Branchy molecules make precise pores

Self-assembly is one of the most practical ways to construct things at the molecular scale.

Researchers from the University of Toronto have found a way to coax a material containing microscopic pores to assemble from two very different types of molecules.

The material could be used as packaging material for microscopic electronics, to store gases, and to deliver tiny amounts of drugs to very specific places, according to the researchers.

The material is made from a mix of the inorganic silica material alkoxysilyl and dendrimers, which are branched organic molecules that can be used to make templates for complicated porous structures. Organic molecules contain carbon; inorganic molecules do not.

The researchers found a way to use the self-assembling dendrimers to direct the inorganic molecules into a useful structure. The silica molecules attach to the outermost branches of the dendrimers, which link up to form a layer around cylindrical templates. The researchers made materials with 8.2-nanometers and 9.1-nanometers diameter regularly-spaced pores.

The material could be used practically in five to ten years, according to the researchers. The work appeared in the November 26 issue of Science.