Porous materials consist of a hollow framework. The voids in this framework are called pores. Depending on their pore width, they are classified as microporous materials , mesoporous materials and macroporous materials . The most typical mesoporous materials are composed of silica or alumina.
What is so special about Mesoporous materials?
First of all, these materials have very high surface areas, making them interesting for applications in Catalysis.
Here are some other reasons that make high surface area particularly interesting-
1) Their pore structures can be controlled. With control over this, they can be used for controlled release of the loaded actives.
2) Their pores can be loaded with various actives, such as drugs, vitamins, flavors or fragrances. As a result with certain modifications, they can be used for encapsulation and controlled release these actives. This special property makes them very exciting for the pharmaceutical, cosmetics and the food industry.
3) Their external surface can be modified with functional groups. This property can be applied in targeting them. For example, by conjugating the external surface with folates, these particles can be targeted towards cancer cells, which have folate receptors.
4) Their framework can be substituted with various metal oxides including silica, alumina, titanium and other metal oxides.
5) The internal surfaces of a mesoporous material can be functionalized with organics such as amino, thiol and carboxylic acid groups.
7) They possess an extremely narrow pore size with very high surface area.
How are they synthesized?
The synthesis of a mesoporous material involves replication of a surfactant liquid crystal structure followed by the polymerization of a metal oxide precursor. The organic surfactant is then removed through calcination, and this leads to a porous structure supported by a hard inorganic framework. By controlling the synthesis parameters, the structure of the template can be controlled. This makes it possible for these materials to have many different particle as well as pore structures.
Some Typical Properties of porous materials-
1) Uniform pore size distribution
2) High surface area
3) High pore volume
4) Controlled particle shape and size
5) 1D, 2D and 3D pore structures
6) High density of hydroxyl groups
7) Anchoring various functional groups on the framework
Because of these unique properties, porous materials can have a wide variety of applications in Pharmaceutical, Composites, Coating, Catalyst, Electronic, Optical, Magnetic and Energy Industries.