Breakthrough membrane research discusses pH controlled nanofilters

 

Breaking the boundaries of modern science by the means of innovative research is inherent to the interdisciplinary, academic fabric of King Abdullah University of Science and Technology. The highly specialized field of nanomaterials is no exception to this mindset, as a group of University researchers are exploring a new method of membrane film production.

Controlled drug delivery, sensors, and water purification all require films with an ultra-high porosity and monosized nanopores. Yet, common synthesized membranes used in nanofiltration are problematic because of their poor selectivity and broad pore distribution. The research team, led by Chemical and Life Science Engineering Professors Suzana Nunes and Klaus-Viktor Peinemann, are hopeful their research on pH-responsive nanoporous films will provide an alternative to this.

Their research paper, Switchable pH-Responsive Polymeric Membranes Prepared via Block Copolymer Micelle Assembly was highlighted in Nature Middle East and recently published in ACS Nano, a premier journal in the field of nanoscience and nanotechnology.

The research discusses a process to produce pH-responsive nanoporous films with uniform pore sizes. This uses phase inversion to combine the self-assembly of metal block copolymer complexes and conventional membrane production methodology.

The team behind the paper is based in the Advanced Membranes and Porous Materials Center and Water Desalination and Reuse Center. They have been investigating this process since September 2009 and were recently awarded $248,000 from the University Seed Fund to advance the research. The group includes Nunes, Peinemann, researcher Neelakanda Pradeer, and Postdoctoral Fellow Madhavan Kanurakaran. A patent for the membrane research was filed in January 2010.

All research was carried out at KAUST, except for some structural characterizations at the HASYLAB Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany.


Life science possibilities

"Earlier the goal for membrane research was to make the membranes faster and more selective, like with elements such as higher water flux or salt rejection. This is still the goal but now there is a demand for the production of more sophisticated membranes, like natural membranes that can react to certain elements," explains Peinemann.

The membrane will be used for life science applications. For example, in diabetes therapy pH-responsive pores can open or close to supply insulin according to the depletion of glucose and acid production.

The membranes are asymmetric. Their selective top layer is 100 to 400 nm thick and has an extremely high porosity. The pores are uniform and diameters can be tailored to between 5 and 20 nm.


Interdisciplinary institutional research

"It took us a long time to get to this stage," says Nunes. "It was difficult, as we had been researching these membranes before coming to KAUST. However once we came here our luck began to change.

"We used microscopy methods in the University's Core Labs that we did not have access to before. It was a challenge to get the image of the pores we wanted due to the high-level of characterization that combined everything in the field."

In an example of University's interdisciplinary approach to research, the team is currently working with faculty from the Mathematical and Computation Science and Engineering Division to develop polymers that are also responsive to other elements such as light and temperature. They are also collaborating with the University's Visualization Lab to create a 3D representation of the membrane and the process behind its creation.


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