ETH puts nanopore and UF technologies out for licence

The Swiss Federal Institute of Technology (ETH) in Zurich last week invited applications to licence a technology that allows production of thin metallic silver films/coatings (0.5-5 μm thickness) with open nanopores.

These nanoporous silver membranes can be used as filtration membranes with a cut-off range of 50-200 nm and with high solvent or temperature stability. The technology is promising for filtration applications which require electrical charging of the filtration membrane.

A silver-containing ink formulation is the key part of the invention, which can be applied on basically any substrate by printing, roll-coating or spraying and be transformed into a highly conductive and highly porous silver film by a low-temperature treatment. Such nanoporous silver films provide a high specific surface area and good electrical conductivity.

To date the preparation of such nanoporous metal films or coatings involve complex processing steps and vacuum deposition technologies. As an additional drawback, nanoporous metal films prepared by conventional techniques usually exhibit cracks.

The invention is based on composite nanoparticles containing silver and calcium carbonate. Corresponding inks/dispersions of these particles allow the deposition of nanocomposite films on a substrate by applying and drying the ink.

Earlier this year, the ETH also put out for licensing a technology to produce porous polymer membranes for ultrafiltration or viral filtration by a new and simple high-speed fabrication process. Soluble carbonate nanoparticles which act as a pore template are the key part of the invention.

The incorporation of such nanoparticles into a polymer solution allows the fabrication of polymer membranes by well-known roll coating processes and a subsequent single-step dissolution of the carbonate template particles results in the formation of interconnected nanopores.

This process can be applied for different polymers (PES, PSU, PC) and the structural characteristics like pore size only depend on the pore template nanoparticles used. The molecular weight cut-off (tested by dextrane standards) correlates well with the primary particle size of the carbonate nanoparticles and can be tuned between 10-100nm.