Novel Ultrafiltration Method

We have developed a scalable approach towards large scale fabrication of ultrafiltration polymeric membranes based on a two-step procedure: first, a polymer sheet containing soluble (degradable) carbonate nanoparticles is prepared and optionally brought into a specific form. The nanoparticles act as pore templates. In a second step the polymer film is turned porous by simple dissolution of the soluble nanoparticles upon contact to a mild acid.

Schematic of the production process

The pore formation of the resulting membrane is different than in conventional preparations: here, the pore size and number of pores can be exactly defined by the size and number of nanoparticles, as they serve as a direct template of the finally obtained pores. Therefore, the pore size can be tuned through the particle properties. The pore formation happens under well-defined conditions, separated from other processing variables. This may ultimately yield to narrow pore size distributions with associated improved selectivity.

Nanoparticle/polymer dispersion (A), transparent ultrafiltration membrane and electron micrograph

• continuous roll-to-roll processing
• pore size tunable (MWCO: 5, 70, 1400 kDa)
• pore formation < 10 s
• FDA approved material
• High quality low cost membranes for bioseparations, water treatment and packaging
• EP patent pending

Further reading:

• C.R. Kellenberger, N.A. Luechinger, A. Lamprou, M. Rossier, R.N. Grass, W.J. Stark, Soluble nanoparticles as removable pore templates for the preparation of polymer ultrafiltration membranes, J. Membr. Sci., (2011).

Patent:

• C.R. Kellenberger, N.A. Luechinger, W.J. Stark, Porous polymer membranes, EP application, January 2011.