Polymeric membranes made without organic solvent – POMEWISO

POMEWISO project involved three partners (European Institute of Membranes, CEA and
IRSTEA); the project aimed at developing novel polymeric membranes without the use of
organic solvents by an original phase inversion method, i.e. temperature increase above the
upper critical solution temperature of the polymeric system. Water-soluble commercial
polymers like biobased cellulose ethers (hydroxypropyl cellulose) and poly(amic acids) or
modified chitosan have been used in the project.
The use of water soluble polymer was a challenge since (i) the phase diagrams are less
referenced and much more complex than those of classical polymers, (ii) the phase
separation processes are different, (iii) a crosslinking stage is necessary to fix the membrane
morphology and to prevent membrane solubilization during water treatment.
A multi-scale approach was developed to investigate the coupled phenomena during
membrane formation: (i) phase inversion, (ii) crosslinking, (iii) mass and heat transfer, (iv)
functional properties of final membranes.
The environmental assessment was conducted by IRSTEA with two objectives: (i) contribute
to the eco-design process and (ii) comparing POMEWISO process with a reference system for
manufacturing membranes. It was thus possible to achieve a simplified LCA calculator very
useful for ecodesign purposes in which all manufacturing parameters are customizable.

POMEWISO project allowed demonstrating the possibility to developing novel porous
polymeric membranes for water treatment, not only without the use of organic solvent, toxic
and difficult to remove, but also from bio-based polymers, in the field of green chemistry.
Very interesting filtration performances were obtained comparing to traditional polymeric
membranes, opening up new opportunities in water treatment applications.
This basic research project allowed to developing new synergies with industrial players in
the field of polymers, membrane manufacturing, and water treatment in oil and gas
industry.

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-Demonstrating the success of POMEWISO project, a patent was filed at the end of the project
(September 2014), dealing with the filtration properties of this new generation of polymeric
membranes.
Référence du formulaire : ANR-FORM-090601-01-01 9/25
Although the patent delayed the publication of the scientific results, the scientific production
of the project is:
- one patent,
- one scientific paper in Journal of Membrane Science (2014),
- 5 oral conferences in national and international congresses,
- 10 technical reports for the environmental assessment.

We propose to implement new processes of membrane manufacturing by using lower critical solution temperature (LCST) polymers and their demixion in water. Three classes of polymer including poly(amic acids) and modified cellulose and chitosan will be studied. After determining the phase diagrams, the mechanism of phase separations will be characterized and the growth laws with time established. This will provide roadmaps for the membrane manufacturing. A range of process parameters (temperature, air flow rate and relative humidity) in which porous structures are obtained will then be assessed. Relationship process parameters-membrane morphology will be investigated through a quantification of the mass and heat transfers. Modelling of transfers and numerical simulation of composition paths will be examined to find relationship phase separation mechanism-processing-morphology. Consolidation of the film structure can be carried out by either thermally or radiation induced cross-linking.
Finally, the functional performance properties including permeability and rejection will be determine for liquid permeation.