The present technology allows to produce porous polymer membranes for ultra filtration (UF) or viral filtrationby 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 are only depending 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.
Background
UF and viral polymer filtration membranes are industrially produced by a process called phase-inversion. This technique is time-consuming and during the pore formation a number of parameters (e.g. humidity, temperature, time) need to be carefully controlled. Among others this is a reason why nanoporous polymer membranes are expensive.
Invention
The invention is based on carbonate nanoparticles such as calcium carbonate or strontium carbonate. Such very small carbonate particles dissolve very rapidly in an acidic solution under the evolution of CO2. This behavior makes these materials ideal pore templates for the fast generation of nanoscaled pores in polymer films.
Futures & Benefits
- Fast, robust and economic production process
- No need for precise temperature, humidity and pressure control, that is typical for phase-inversion processes
- Novel pore formation process can be integrated in high speed roll-toroll fabrication (> 1 m / 1 sec)
- Pore size adjustable between 10 nm - 200 nm, directly related to the size and amount of carbonate nanoparticles
- Easy change of polymer matrix (e.g. PES, PSU, PC)
- Process for flat membranes and potential for hollow fiber membranes
Field of Application
- Ultra filtration
- Viral filtration
- Protein concentration processes
- Low-cost filtration applications, e.g. water purification
- Functional textile membranes
More information: www.transfer.ethz.ch
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