Superimposed effects of nano-scale of ultra-thin glassy polymer membranes

Superimposed effects of nano-scale confinement and penetrant on behavior of ultra-thin glassy polymer membranes

Master/Bachelor assignment

In membrane based separations, especially in gas separation branch, there have been a long tendency to reduce the thickness of a selective layer to very small dimensions. The reason is that in case of a thin film membrane the mixture to be separated is able to achieve higher flows, so called fluxes, and therefore, the whole process is more effective. That of course translates also into cost efficiency and other technological benefits. In order to fully use the advantages of thin layers people nowadays try to reduce the membrane thicknesses down to extremely small dimensions – very often much below 100 nm.

However, quite recently it was found that such a reduction of thickness of glassy polymers can have strong influence on its properties. Among these are glass transition temperature, mechanical properties (Young’s modulus) and also physical aging. All of these are very important in case of membrane applications and can result in unexpected behavior of ultra thin films. Moreover, industrial separations very often involve atmospheres of highly interacting gases like carbon dioxide or volatile hydrocarbons. They are known to be a cause of plasticization of membranes which effect can further enhance the reduced thickness influence.

The aim of the project involves novel approach to understand the superimposed influence of high pressure penetrant and reduced thickness on the performance of ultra thin films. Most of the attention will be put on preparation and sorption measurements of ultra thin films of special classes of polymers used in membrane separations: polysulfones and poly(ether)imids.

Because of the high demands of polymer films of thickness in the range below 100 nm appropriate techniques have to be used. One of them is In-situ Spectroscopic Ellipsometry which allows extremely sensitive measurements of thickness and other properties of ultra thin films. The power of the technique can be fully utilized in studies involving high pressures and high temperatures which cover the conditions in which real technological processes are carried out.

Preferable background: Chemical engineering, Chemical Technology, Polymer chemistry.

For further information and inquiries please contact:

Dr. Ir. N.E. Benes n.e.benes@utwente.nl

M.Sc. Wojciech Ogieglo w.ogieglo@tnw.utwente.nl