate
rials in the form of mesoporous thin films is desirable, but attempts
to achieve this aim have been largely unsuccessful, resulting in disor
dered materials(11), Here we report the synthesis of thin (similar to
0.2-1.0 mu m) ordered films of mesoporous silica on freshly cleaved mi
ca substrates. The films are stable on removal from the substrate. We
propose a model to explain the formation of these films, in which the
surface structure and reactivity of the mica substrate controls the or
ientation of the micellar precursor species, which in turn imposes ord
er on the resulting solid film.