CHEM 1270H: TOPICS IN INORGANIC CHEMISTRY
MESOCHEMISTRY: SYNTHESIS IN “INTERMEDIATE” DIMENSIONS
Geoffrey A. Ozin, Materials Chemistry Research Group, University of Toronto
This purpose of these four lectures is to introduce the key physicochemical design
principles that underpin the template directed synthesis of inorganic mesoporous
materials with particular structure, composition and form, and to appreciate how the
properties of materials fashioned at this length scale can be orchestrated to create a
purposeful function that is directed to a specific field of use.
It will be clear from examples presented that surfactant and block copolymer templates
enable “morphosynthesis: shape synthesis” of mesostructured materials with uniquely
curved form and patterned surfaces, in contradistinction to Platonic form, more typical of
materials structured at the microscale. The attribute of curved form is accomplished
through judicious command of topological defects in “inorganotropic liquid crystal
seeds” formed in the template directed nucleation and growth process.
Synthesis conditions can be adjusted to control the texture of the material comprising the
mesostructure to be either “glassy or crystalline”. Chemical and physical properties of
the mesostructure can be tailored through the inclusion of specific guests within channel
spaces or the incorporation of organic functional groups either on the surface of channels
or within channel walls. This capability enables “chemistry in or of the channels” as well
as “chemistry control of the physical properties of the composite”. Matching a
characteristic dimension of the templating mesophase to the length scale at a growth
interface, for example air-liquid, liquid-liquid and liquid-solid, called “mesoepitaxy”, can
be used as a synthesis tool to direct the orientation of and to pattern a mesostructured
film, for example by soft lithography, micromolding, photolithography and ink jet
printing, for a range of perceived applications that include battery, fuel and solar cell
electrodes and electrolytes, sensing and chemical delivery, low k microelectronics
packaging and acoustic insulation, and perm-selective membranes and catalyst supports.
In the framework of materials chemistry inorganic materials structured at the mesoscale
represent an “intermediate form of matter”, with unique properties. Mesomaterials of the
genre described in these lectures appear well poised to spawn new mesoscience and
mesotechnology. It will be interesting to watch the field unfold in the years ahead.