(129f) Advanced Polymeric Membranes With Tailored Barrier Properties

Advanced polymeric membranes with tailored barrier properties

Mathias Ulbricht, Nadia Adrus, Sven Behnke, Sven Frost, Christian Kuhn, Aleksandra Gajda, Zhaoqin Pei

Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45117 Essen, Germany; mathias.ulbricht@uni-essen.de

Membrane technologies have been established in a wide range of industrial processes. However, in advanced separation and reaction engineering, membranes applied as separator or contactor can offer yet many more distinct advantages [1]. Two examples are membrane applications for more aggressive than aqueous feed streams or membranes where the barrier properties can be switched by external stimuli.

The majority of synthetic membranes are made from polymers because barrier and surface properties can be varied in wide ranges with help of established scalable manufacturing processes. Significant efforts have been made to further improve membrane performance by focussing on barrier properties (high selectivity, high flux) or surface properties (antifouling, affinity). In this presentation, we will discuss how the synthesis of novel membane polymers or the development of adapted polymer synthesis methods toward preparation of composite membranes can significantly improve the membrane performance or enable novel applications [2,3]. Here, important recent trends in the field will be illustrated with examples from own research.

In the first part, we will focus on the synthesis of polymers which can be used to obtain ultra- and nanofiltration membranes which can be used in organic solvents. In all cases, cross-linking of the polymer during membrane manufacturing is crucial, for adjusting the barrier properties or to obtain a solvent-stable membrane or both. Three different systems will be discussed, i) novel block copolymers from polyethyleneglycol and polyacrylonitrile for conventional phase separation and post-crosslinking, ii) modified commercial polyimides with photo-reactive groups for phase separation in combination with photo-crosslinking, and iii) tailoring of conditions to process commercial precursors for polyurethanes to obain thin-film composite membranes. The resulting novel membranes will also be compared with established materials.

In the second part, strategies toward stimuli-responsive membranes will be discussed with focus on materials where selectivity in the ultrafiltration range can be switched. Well-controlled grafting of a thermo-responsive polymer (cf. [4]) from the surface of ultrafiltration membrane pores can yield membranes where the size-selectivity can be tuned by the reaction conditions and the fractionation of nanoparticles can be reversibly switched by temperature. Reactive pore-filling with a hydrogel of tailored mesh size via in situ cross-linking polymerization is an alternative approach [5]. For another generation of such membranes, it will be possible to control the permeability and selectivity instead of heating the feed by “remote control”; this is possible by the integration of superparamagnetic nanoparticles in the membranes and excitation of the membrane by an external magnetic field.    

All these strategies have relevance to widen the scope of the membrane applications and to contribute to sustainable technologies.

[1]     E. Drioli, L. Giorno (Ed.), Membrane operations: Innovative separations and trans­formations, Wiley–VCH, Weinheim, 2009.

[2]     M. Ulbricht, Polymer 2006, 47, 2217.

[3]     Q. Yang, N. Adrus, F. Tomicki, M. Ulbricht, J. Mater. Chem. 2011, 21, 2783.

[4]     A. Friebe, M. Ulbricht, Macromolecules 2009, 42, 1838.

[5]     N. Adrus, M. Ulbricht, J. Mater. Chem. 2012, 22, 3088.