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SYNTHESIS OF ULTRA THIN MEMBRANCE LAYERS BY PLASMA TREATMENT OF LANGMUIR BLODGETT AND SELF ASSEMBLED FILMS

Objective


The project yielded a lot of highly interesting results from the technological as well as from the scientific point of view: Ultrathin films of high temperature stability and relatively homogeneous morphology have been prepared by a proper choice of the parameters of the plasma process. A deeper understanding of fundamental interactions between different kinds of plasma and a ultrathin LBlayer has been reached. Nevertheless, one of the main objectives, the preparation of an ultra-thin membrane film could not be reached, because it was difficult to transfer these promising results to technologically relevant types of membranes. Here, not only the complex interactions caused by the plasma had to be controlled, but, in addition, it was realized that many of the supports available are not ideal for LB transfer. Thus, at present it seems that such plasma converted LB-films have more potential for applications which do not demand transfer on porous substrates of large area, but where deposition can also be performed on small dense ones. This is the case in sensor applications where usually only very small areas have to be coated, so that the risk of cracks due to shrinkage and the defects is reduced substantially.

Furthermore, the hollow and flat ceramic membranes developed at TNO/CTK are already without additional coating of high interest for industrial applications in the field of ultrafiltration liquids. The same is true for some of the silicon dioxide and silicon nitride intermediate layers produced by LPCVD and plasma polymerization which showed remarkable selectivities for hydrocarbons and hydrogen. Distinct dependencies between gas permeation and membrane properties, e.g. layer thickness or process temperature, have been observed and can be used for a further tailoring of these membranes. Such layers are also highly mechanically chemically and thermally stable and could be a starting point for further developments in the direction of high performance gas separation membranes.
The proposed research is directed at the investigation of plasma induced processes in supported monomolecular (MM) films and to the evaluation of membrane transport and structural properties of plasma treated MM-films. The ultimate goal of the project is:

The development of a new generation of defectless, stable, quartz-like, metal oxide ceramic-like and functionalized ultra-thin(in 10A range)membrane coatings with a pore size up to the nm range and less than 1nm, which are useful in extreme conditions such as high temperature and pressure, with long-term stability under liquid separation process conditions. It is expected, that such membranes will operate on the basis of separation me mechanisms, known as "Molecular Sieve" and "Supercritical Liquefaction". The major research tasks are:

(i) Investigation of chemical and morphological transformations, induced in supported MM-films by low temperature plasma

(ii) Investigation of membrane properties of MM-films, transferred on microporous supports(MM-membranes),including lab-scale membrane separation experiments, modelling industrial separation processes, and the development of flow equations for process scale up.

New MM-membranes are expected to have a very high productivity (at least 10 times higher than known analogues) with persistent or enhanced selectivity.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Institut für Mikrotechnik GmbH
Address
Carl-zeiss-straße 18-20
55129 Mainz
Germany

Participants (2)

NCSR DEMOKRITOS
Greece
Address
Aghia Paraskevi Attikis Pob 60228
15310 Athens
TNO
Netherlands
Address
Den Dolech 2 P.o. Box 595
5600 AN Eindhoven